# Caleffi pump issue



## Boardroom (Dec 27, 2014)

Hi Gang.
I took advantage of the mild weather we are having here and filled my 1000 gallon storage tanks.  The first burn on my new Econoburn EBW200 was today. I have to make sure I get the tanks heated up before it turns cold again
My first burn was only about half a load as I was a little nervous.  The  boiler only reached a156 degrees.  I initiated another burn soon after the first with a larger load of wood.  This time it got up to 163.  The tops of my storage tanks are at about 140,  but much less at the bottom.  I thought it would get hotter as I had the boiler target set at 170.  The wood I was using was seasoned two seasons and my manometer was reading perfect draft at .03.
I am suspecting that my problem is with my Caleffi 281 mixing/boiler protection valve.  Even when I had the boiler up to 160 and the input in the top of the valve was reading 160, the water going back to my boiler only ever reached 105. I have attached a poor picture but you get the idea.  I think the valve is suppose to recycle all water back to the  boiler until the return water reaches 140. Only then will it pump to storage.  In the picture my boiler is to the right and storage to the left.
I removed the small packing screw from inside the pump before I installed it so that is not the problem. If anyone else is using this pump can you tell me if I am missing something.
Boardroom.


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## leon (Dec 28, 2014)

I think you should plan on removing 
the valve and you will find dirt/scale in it
affecting the mixing valve and causing 
it to bypass.

DO you have unions where the valve is???? I hope so.


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## Boardroom (Dec 28, 2014)

Yes. Isolation valves all round so removing it is not a problem.  Should this be an issue when it is brand new though?


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## maple1 (Dec 28, 2014)

Are you sure the pump is actually pumping? If not, and if the caleffi is anything like the lk810, it is designed to convect fully to storage and bypass the thermostat until the pump kicks in - for overheat protection in a power outage situation.


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## Boardroom (Dec 28, 2014)

Pretty sure it is pumping. I can hear the motor and the rotor is turning according to my little magnet tool that you hold on the end of it.


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## Boardroom (Dec 28, 2014)

Should the rotor turn clockwise or counterclockwise?  Is it possible to wire it backwards?


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## maple1 (Dec 28, 2014)

Shouldn't be. I paralleled an indicator light with mine so I know when juice is being sent to it. Can you find power at the pump connections with a meter? If pump is indeed running might be some dirt in the stat. Might try lowering your pump launch temp & see what happens, say to maybe 150 or so, before taking things apart.


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## Boardroom (Dec 28, 2014)

I think there is definitely power to the pump as I have it wired with an on/off switch and I can hear it come on when I flip the switch. I don't have a meter.
Sorry Maple but I don't understand what you mean when you say to lower the pump launch temperature.  The Caleffi comes with insertable thermostatic sensor cartridges. Mine is set for 140 and is not adjustable. The 140 refers to the mixed temperature lower limit back to the boiler.


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## Boardroom (Dec 28, 2014)

Boardroom said:


> I think there is definitely power to the pump as I have it wired with an on/off switch and I can hear it come on when I flip the switch. I don't have a meter.
> Sorry Maple but I don't understand what you mean when you say to lower the pump launch temperature.  The Caleffi comes with insertable thermostatic sensor cartridges. Mine is set for 140 and is not adjustable. The 140 refers to the mixed temperature lower limit back to the boiler.



I should add that the pump is set up to run continuously unless I turn off the switch.


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## maple1 (Dec 28, 2014)

Boardroom said:


> I think there is definitely power to the pump as I have it wired with an on/off switch and I can hear it come on when I flip the switch. I don't have a meter.
> Sorry Maple but I don't understand what you mean when you say to lower the pump launch temperature.  The Caleffi comes with insertable thermostatic sensor cartridges. Mine is set for 140 and is not adjustable. The 140 refers to the mixed temperature lower limit back to the boiler.



I thought the 170 you referred to above was what you had your circ set to start at - 'launch temp'. So it might not get that high to start your circ pump. So lowering it would make your pump start earlier therefore use the thermostat. I have no experience with either caleffi or econoburn so might be speaking over my head here.


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## Bob Rohr (Dec 28, 2014)

try moving the gauges, they just pull out of the block.  It could be a bad gauge.  

What temperature sensor do you have?  The bypass line will be 100% shut down when you reach the sensor temperature plus 18.  So if you have a 130 sensor + 18 = 148 for complete shut down.

It will allow some flow to the system as the boiler heats up.

A large slotted bolt in the motor can be removed to see if the shaft is spinning, carefully as hot water may spray out.

Also if it was dropped sometimes the ceramic shaft can break, so the shaft my be spinning, when you remove that screw. but the impeller not. 

Two allan head cap screws remove the motor from the housing, run it with the motor out to see if the impeller spins.

Isolate all the valve before you remove, of course.


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## Boardroom (Dec 28, 2014)

Thanks Bob. I have already removed the unit from the system so I will check the shaft after lunch.   I think my sensor is 140.


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## Boardroom (Dec 28, 2014)

Boardroom said:


> Thanks Bob. I have already removed the unit from the system so I will check the shaft after lunch.   I think my sensor is 140.


OK Bob. I took the large slotted bolt out of the end of the motor and could see the shaft spinning.
I then removed the motor and turned the power back on. I could see nothing moving.  Is the impeller the big white thing with the black stripes in the middle?


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## Boardroom (Dec 28, 2014)

Boardroom said:


> OK Bob. I took the large slotted bolt out of the end of the motor and could see the shaft spinning.
> I then removed the motor and turned the power back on. I could see nothing moving.  Is the impeller the big white thing with the black stripes in the middle?


Sorry Bob. That was silly. The silver part stayed in the valve when  I took the motor off.  I pulled the silver shaft out of the valve can now see the impeller. When I turn the power on both of the shaft and the impeller spin.


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## Bob Rohr (Dec 28, 2014)

pumps okay, reassemble, move the gauges around, fire and let run a few hours.  it sounds like it should be fine.


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## Boardroom (Dec 28, 2014)

Bob Rohr said:


> pumps okay, reassemble, move the gauges around, fire and let run a few hours.  it sounds like it should be fine.


I put it all back together and lit the fire, moved the gauges around and got the same result no matter where the gauges were.  The top gauge was reading 160 and the right hand gauge (back to boiler) was only 105.  The left side gauge (from storage) was about 90.   It took about 1.5 hours to get up to 160.


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## Bob Rohr (Dec 28, 2014)

It takes some time to get thousands of gallons up to 180F.  The cooler water at start up heats quickly due to the large delta T.  as the tanks warm it a slower heat transfer into the tank.  If the boiler is running 160 supply, and in fact 90 is the return temperature from the load, then the valve will be bypassing quite a bit.

The gauges are all inserted into the brass body, not into the fluid, so there may be a little error.  If you are sure it is circulation, keep running.

Did you remove the shipping lock screw as shown in the installation manual?


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## Boardroom (Dec 28, 2014)

Thank you for all your help with this Bob.
Correct me if I am wrong but I thought that the valve functioned so that as long as the input from the boiler (top port) was less than 140 (my sensor) then all of the flow will be put back into the boiler so that the output port (bottom right in my case) and the top port will be close to the same temperature. If my bypass line into the top of the valve goes to 160, the outlet port to the boiler would still read 140 due to the mixing with the cold from the storage.
In my mind, it should make no difference what temperature my storage is at. If storage is cold the bypass will take care to send the hot water back to the boiler. What am I missing?
The packing screw was removed before the initial install.


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## maple1 (Dec 29, 2014)

That's how my LK810 works. 810 output to boiler return goes right to 140 as soon as the pump turns on - doesn't matter how cold storage is. Well, actually it goes to about 150 right at first then creeps back to 140.

EDIT: I'll add for what it's worth that it sounds like yours is acting like mine does at start up before the pump kicks on. The convection flow will return cold water from storage through the mixing valve to the boiler - until the pump kicks in, that is.


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## Boardroom (Dec 29, 2014)

My pump actually pumps continuously and the Caleffi valve just diverts the water to where it is suppose to go.  If the  return water is less than 140, the valve is bypassing storage.   Once return temps of 140 are reached it starts diverting to storage.
It seems like mine is bypassing OK until it gets to 140 but once it starts mixing It drops the return temps down to 105.  I wonder if something is wrong with the sensor in my valve.
My concern is that at 105 I am getting no boiler protection.


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## maple1 (Dec 29, 2014)

Your pump isn't controlled by boiler temps? Is that just a temporary arrangement?

Have you been burning steady? Or just once in a while? Wondering what would happen if you don't start the pump until the boiler gets hotter up top - like 180. It seems a bit tricky to not have the boiler temps play a part in controlling the pump starts & stops. But again not familiar with an EB at all.


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## velvetfoot (Dec 29, 2014)

This is just from memory, but I recall on my more basic Caleffi Thermomix 280 (I think) it could be hooked to for either supply or return temperature control.  Could you possibly have it piped up so it's controlling supply and not return temperature?  Just a thought.


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## Boardroom (Dec 29, 2014)

It is pretty clear on the valve which way everything is suppose to point so I think I have it plumbed properly. Here is the setup.


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## Bob Rohr (Dec 29, 2014)

Boardroom said:


> It is pretty clear on the valve which way everything is suppose to point so I think I have it plumbed properly. Here is the setup.
> View attachment 148833


here is a look at mine as it is running after start up.  I installed a pilot light to show when it is powered.

I also wired it to the EKO pump output, so it doesn't fire until the boiler is up to temperature.

It can be running and bypassing and still showing 105 on that return when it is just ready to close bypass.  In my example the EKO pump sensor just hit 140, so the pump is powered, it takes a few minutes for the temperatures to stabilize.  

Mine has been running for over 1 year now, i did change to a lower temperature sensor as the boiler would sometimes reach 170, and the fan started raving down before the bypass was completely shut.

I used the 115 sensor add the 18 differential for a 133F control temperature, works fine with dry wood, no creosote build up.


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## Boardroom (Dec 29, 2014)

So there is no flow through your boiler until boiler water temp reaches 140? Perhaps I should try turning my pump off manually until I get up to that also, then turn it on. Right now it is taking almost an hour to reach 140 with lots of smoke out the chimney.  That leaves me with a very short burn period at peak temperature.
My Econoburn manual states I should have minimum 140 back to the boiler for boiler protection. Mine stays at the 105 for the whole burn. My max temp reached so far on the boiler is 164.  With the bypass not shutting until 158 it doesn't leave much room.  You are saying that I can get away with less than 140 back to the boiler or is that just specific to the EKO?
Here is where I am confused.  If my sensor is 140, should my return temps not stay above that once the top port has reached 140+? I don't understand why it is 105.  Seems like I just keep pushing cold water back into my boiler.
Sorry for all the questions but I am new at this. Here is how mine looks after burning for almost 2.5 hours.


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## maple1 (Dec 29, 2014)

Have you verified those temps with something else?

Maybe a thermometer with a probe sensor that you could periodically move around from place to place (temporarily surface mount the probe to a pipe under some insulation), or an IR temp gun? Although my IR gun is kinda suspect.

You should try to maintain 140 entering the bottom of the boiler, yes. Quite important for long boiler life. But I am still wondering about your manually controlled or constantly running circ pump. It should start when the boiler gets hot, and stop when it cools off. By itself.


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## Boardroom (Dec 29, 2014)

I think my IR gun is suspect too.  I will try a temp probe on my next burn to see if I can confirm the temps.
I understand what you mean about getting the boiler temp up before the pump comes on.  I may have to consider rewiring it.


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## velvetfoot (Dec 29, 2014)

Tor the IR gun, it's best if the surface is black


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## Floydian (Dec 29, 2014)

Hello Boardroom,

I was really starting to think you had a bad thermostatic element BUT......

In the last pic you posted it sure looks like you are mixing 105 from the bottom of storage with 155 from the bypass and you are returning 120 to the boiler. IF, big IF here, you are pumping 10 gpm with a 35T through the boiler, then your boiler is putting out 175,000 BTUH. A good number for the ebw200, I think.

Now as far as the temp gauges, I have found with my LK810 Loading Unit that my mix temp usually shows 130 with "cold" storage. (low 90's or upper 80's ) I was concerned this was too low as I also have a 140 element. First I moved my temp gauges around-nothing. So I did as maple suggests here:



maple1 said:


> Maybe a thermometer with a probe sensor that you could periodically move around from place to place (temporarily surface mount the probe to a pipe under some insulation),



and I found that the LU temp gauges definitely read at least 5 lower than a sensor taped(and insulated) onto the 1.25"x6" sch. 40 pipe between my LU and my boiler. I believe if I could measure the actual fluid temp I would be very close to 140. I think with the way the temp gauges slide into the brass housing, you just can't get a very accurate reading. 10 too low would surprise me.

Noah


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## maple1 (Dec 29, 2014)

And on that note - I have no idea what my loading unit temp guages read. The way it's mounted, I would need to go around to the back of my boiler, get down on my hands & knees, and stick my head in a tight spot (after finding a flashlight). Don't think I've ever done that - I instead T'd in two tridicator guages on my boiler inlet & outlets & those are what I'm reading on anything temp related on my boiler ins & outs. They face me front & centre when I'm standing at the front of my boiler.

Hmm, I should actually check out my loading unit guages for once - got me curious now. Will try to remember later tonight when I'm burning...


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## Boardroom (Dec 29, 2014)

Thank you for all the replies lads. I am starting to get things worked out.
I have some digital temp gauges so I mounted the small probes on the pipes coming to and from my loading unit.  The input gauge on my valve was reading properly, at about 165 degrees.  The mixed return back to the boiler was reading about 120 on the gauge but my probe says it was 143.  If I believe the probe, which I think I do, all is well with the mixing valve.   I feel a lot better now knowing that I have the proper boiler protection.
Also Maple, I think you are onto something with not starting my pump until the boiler heats.  I tried it with my burn this afternoon.  No pump until the boiler hit 150, then I started it with my manual switch. It only took about 35 minutes to get to 150 with smoke disappearing at the chimney even earlier.  Previously it would take me about 1 1/4 hours, and enough smoke to choke a small village, to reach the same temp.  I expected that the temp in the boiler would drop when I turned the pump on but it didn't. It just kept rising.  Also, I was able to achieve my highest boiler output of 167. My boiler coasted at this point as I was nearing my target setting of 170.
Floydian man, you are confusing me with all that delta stuff. All I know is that I have the Caleffi valve on medium speed, 1 1/4 inch piping to and from the boiler. Here is the pump chart that I have no idea how to read.


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## Bob Rohr (Dec 29, 2014)

Boardroom said:


> Thank you for all the replies lads. I am starting to get things worked out.
> I have some digital temp gauges so I mounted the small probes on the pipes coming to and from my loading unit.  The input gauge on my valve was reading properly, at about 165 degrees.  The mixed return back to the boiler was reading about 120 on the gauge but my probe says it was 143.  If I believe the probe, which I think I do, all is well with the mixing valve.   I feel a lot better now knowing that I have the proper boiler protection.
> Also Maple, I think you are onto something with not starting my pump until the boiler heats.  I tried it with my burn this afternoon.  No pump until the boiler hit 150, then I started it with my manual switch. It only took about 35 minutes to get to 150 with smoke disappearing at the chimney even earlier.  Previously it would take me about 1 1/4 hours, and enough smoke to choke a small village, to reach the same temp.  I expected that the temp in the boiler would drop when I turned the pump on but it didn't. It just kept rising.  Also, I was able to achieve my highest boiler output of 167. My boiler coasted at this point as I was nearing my target setting of 170.
> Floydian man, you are confusing me with all that delta stuff. All I know is that I have the Caleffi valve on medium speed, 1 1/4 inch piping to and from the boiler. Here is the pump chart that I have no idea how to read.
> View attachment 148881




Sounds like it is working, and I do agree turning on the 281 with the EKO pump connection, or any temperature control is much preferred.

Remember all 3 temperature gauges are drilled into that brass housing.  Possibly that is mis-leading as more accurate temperature would be downstream from the component with the probe into a well in the fluid stream, or a well insulated strap on temperature sensor downstream.  

The 3 gauges seemed like a good idea for owners to check, but not if the accuracy is that far off, sorry.
Let me know how it works out.


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## Boardroom (Dec 29, 2014)

No need to apologize Bob.  The valve works exactly as advertised. As for the gauges, now that I know the temp difference, they are still a good reference.
We can always use someone with your knowledge on the forum.
Thanks again.


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## maple1 (Dec 30, 2014)

I did check my dials on my pump unit last night. My tridicator guages were showing 165 out & 145 in at the boiler fittings, while the outlet guage on the unit was 140 (5 degree diff) and the bypass guage was 150 (a 15 degree diff). So ya I guess they aren't super accurate.

You should get your pump control sorted. No idea what the EB has on-board for that - but I would think it would have something. I think starting it at 150 is even too low, I would try starting it at 170. You could have a lot of excitement if you forget to start it just once - and also could waste storage if you don't turn it off early enough at end of burn.

Good to hear of progress though.


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## Clarkbug (Dec 30, 2014)

I agree, you should interlock the pump control with the boiler.  

You shouldnt be having any real smoke if you are gasifying, so its important to get the boiler up to temp then start the pump.


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## Boardroom (Jan 3, 2015)

I have been experimenting with this process and it definitely works better with heating the boiler  before turning the pump on. I guess I was under the misconception that pumping around the small boiler loop was basically the same thing.  Heat the small loop (small volume) along with the boiler before Caleffi valve diverts flow to storage.
Have a look below at how my connections from boiler to storage are connected.  Initially I was leaving the pump off while I heated the boiler. However, this still seemed to be taking too long to get to temp.  Then I realized that my Caleffi valve has a failsafe in it that allows thermosiphon flow through the pump if there is a power failure.  If I turn the pump off (imitating a power failure), I am initiating the thermosiphon process which is drawing cold water directly from the bottom of my tanks through the boiler.  This is worse than leaving the pump on and having mixed water return to the boiler.
My solution is to close the ball valve coming from storage (the red one in the picture) until the boiler heats up.  This seems to solve the problem except that I have to reopen it manually before I turn the pump on.  Even if I wire the pump up so that start and stop are controlled by the boiler, it won't work if I have to open the valve manually.
Anyone see a better way?


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## maple1 (Jan 3, 2015)

Yes - that can be a real catch-22 with good convection flow between the boiler & storage when using a loading unit. Such convection flow is usually a good thing. Mine isn't that good, but I still have a period of time between lighting the fire, and when the pump kicks on, during which I have cold water entering my boiler. But even with cold storage (say 120), it usually is only 20 minutes or so before my pump kicks on.

Short term, I see maybe doing something like you're doing - except I don't think I'd close the valve but maybe only partly close or throttle it. Which is kind of a pain though because you're then tending the valve with each burn - and usually manual valve operation is poor practice. The other thing would be to burn before bottom of storage gets too cold. How cold is your storage when you do a burn? Might have to find a balance between that, and when you start your pump. When are you starting your pump? 20 minutes or so after lighting seems to be right here, time-wise. Usually my boiler is hitting the 170-180 range at the top by then. Starting at 160 at boiler top might be a decent thing to shoot for, considering 140 return to boiler and generally accepted 20° delta-T through the boiler.

My boiler also uses a flue gas thermostat during normal start up. When it gets up to temp, it starts the pump. But it's also paralleled through an aquastat, so if the boiler gets too hot before the flue gas sees temp, the aquastat will take over & start it. The flue gas stat stops the pump at end of burn. No idea what the EB uses - but you could also maybe check out getting & using one of those? Mine came with my boiler but should be available separate though a dealer.


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## Boardroom (Jan 3, 2015)

I turn my pump on when the boiler reaches 170. I should probably do a better job of heating my tanks all the way to the bottom as they are generally around 110 even when I heat the top to 175.  If my boiler is reading 85 when I get up in the morning it takes me about 30 minutes to get to 170.
The end of my burn also creates the same issue.  If I turn the pump off when the boiler cools, in order to avoid pushing cool water into storage, the valve again starts to thermosiphon cold water through the boiler and into storage unless I close the red valve mentioned above.


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## Deering (Jan 3, 2015)

I had a similar problem with my Caleffi circulator.  Return water to boiler was lower then the 130F the valve was set at.  I finally installed two therm wells, one upstream and the other downstream of the pump on the return line.  Mystery solved.  The Caleffi thermometers were totally uncalibrated.  The Caleffi is working perfectly - boiler always gets 130 regardless of the incoming temp.  So I don't even use them now but rather rely on the thermos that are directly in the flow.  But there is a small screw head at the end of the Caleffi thermo probe end for calibration - I didn't bother.

Happy I solved it.  I was suspecting a faulty cartridge.  Good luck finding one.  Every supply place I contacted had a hard time even locating a part number.  Sounds like they had to order it direct from Italy.  Crack your wallet and bend over.   

One other note:  The pump curve chart accompanying my Caleffi shows the three curves for the three pump settings...it's wrong.  The curve labeled #1 actually corresponds to pump setting #3 and vice versa.  Maybe they switched the pump labels at some point and forget to update the curve chart...whatever the case - sloppy.  You might check yours as well - perhaps it's been updated.  You'll be able to hear the pump change speeds when you switch the settings.


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## Bob Rohr (Jan 3, 2015)

Deering said:


> I had a similar problem with my Caleffi circulator.  Return water to boiler was lower then the 130F the valve was set at.  I finally installed two therm wells, one upstream and the other downstream of the pump on the return line.  Mystery solved.  The Caleffi thermometers were totally uncalibrated.  The Caleffi is working perfectly - boiler always gets 130 regardless of the incoming temp.  So I don't even use them now but rather rely on the thermos that are directly in the flow.  But there is a small screw head at the end of the Caleffi thermo probe end for calibration - I didn't bother.
> 
> Happy I solved it.  I was suspecting a faulty cartridge.  Good luck finding one.  Every supply place I contacted had a hard time even locating a part number.  Sounds like they had to order it direct from Italy.  Crack your wallet and bend over.
> 
> One other note:  The pump curve chart accompanying my Caleffi shows the three curves for the three pump settings...it's wrong.  The curve labeled #1 actually corresponds to pump setting #3 and vice versa.  Maybe they switched the pump labels at some point and forget to update the curve chart...whatever the case - sloppy.  You might check yours as well - perhaps it's been updated.  You'll be able to hear the pump change speeds when you switch the settings.




Got a pic of the switch on your pump?  Speed 1 has always been the low speed on any circ I have worked with?  Possibly the label on the Wilo is incorrect.

Either way we need to get it right, thanks for catching that.


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## Deering (Jan 3, 2015)

I stand corrected, Bob.  Switch one does correspond to the low curve.

My pump is oriented so I can't see the switch due to piping and my boiler preventing my fat punkin from getting back there.    Ended up laying on my belly like a reptile and reading it with a mirror.  After a half hour of twisting my neck and squinting and swearing, I was pretty sure I was reading the numbers right.   

Tried photographing it with my iphone but it couldn't macro-focus that tight.  But last week I cleaned up my phone sparkly clean and now it works a lot better.  The cleaning process involved leaving it in my pants pocket and throwing the pants in the wash machine.  The new version of the iphone has a better camera...

So I just went and photographed it again per your request, and lo and behold the numbers match the curve!  The paint coating over the number stamp is pretty thick which makes it impossible to distinguish from an angle.

Ignore what I said about the pump curves in my previous post...


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## Boardroom (Jan 3, 2015)

My valve is labeled correctly. 1 low, 3 high.  I found the same thing as you Deering. The pump works just like it is suppose to, although the temp dials take a little negotiation.
If you and Bob are using the same pump, can I ask you to describe how you use it? Run continuously or start when boiler reaches temp?  I think you said you start yours at temp Bob.  How do you handle thermosiphon through the valve if you turn it off after the burn?


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## maple1 (Jan 3, 2015)

I'm thinking there shouldn't really be that much thermosiphon at end of burn. What drives that is heating of water, and once the fire is out that ends that. The lighter hotter water will want to rise to the top, and as long as the top is top of storage, and hotter water isn't being generated in the boiler, there shouldn't be movement.


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## Deering (Jan 3, 2015)

Mine runs when the boiler is running.  My pellet boiler controls the pump, so when it shuts off, the pump shuts off.  I've inserted a bit of time delay so the pump runs for an additional 10 minutes after the boiler shuts off, in an attempt to suck the last little bit of heat out of it.  At startup the boiler delays starting the pump until it reaches 130 degrees.

The pump has a built in flapper valve that prevents siphoning short-circuiting through the pump.  It lets the boiler to siphon naturally through the storage tank, but I think that will achieve equilibrium as long as the boiler and tank are at the same level.  If one or the other were on a different level, then you'd need to add a check valve between the boiler and the tank.


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## Boardroom (Jan 3, 2015)

My boiler is usually hotter than the bottom of storage when I shut it down so I think I still get the thermosiphoning, no?  As you know I have just starting learning this burning process last week when I lit my boiler for the first time. I have burned wood stoves for 30 years but this is a whole new game.  Should I leave the boiler and pump on as long as the boiler is hotter than the bottom of storage or turn it off if it is less than the top of storage.
Deering, you can see from my avatar that the top of my tanks is quite a bit higher than my boiler. On Maple's suggestion some time ago, I moved my supply pipes to the top of the tanks. From what you can see, Is my biggest thermosiphon concern going to be from the bottom of the tanks through the boiler or from the top of the tanks circulating back down to the bottom?  I ask because I can always add a check valve in the top line to prevent flow back out the top of storage when the pump is off but I cannot add one anywhere on the bottom.


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## maple1 (Jan 3, 2015)

If your boiler isn't hotter than top of storage I don't think you'll get much thermosiphoning. And if bottom of storage is colder than the boiler, that cold water will want to stay where it is, at the lowest point. Unless it is being pushed out by water coming in the top.


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## Bob Rohr (Jan 3, 2015)

Deering said:


> I stand corrected, Bob.  Switch one does correspond to the low curve.
> 
> My pump is oriented so I can't see the switch due to piping and my boiler preventing my fat punkin from getting back there.    Ended up laying on my belly like a reptile and reading it with a mirror.  After a half hour of twisting my neck and squinting and swearing, I was pretty sure I was reading the numbers right.
> 
> ...




Thanks for checking, I'll sleep better without wondering.


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## heaterman (Jan 3, 2015)

*Tried photographing it with my iphone but it couldn't macro-focus that tight. But last week I cleaned up my phone sparkly clean and now it works a lot better. The cleaning process involved leaving it in my pants pocket and throwing the pants in the wash machine. The new version of the iphone has a better camera..*

Like,   Can't begin to tell you how many gadgets I've gotten to work better using the same method. Glad I'm not the only one..  lol

PS......gauges. don't even get me started. The 4" square Weiss we installed on the main piping of a recent project reads 20-25* low. AAAAARRGGH 
That's a $65.00 gauge  AAAA AAAAAAARGH !


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## Deering (Jan 3, 2015)

Boardroom said:


> From what you can see, Is my biggest thermosiphon concern going to be from the bottom of the tanks through the boiler or from the top of the tanks circulating back down to the bottom?



Those are fair questions, Boardroom.  And I'm not entirely sure about the answers.

As maple says, the hot water in the tank isn't going to want to flow downhill.  And the cold water in the bottom of the tank won't run uphill.  So no problem, right?  Maybe not.

Here's the dynamic I see that could change things.  Your storage tanks are much better insulated than your boiler, if for no other reason than because your boiler has a big flue pipe running through it.  So your boiler will cool off faster than your tanks.  Assuming everything is idle, no circulators running, the boiler will soon be colder than the bottom of your tank.  So the boiler water will want to run downhill into the tank.  But water doesn't compress, so the displaced tank water has to go somewhere, and that's from the top of the tank down into your boiler.  

This can only occur if the downward forces of the denser cold boiler water is greater than the buoyant forces of the hot tank water.  At some point the temperature differential may make that possible.  It also depends on the relative heights of the tank and boiler.  All of this requires math that is beyond me on a Saturday night (or any other time since I graduated college 100 years ago...).

A simpler solution is to add a swing (not spring controlled!) check valve in upper line that will prevent reverse flow from the tank to the boiler.  You want to make sure the boiler can freely release hot water through the check to the tank to prevent trapping combustion heat in the event of a power outage shutting off circulation.


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## Bob Rohr (Jan 3, 2015)

Boardroom said:


> My valve is labeled correctly. 1 low, 3 high.  I found the same thing as you Deering. The pump works just like it is suppose to, although the temp dials take a little negotiation.
> If you and Bob are using the same pump, can I ask you to describe how you use it? Run continuously or start when boiler reaches temp?  I think you said you start yours at temp Bob.  How do you handle thermosiphon through the valve if you turn it off after the burn?




Every system behaves differently, just try and see, but I doubt thermosiphoning will be an issue.

You could lock the "gravity gate" check valve closed with the shipping screw that came with it, not every application wants, or needs thermosiphon feature as an over-heat safety option. As long as you have some other over-heat mechanism.

Mine is controlled by a differential controller (solar control)  on when the boiler is 10° warmer than the tank, but a min. 140.  off when it is within 5° of the tank.  I also ran it with the EKO pump output, the solar controller gives me more adjustability and also has a second function for buffer to system on/ off.


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## Boardroom (Jan 4, 2015)

Thanks Deering. I understand what you are saying and I considered putting a check valve there as shown in a page from the Caleffi Manual attached. Check out the last sentence on the left hand side of the page. I didn't do it because I didn't want to add resistance to that line as the thermosiphoning valve is my only overheat savior. Less resistance means more siphoning. Anyone know if this would actually create enough resistance to worry about?


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## DaveBP (Jan 4, 2015)

It might be useful to think of the thermosiphon potential as being driven by gravity, not the buoyancy of hot water. Gravity PULLS cooler, denser water DOWN. It does not PUSH warmer, less dense water UP. 

  If the bottom of the storage tank is level or above the bottom of the boiler:  the cooler, denser water in the tank might be able settle down into the boiler after the burn is producing water hotter than the top of the storage tank. This might be able to push water from the boiler to the top of the tank even if the top of the tank is warmer than the water coming from the boiler. Depends on the differences in the temperatures (and a busload of other variables). 

You would never expect this by using the warm-water-rises perspective. So looking at your system with gravity as the driver (and gravity only pulls down) might let you analyze some puzzling behavior that would otherwise remain a mystery.


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## Deering (Jan 4, 2015)

Boardroom said:


> Anyone know if this would actually create enough resistance to worry about?



Your attachment didn't attach, so I can't see your exact reference.  According to the class I took from John Siegenthaler, the guru of biomass hydronics, a horizontal swing check is the right solution for this application.  A swing check only closes by gravity, so it takes very little pressure to lift it open.  Think of an unlatched door - hardly takes any force to push it open from one direction, but just about impossible from the other.  

Swing checks (for this type of application) are simple, inexpensive, and low-maintenance.  Sized properly, they have low pressure drop in the system.  Make sure to install them horizontally so gravity will close them.

And in a worst case scenario, you still have the boiler's pressure relief valve.


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## Deering (Jan 4, 2015)

DaveBP said:


> If the bottom of the storage tank is level or above the bottom of the boiler: the cooler, denser water in the tank might be able settle down into the boiler after the burn is producing water hotter than the top of the storage tank.



DaveBP has it right here.  But what he's describing isn't a problem.  You would want that type of thermo-siphoning since it would be extracting more energy from your boiler.  It's later where the issue begins.

The boiler will cool faster than the tank because the boiler loses heat faster than the tank.  Think of the boiler as being a radiator in this case (an inefficient one, but a radiator nonetheless relative to the well-insulated tank).  At some point the water near the top of the boiler will be colder than the water at the equivalent height in the tank.  So the boiler water will be more dense (heavier) than the tank water.  It wants to sink until it reaches the same level as equivalent temp water in the tank.  But the tank water has a column of warmer water above it pushing down, so it doesn't want to be pushed upward.  

Once the water in the boiler cools enough, it will become dense enough that it can overcome the downward force of the tank column, and it will push into the tank, causing the warm water at the top of the tank to be forced into the boiler, where it will cool down and become denser, and the cycle continues.  As DaveBP says, there are a lot of variables in play, and water is a fluid, not a solid object, so the dynamics become complex very quickly.  If the boiler were higher than the tank, the problem would become a lot more acute.  

Basically, it's this thermo-siphoning that you want to eliminate, allowing the boiler to become a radiator sucking heat out of your system.  A check valve preventing hot water in your tank from flowing back into your boiler prevents that.  I doubt that the issue would be very severe in your setup with your tanks being so much taller than your boiler.  The only way to tell would be to have enough thermometers in the system to be able to monitor tank upper and lower temps along with your boiler temps.  If the temperature at the top of the idle boiler consistently is close to the temp at the top of the idle tank over a long period of time, then you probably have some siphoning going on.


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## DaveBP (Jan 4, 2015)

That's the primary purpose of that flapper valve in the loading units; to prevent  backward flow from the top of storage toward the boiler. I would think that if one's system uses a loading unit rather than the simpler (and vastly cheaper!) thermostatic valve/bypass loop method then another check valve might be superfluous.


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## Boardroom (Jan 4, 2015)

Sorry. Here is the missing attachment.
The flapper in the valve prevents flow back through the valve from the bottom of the boiler so the check valve as in the attachment would be redundant if that is the objective. But, can the flow, without the check valve in place, siphon down the bypass loop into the top of the valve and then back through to the tanks or the other way up through the boiler?  The bottom of my boiler is a few inches lower than the bottom of my tanks so using BP's theory of gravity, the cool water in the bottom of my boiler would prevent this from happening?


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## Clarkbug (Jan 4, 2015)

Boardroom said:


> I turn my pump on when the boiler reaches 170. I should probably do a better job of heating my tanks all the way to the bottom as they are generally around 110 even when I heat the top to 175.  If my boiler is reading 85 when I get up in the morning it takes me about 30 minutes to get to 170.
> The end of my burn also creates the same issue.  If I turn the pump off when the boiler cools, in order to avoid pushing cool water into storage, the valve again starts to thermosiphon cold water through the boiler and into storage unless I close the red valve mentioned above.



Are you burning every day?  I only ask because my setup never gets that cold at the bottom unless I haven't burned for several days.  

Your thermosyphon shouldnt be able to pull heat out of your boiler that quickly once you are at full fire.  Have you gotten all of your storage up to full temp at this point?  Or are you still warming things up?  

Sorry for all the questions, but it seems like something strange is going on, not just with the loading valve.  Is your bypass damper closing fully?  Are you using any kindling when you build a fire?  

Since thermosyphon is the only overheat protection you have, I would definitely not use that valve at all.  Too much of Mr. Murphy possible.

Your initial thought about the operation of the loading valve and heating a small volume is correct, but I'm not sure if the controls on the econoburn are set to integrate with it.  What is the volume of water that your boiler can hold?


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## DaveBP (Jan 4, 2015)

I don't see why the hot water at the top of the tank would be driven toward the bottom of the same tank without a circulator running.
Perhaps a miniscule flow if the pipes and fitting were uninsulated and as the water in those pipes cooled to a lower temperature than all the rest of the plumbing.

In an unheated basement or similar place this might add up to something noticeable.


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## Deering (Jan 4, 2015)

Boardroom said:


> The flapper in the valve prevents flow back through the valve from the bottom of the boiler so the check valve as in the attachment would be redundant if that is the objective.



I'm not sure how effective that flapper valve is against backflow.  It appears that its primary purpose is to shut off the unconstrained flow of cold water from the tank to the boiler during pump operation, forcing it to pass through the loading valve instead.  If it's effective, then there's probably no need for another check, but at the low flow-rates that this siphoning produces, I'm not convinced that the flapper yields an adequate seal.




Boardroom said:


> an the flow, without the check valve in place, siphon down the bypass loop into the top of the valve and then back through to the tanks or the other way up through the boiler?



A siphon within the boiler side of the system could be set up, flowing through the circulator and loading valve back to the bottom of the boiler.  But if the pipe runs are short (as in your case) and insulated, it will be pretty insignificant.  Besides, you're more worried about siphoning your tanks than the idle boiler.  If the loading valve in the Caleffi is below the set temp (130 or 140), then the loading valve will be closed and there won't be a direct siphon path, except possibly through the flapper valve if it doesn't seal.  Again, with your setup that doesn't seem likely.




Boardroom said:


> The bottom of my boiler is a few inches lower than the bottom of my tanks so using BP's theory of gravity, the cool water in the bottom of my boiler would prevent this from happening?



Not really.  It's the relative heights between the top of your boiler and the top of the tank that will be the main factors in this.


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## Deering (Jan 4, 2015)

Clarkbug said:


> Since thermosyphon is the only overheat protection you have



I trust that there's also a pressure relief valve on the boiler.  If not, then you have bigger worries than siphoning.  That would be the first order of business to address immediately.  

But I think your concern is to provide a path for hot water to naturally siphon to the tank if, for instance, there was a power outage during fire and the circulator between the boiler and the tanks went down.  You'd still have fuel burning and producing heat.  Then you'd want to provide somewhere for that heat to go w/o relying on the pressure relief valve to pop.  I don't think a swing check is going to prevent that natural flow from occurring.  The swing flapper will open long before you build up enough pressure to trigger your relief valve.


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## DaveBP (Jan 4, 2015)

Referring back to your original post I have a few questions:

Since you say you just filled your storage tanks are you sure that some kind of crud didn't flush down into the loading unit as soon as it started circulating?
Is the water still in the bottom of your tank the original fill water? If so, what temperature is it now?
Did you try pulling the 3 thermometers out of that loading unit and holding them in a sauce pan full of boiling water to see if they all read about 212F (or 100C)?
Do you have the cast brass model? I've never been able see how those 3 thermometers in the same casting could separate the temperatures of the 2 or 3 different flows without effecting each other. To tell the truth, I've never even looked at mine. Have no idea what they show. Maybe next fire?


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## Clarkbug (Jan 4, 2015)

Deering said:


> I trust that there's also a pressure relief valve on the boiler.  If not, then you have bigger worries than siphoning.  That would be the first order of business to address immediately.
> 
> But I think your concern is to provide a path for hot water to naturally siphon to the tank if, for instance, there was a power outage during fire and the circulator between the boiler and the tanks went down.  You'd still have fuel burning and producing heat.  Then you'd want to provide somewhere for that heat to go w/o relying on the pressure relief valve to pop.  I don't think a swing check is going to prevent that natural flow from occurring.  The swing flapper will open long before you build up enough pressure to trigger your relief valve.



Agree, the swing check wont get in the way of the thermosyphon.  I was referring to the manual ball valve that he had referenced he could close to help increase the boiler temps.


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## Deering (Jan 4, 2015)

Clarkbug said:


> I was referring to the manual ball valve that he had referenced he could close to help increase the boiler temps.



Ah.  Got it.  Yeah, manually closing a valve between an active boiler and its load sounds like a bad recipe.  I can think of a number of distractions, both good and bad, that would cause me to forget to open that valve...  Better to control the circulator based on boiler temp.  That's not too difficult to set up.


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## Boardroom (Jan 5, 2015)

Good morning guys. Thanks for all the input. I didn't get a chance to reply as I was out to a hockey game last night.  That's what we do up here. I will try to address the questions that have come up.
1. There doesn't seem to be any crud in the valve. I took it all apart yesterday.  I refurbished a bunch of old CI rads for my install and there was lots of rust, dirt, discoloration in the system so I spent all day yesterday emptying it all and refilling it so I am off to a fresh start.
2. Yes. There is a pressure release valve on the boiler and another in the house on the electric boiler which runs on the same loop. Both are set at 30.
3. 42 gallons of water in my boiler.
4. Just so there is no confusion over how my valve works, I have attached a description.  My valve is the one on the second page.  The flow works the same as on page one. It is just that my protection valve and pump are all one unit. Econoburn controls are not set up to work in conjunction with it.  My plan was to run it continuously while the boiler is fired. Turn it on manually before I light the fire. Turn it off manually when I am done burning.  The valve takes care of all the flow so my understanding was that I did not need the boiler to control it.  The valve is wired separate from the boiler. The EB's pump controls are set up for a two pump system. One pump to run the boiler loop and another to run the primary loop to storage. Boiler loop terminals are energized at boiler temps less than 150.  At 150 the boiler loop shuts off and the primary pump terminals are energized. I suppose I could use the primary pump terminals to energize my pump instead of doing it manually. Would make it more convenient for sure but the only heat advantage is that I don't run the boiler loop until things are up to temp. Is that a concern given that the boiler loop is so short?
5.My tanks never really got a chance to warm on the bottom.  Today I am seeing if I can heat the storage all the way through.
6.My thermosiphon concern is when the pump is off. When it has no power it is designed to allow siphon from the bottom of the tanks up through the boiler. Come to think of it, I probably cannot allow the EB controls to start the pump because as the boiler is warming, flow will be moving through it if the pump is off.  I am probably better off with it running controlling the temp flow back to the boiler.
7. The check valve in the top line is probably a good idea but will need to wait until spring.
8. We have determined that the temp gauges on the valve are not all accurate.  They threw me for a loop initially but since then I have mounted sensors on the pipes to and from and the valve seems to be working fine. 
9. I will be a good boy and leave the manual valve open.


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## maple1 (Jan 5, 2015)

Since you have your Caleffi wired & switched completely separate - do you have anything at all hooked to your 'primary' & 'boiler loop' control pump contacts?

I googled up a manual for your boiler. I think I would wire the loading unit to the 'primary' control power - which according to the manual should turn the pump on at 150? Again, no EB experience here - but as far as I know every boiler should come with controls that turn a pump off & on at a given boiler temp, and that looks like it to me for the EB. With the Caleffi, you shouldn't need to use or worry about the 'near boiler' pump stuff. You could also add in a flue temp stat if you wanted to use flue temps to do it. You should also be able to utilize a flue gas stat to do end of burn fan & pump shut down.


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## Boardroom (Jan 5, 2015)

Nope. Both terminals are open.
The problem I see with having no power to the pump/valve until a certain temp, say 150, is that the valve will be allowing thermosiphon from the tanks up through the boiler.  Depending on bottom of tank temps it could take longer to heat the boiler this way than having the valve control the boiler loop return temps.


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## DaveBP (Jan 5, 2015)

I wouldn't look too closely at what your system is doing (as long as it's safe and heated water is going to your tank) until you have that last bit of original cold water through the boiler once. When you refer to "cold"  water return the difference between 10C and 35C is huge. And it will take a long time to get it up to that point. Until your return water temperature is closer to normal the loading unit won't act as you hoped. 

That was my experience with my loading unit and 1000 gal. tank.


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## ewdudley (Jan 5, 2015)

Boardroom said:


> Nope. Both terminals are open.
> The problem I see with having no power to the pump/valve until a certain temp, say 150, is that the valve will be allowing thermosiphon from the tanks up through the boiler.  Depending on bottom of tank temps it could take longer to heat the boiler this way than having the valve control the boiler loop return temps.


Exactly.  With a loading unit that has a backflow-preventer/fail-safe bypass valve the pump needs to run any time the boiler is 'active' regardless of 'launch temperature', up until end-of-burn shutdown.  Also IMHO there should be a mechanical aquastat on the boiler supply pipe that disables the draft fan and enables the boiler circulator whenever there is a supply over-temperature condition.


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## maple1 (Jan 5, 2015)

Have you started a burn with the pump not running and observed your boiler top temps to see how fast they rise? I am thinking your boiler should be able to generate way more heat than thermosiphon would be able to carry away, especially since the thermosiphon won't really get going until the boiler gets a decent temp gradient going - but I could be wrong on that. My boiler, due to the natural draft, is a bit slower to get the burn up to speed than those with fans (I think), and I still am able to get up to pump start temps in 20 minutes or less starting with a room temperature boiler. I think you will see a big improvement once you get storage throughly heated. Mine gets no cooler than 100 at the bottom in heating season - usually in the 120 range. Which is only 20 less than the magic 140 figure.


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## Boardroom (Jan 5, 2015)

Thanks EB - I do have an aquastat on the boiler supply line that shuts off the draft fan, I think at around 200. The pump is running continuously on a seperate circuit so no problem there.


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## Boardroom (Jan 5, 2015)

What I don't have is an overheat zone on a separate circulator. There are terminals on the EB that would energize when the supply line aquastat shows overheat. I just have not used them. As long as I have capacity in storage that should be able to absorb the extra heat.  What would be nice is to find a way to simply have my main pump notch up a speed when an overheat occurs.


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## Boardroom (Jan 5, 2015)

I hope to get storage charged up today so I'll let you know how it goes.


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## DaveBP (Jan 5, 2015)

My older forced-draft Tarm Solo has basic relay logic that turns on the circulator as soon as the system is reset to fire the next load after a normal shut-down. Basically, the circulator is always ON until after a burn when the exhaust gas goes below a temperature I've forgotten (but works to shut off the draft fan when the last coals are almost completely finished). This seems to me to be designed for use with a loading unit with that flapper valve.

With a tank still supplying well-temperature water through that thermosiphon opening it could take a long time indeed to get the boiler up to operating temperature if the circulator weren't running.


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## Deering (Jan 5, 2015)

Boardroom, do you have your tanks plumbed in parallel or series?  By series I mean the boiler goes into the top of one tank, and that tank's bottom connection goes to the top of the next, whose bottom goes back to the boiler.  I think a series configuration might be more resistant to siphoning, but I'll have to think about that a bit more.  In any event it will allow you to get more heat into the tanks when you do burn.


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## Clarkbug (Jan 6, 2015)

Boardroom said:


> I hope to get storage charged up today so I'll let you know how it goes.



I think this could make a big difference.  Startup is always a little funky for me, so please do let us know if having "warm" storage makes things handle a little more predictably.


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## maple1 (Jan 6, 2015)

Deering said:


> Boardroom, do you have your tanks plumbed in parallel or series?  By series I mean the boiler goes into the top of one tank, and that tank's bottom connection goes to the top of the next, whose bottom goes back to the boiler.  I think a series configuration might be more resistant to siphoning, but I'll have to think about that a bit more.  In any event it will allow you to get more heat into the tanks when you do burn.


 

avatar sez parallel...


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## Clarkbug (Jan 7, 2015)

Any updates OP?  Were you able to get the storage tanks charged up to see if it made a difference?


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