# Boiler piping schematic with pressurized storage



## tuolumne (Jan 24, 2008)

Here is my piping schematic.  I finally figured out how to draw something where I could easily get it online.  The circulator nearest the boiler will cycle water near the boiler until the danfoss opens at 140 degrees.  At that point water will circulate through the twin 500 gallon storage tanks.  If the house or DHW zones call, the primary loop circulator will start.  The 3 way mixing valve diverts return water above the setpoint back to the zones.  As a result, the reduced flow back to the boiler allows the boiler circulator to continue to charge the tanks with left over heat.  If the boiler is off, the primary circulator will draw water off of the storage tanks.  I just switched from a supply/return manifold scheme to the primary/secondary piping.  Please let me know if I am missing anything glaring.  Where do I need other items like checkvalves, isolation valves, drains etc.  Thanks.


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## Nofossil (Jan 24, 2008)

Nice looking schematic. What did you use to draw it?

The three way valve has cold inlet on bottom, hot inlet on right, and mix out on left?


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## tuolumne (Jan 24, 2008)

Thanks nofossil, I drew it in AutoCAD LT and used the publish to we option for printing a jpg.  Text is grainy.  I hope to use this valve to shed water above the setpoint back to the supply manifold.  I want two outlets and one inlet.  Is a three way mixing valve the wrong product?  I think what I want is a diverter valve.  What I have is a Tekmar 712.  Oops.


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## Nofossil (Jan 24, 2008)

I'm hoping someone with more plumbing experience than me will comment on this. My head hurts trying to figure out what happens to pressures at different points in the system with all of those pumps running in different combinations.  

To keep my head from exploding, I keep it simple by having only one pump running at any time. I'll have two when I have a radiant zone, but one will be contained within the zone just as you've drawn.

Looks like you have flow in one direction for heating the tanks, and in the other for drawing from them. I think that's the way to go. You'd want to plumb them to promote maximum thermal stratification.


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## solarguy (Jan 24, 2008)

I'd pipe the 2- 500 gallons in a reverse return configuration. This would ensure equal flow
& equal heat distribution thru both tanks.


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## tuolumne (Jan 24, 2008)

Here is a version with the mixing valve gone.  I would still like to charge the tanks during house demand if possible.  I also changed the zone supply/returns to closely spaced tees which hopefully helps the primary pump not interfere with the secondary pumps.  However, what does the charging pump do during this time?  Will it tend to push water in series along with the primary pump, or will it send water into the tanks.  When this pump is down, water will flow through the tanks in reverse, but when the charging pump is on, water will flow from red to blue as shown (I think).  Where does a check valve or balancing valve belong in the system to insure proper flow direction.  I'm starting to get dizzy with all the flip-flopping.


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## verne (Jan 24, 2008)

what do you guys think of this pipeing scheme ? This is the first I have tryed to post pictures .


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## verne (Jan 24, 2008)

Thats exciting something worked for me. I'm still learning the computer thing. Buy the time I type this post it will be on another topic.The tank is 1000 gal propane , expansion tank xtv 160, 80 gal. termavor mix valve. Taco 007 pump? 140' from boiler to boiler with 1" timesaver . Please ,any advice is greatly appreciated. Im starting to move some earth for my pole barn pad this weekend.I cant wait to get this project going


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## Nofossil (Jan 24, 2008)

verne2 said:
			
		

> what do you guys think of this pipeing scheme ? This is the first I have tryed to post pictures .



2 suggestions: attach a higher resolution / larger image, and start a new thread for discussion on your system. I'd be glad to comment, but I can't see enough detail and I don't want to hijack the original thread.

Thanks....


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## Nofossil (Jan 25, 2008)

tuolumne said:
			
		

> Here is a version with the mixing valve gone.  I would still like to charge the tanks during house demand if possible.  I also changed the zone supply/returns to closely spaced tees which hopefully helps the primary pump not interfere with the secondary pumps.  However, what does the charging pump do during this time?  Will it tend to push water in series along with the primary pump, or will it send water into the tanks.  When this pump is down, water will flow through the tanks in reverse, but when the charging pump is on, water will flow from red to blue as shown (I think).  Where does a check valve or balancing valve belong in the system to insure proper flow direction.  I'm starting to get dizzy with all the flip-flopping.



This is simpler and better, I think. If you redraw it with the tanks placed vertically where the red vertical line is (at the left of the left tank) I think it's easier to understand: 2 loops, each with a circ. Both loops always flow clockwise. The left loop is boiler to tank and back. The right loop is tank to zones and back. Draw it so that there's a T at the top of the top tank and the bottom of the bottom tank, but exact same connections as you have shown.

If the boiler circ is bigger than the secondary loop circ (and I think it should be), then the flow from that is split between going through the tank top-to-bottom and feeding the secondary circ. For instance, if the primary is 20 gpm and the secondary is 10 gpm, then you'd get 10 gpm going into the tank from the boiler. Boiler circ shuts off, tanks flow opposite direction at 10 gpm.

You might need to add a bit of flow restriction to the secondary loop. Your heat load probably doesn't require a very high flow rate.


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## verne (Jan 25, 2008)

sorry wouldnt want to highjack a topic . maybe i should call it boiler piping schematic with pressurized storage#2


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## tuolumne (Jan 25, 2008)

OK, here is an identical schematic with the tanks moved for clarity.  Are you suggesting that if pump A is larger than pump B, the tanks will always be charging even when pump be is circulating to the house zones?


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## Nofossil (Jan 25, 2008)

tuolumne said:
			
		

> OK, here is an identical schematic with the tanks moved for clarity.  Are you suggesting that if pump A is larger than pump B, the tanks will always be charging even when pump be is circulating to the house zones?



I'm really hoping someone who knows what they're talking about will jump in so I can stop making this up as I go along......

Yes, if A is bigger than B the tanks will charge all the time.

There might actually be a slightly more elegant solution. Thinking out loud here:

Going back to your first schematic, grab the mixing valve and make it a real mixing valve - hot and cold inlets, controlled outlet. Install the mixing valve to the left of the secondary pump inlet. Connect the cold water return line to the cold inlet of the mixing valve. With me so far?

If you set the mixing valve for a temp of say 170 degrees, that would be plenty hot enough unless your 'typ' zones are marginal. If you did that, then the flow is balanced and the percentage of the boiler output that goes to the heat loads varies with demand. If the DHW is ice cold, then a high percentage of the boiler output would flow through the secondary loop. If only a single zone was calling for heat, then most of the boiler flow would be through the tanks.

I think that would work, and I think it accomplishes what you were shooting for in the first schematic.


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## tuolumne (Jan 26, 2008)

I'll try to draw this up.  My wall panels are sized for 140 degree supply water on the coldest day, so the whole primary loop need never be above 140.  Do they make outdoor reset type mixing valves?  In mild weather, I could run my storage all the way down to 100-110 probably.  Is it even necessary to go the outdoor reset route?  I can let the tanks run down anyway and a mixing valve wouldn't care.


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## Nofossil (Jan 26, 2008)

tuolumne said:
			
		

> I'll try to draw this up.  My wall panels are sized for 140 degree supply water on the coldest day, so the whole primary loop need never be above 140.  Do they make outdoor reset type mixing valves?  In mild weather, I could run my storage all the way down to 100-110 probably.  Is it even necessary to go the outdoor reset route?  I can let the tanks run down anyway and a mixing valve wouldn't care.



That's even better. At 140 degrees, the mixing valve would allow you to get the best of both worlds - heating storage to a high temp while returning relatively cold water to the boiler. I like it a lot.

You could skip the outdoor reset, I think. Worst case is you run cooler water through your wall panels. If you put a few temp sensors on your tanks, you could get a really good sense of when you'd have to build another fire.

This is more elegant than my approach in the sense that there's no sharp transition between heating with the tank vs. heating with the boiler. The boiler doesn't have to care at all about what's going on with the zones and vice versa.


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## tuolumne (Jan 26, 2008)

Thanks for getting me past that plumbers' block nofossil.  Here is the simplified version, with a mixing valve to send 140 degree water through the primary loop.  The varying amounts of return water diverted back to the zones will cause the boiler pump to charge the tanks all of the time.  Back to some of the original questions...where do I need check valves, isolation valves, drains etc.  Where in this scheme should I put tees for a future fossil fuel backup? 

I just thought of a small problem...I would still like the indirect DHW to get supply water as hot as possible.  Also, I may be putting a hot water unit heater in the garage at some point, and when I want it on it will be with little notice and also need hot water.  Just when I thought I could see bottom the water starts getting murky again.


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## Nofossil (Jan 26, 2008)

tuolumne said:
			
		

> Thanks for getting me past that plumbers' block nofossil.  Here is the simplified version, with a mixing valve to send 140 degree water through the primary loop.  The varying amounts of return water diverted back to the zones will cause the boiler pump to charge the tanks all of the time.  Back to some of the original questions...where do I need check valves, isolation valves, drains etc.  Where in this scheme should I put tees for a future fossil fuel backup?
> 
> I just thought of a small problem...I would still like the indirect DHW to get supply water as hot as possible.  Also, I may be putting a hot water unit heater in the garage at some point, and when I want it on it will be with little notice and also need hot water.  Just when I thought I could see bottom the water starts getting murky again.



You've sketched exactly what I was thinking. I'd make a drawing change to make it more intuitively obvious what's going on - I'd put the tanks one above the other, with the cold connection below the bottom tank. The tanks participate in both loops - te left loop with the boiler, and the right loop with the heat loads. If they 're drawn in the middle that way, it makes the two loops more obvious, and it also clarifies the thermal stratification. Ideally, you'll have a sharp thermocline that moves downward through the tanks in sequence as you put in heat, and moves back upwards as you withdraw it. I don't know how much you can avoid mixing, but commercial systems go to great lengths to promote stratification. Pipe fitting selection and location might be all you can do.

Now that you've made the drawing change, move the expansion tank out of the way and stick a fossil fuel boiler in there with its own circ drawing from the cold return, so that it's in parallel with the tanks and the EKO.

Both boiler circs need check valves. I'm hoping that the secondary circ won't suck water through the boiler(s). Probably the best approach is to plumb it so that it has an independent connection to the top storage tank.

I like an isolation valve on each side of each boiler. Make sure you have a relief valve inside the isolation valve. Boilers have their own drain valves, You probably want isolation and drain valves on the tanks too.

Perhaps you could move the DHW loop so that it straddles the mixing valve. I'd also consider if possible setting up a sidearm HX for the DHW, probably in the hot supply line just to the left of the top storage tank. That way, any time that either boiler is running, your DHW tank is getting superheated (you DO have a tempering valve, right?). The DHW circ will only run when the DHW tank drops below its setpoint. My DHW hasn't called for heat since October.

If you're heating a remote load such as the garage hot water, use 1/2" pex. For intermittent loads, the loss from the slug of cold water that you have to push through can be a big deal.


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## tuolumne (Jan 26, 2008)

Regarding the superheated DHW...I have an 80 gallon tank that's about 6 feet tall, so locating above the boiler is not an option.  Are you suggesting that a sidearm could be installed on this tank to thermosyphon hot water into the tank even when the tank is not calling (pump is not running for DHW zone)?  I would probably have the tank thermostat set at 120, so as not to run the pump endlessly if my storage tanks are cooled off.


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## Nofossil (Jan 26, 2008)

tuolumne said:
			
		

> Regarding the superheated DHW...I have an 80 gallon tank that's about 6 feet tall, so locating above the boiler is not an option.  Are you suggesting that a sidearm could be installed on this tank to thermosyphon hot water into the tank even when the tank is not calling (pump is not running for DHW zone)?  I would probably have the tank thermostat set at 120, so as not to run the pump endlessly if my storage tanks are cooled off.



Yeah - a sidearm is attached to the side of the DHW tank. An inner pipe connects the DHW inlet and outlet. The outer jacket is plumbed in series with your boiler output so that any time the boiler is running, hot water is flowing through it. The water in the DHW tank then thermosiphons as long as it's cooler than the boiler output. I think it's important to have the tees set up so that DHW demand doesn't just draw through the sidearm instead of the tank. Eric's the expert on this. There are a few sidearm threads.

The benefit is that it keeps your DHW 'topped off' automatically. If you have 80 gallons at 180 degrees, that should last a good long time even if you have to mix it with 50 degree well water. I actually use two mixing valves in sequence to mix my hot water - well and preheated gets mixed to 115 (or as hig has the preheat coild supplies). The output of that gets mixed with DHW tank water to produce 118 degree hot water for the house. If my preheat coil is hot enough, I don't touch the DHW tank hardly at all.

You probably want to have some circ inhibit aquastat that shuts down circulation in general when there's no useful heat. It might also illuminate an indicator in the living space that says 'build a fire, dummy'.


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## Eric Johnson (Jan 26, 2008)

Isn't your tank thermometer your "build a fire, dummy" indicator, nofossil?

Good description of the sidearm. You don't touch the inlet and outlets on your hot water heater (the pipes going into the top of the tank) when hooking up a sidearm. All you need to do is connect the sidearm to tees in the pressure relief valve outlet and the drain. That's it. Water enters and exits the tank the old fashioned way.

The beauty of sidearms is their low cost and simplicity of operation and maintenance (no extra pump; no moving parts). Basically, you hook it up and forget about it.


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## Nofossil (Jan 26, 2008)

tuolumne, could you post the part number and source for the Danfoss thermic valve that you show?


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## Bob Rohr (Jan 26, 2008)

I'm not seeing a means to pull temperature from the buffer tanks without flowing through the boiler?

 hr


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## Nofossil (Jan 26, 2008)

master of sparks said:
			
		

> I'm not seeing a means to pull temperature from the buffer tanks without flowing through the boiler?
> 
> hr



When the boiler is cold, there's no flow in the left loop. Flow is from the top of the tanks through the mix valve through the secondary pump (the horizontal one) and out through the secondary loop. The return comes back to the mixing valve as needed and to the bottom of the tanks. I'm hoping it gets redrawn to make it easier to see - it takes a minute to realize that there are really two distinct loops.


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## Donl (Jan 26, 2008)

With reference to Tuolumne's schematic, if Pump A is running and Pump B is not, will there be any flow through B? I guess a better way to phrase my question is how much resistance to flow does an idle pump present?


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## Bob Rohr (Jan 26, 2008)

What turns on pump "A"?  Does it turn on with the 140f control on the EKO?  If so what if the tanks are at 180F and the boiler hits 150F from a cold start?

Also, depending on the flow pattern through that 3 way zone valve it LOOKS like the two pumps will be in series when the ZV flows straight though?

Also what causes flow into the buffer tanks?

Here is a picture of a typical 3 way zone valve, motor removed.  The ports are A on the left, B on the right and AB out the bottom.  Flow can be A to AB, or B to AB.  There is no means for flow from A to B.  I'm not seeing how that flow pattern fits your piping?  Unless you have a 3 way with different flow patterns?

Really your only primary secondary is where the zones take off.  The boiler to buffer and to the right hand loop are not P/S.  Only connection via closely spaced tees allows a true primary secondary.

I still feel a true P/S with all the loads, buffers, boiler, and additional supplemental boilers, connected via closely spaced tees allows the most options.  It allows boiler only to the loads, buffer only to the loads, boiler and buffer together to the loads, supplemental boiler to load only, or virtually any combination of loads and  supplies to work smoothly and without having pumps in series.

And of course you never want the supplemental boiler to flow through the unfired wood boiler, or really a hot buffer tank to flow through an unfired boiler as it will remove a portion of the energy and lose it to the room and the great outdoors via the flue.  And probably you would not want to flow the supplemental boiler through the buffer tanks,  Energy stores much better in the fuel, in the chemical form then it does in hot water.  Unless you have the ability to load the buffer with an electric boiler on off peak KWH rates.

 hr


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## Bob Rohr (Jan 26, 2008)

Forgot the 3 way pic


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## Nofossil (Jan 27, 2008)

master of sparks said:
			
		

> What turns on pump "A"?  Does it turn on with the 140f control on the EKO?  If so what if the tanks are at 180F and the boiler hits 150F from a cold start?



I'm assuming pump A is controlled by the EKO controller. Why would you build a fire if the tank was at 180? If you did, you'd be pushing 150 degree water into the tank, assuming that there wasn't enough demand from the secondary loop to take all of the flow from pump A.


> Also, depending on the flow pattern through that 3 way zone valve it LOOKS like the two pumps will be in series when the ZV flows straight though?
> 
> Also what causes flow into the buffer tanks?



As I understand it, that's not a 3 way zone valve - it's a mixing valve. It has a hot in, a cold in, and a mix out. It will balance the two inlets to achieve the desired outlet temp, just as with the Danfoss that he's using for boiler inlet protection.

Because it's a mixing valve, it will have the effect of limiting flow from the hot inlet most of the time. Unless there's an enormous heat load from the zones, a good portion of the output will be recycled from the inlet. It's set for 140 degrees, and the hot inlet will always be hotter than that if pump A is running. Therefore, the excess output of pump A goes into the tanks.

The two pumps would be in series in effect on a really cold start. If the boiler outlet is 150 and the zones are cold, the mixing valve will almost be a straight connection from hot inlet to mix outlet. That would be the desired behavior.


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## Bob Rohr (Jan 27, 2008)

What are the temperature requirements of the heating loops?  I'd guess you want 160F or more if the heating emitter are baseboard or fan coils.  Maybe 140F for panel rads. 

So the upper thermostatic valve would be set to 160, let's say.  Really the indirect would be better back at the boiler loop via closely spaced tees for the hottest, quickest supply.  If the upper thermostatic is set to 180 so the indirect tank could get plenty of BTUs, then why have a thermostatic there at all if 180 is desired for all the high temperature loads?

I'm still unclear on how or what regulates the flow through the buffer?  And does the flow direction change through the buffer when the boiler circ is off to "unload" any heat from the buffer?  Or will the buffer always run at the boiler temperature?  The pressure drop through the upper 3 way will always be higher then the pressure drop through the buffer.  Seems like a balance valve may be needed to assure the 3 way gets enough flow to supply it's loads?

I guess what is needed is some temperature numbers and required gpm through the various circuits to really get clear on flows at various loads on or off.

 hr


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## Nofossil (Jan 27, 2008)

master of sparks said:
			
		

> What are the temperature requirements of the heating loops?  I'd guess you want 160F or more if the heating emitter are baseboard or fan coils.  Maybe 140F for panel rads.
> 
> So the upper thermostatic valve would be set to 160, let's say.  Really the indirect would be better back at the boiler loop via closely spaced tees for the hottest, quickest supply.  If the upper thermostatic is set to 180 so the indirect tank could get plenty of BTUs, then why have a thermostatic there at all if 180 is desired for all the high temperature loads?
> 
> ...



As described in an earlier post in this thread, he only needs 140 for all loads in the secondary loop except DHW. Looking at different approach for DHW. At 140, the mixing valve controls flow to the buffer. The secondary pump should ensure that enough flow is pulled from the primary loop.


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## tuolumne (Jan 28, 2008)

Wow, there has been a lot of discussion while I was away!  There are two distinct loops.  Regarding the situation where the buffer is at 180, I would not likely be lighting a fire under those conditions.  Pump A is controlled by the boiler, and always runs when the boiler is producting water hotter than the setpoint.  The purpose of the "balancing valve" on the boiler loop is to restrict flow somewhat.  This will ensure that pump B circulates through the buffer and not the outer loop.  Retrieval from the buffer draws off water in reverse, taking the hot water off the top first.  I'm going to attempt a drawing incorporating the sidearm.  I have never seen one, but my plan would be to have an outer shell of 1-1/2" copper that has a 1-1/2x1-1/2x1-1/4 tee at each end tying it out to the main 1-1/4" loop.  In each tee would be a 1-1/2"x1/2" reducer.  A 1/2" pipe would run through the middle and into the drain/pressure relief as Eric described.  Is 1/2" big enough for the inner?  Is my description of the construction correct?  I am also going to try stacking the buffer tanks in reality, so I'll draw them that way too.

Edit: for whoever asked, I got the Danfoss from Mark at ahona, I think he gets them from mcmaster.


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## tuolumne (Jan 28, 2008)

OK, here is the mod.  I am mostly explaining this to myself; you experts please chime in.  If these assumptions are incorrect, please let me know.  Any time the boiler is charging the storage tanks, water flows through the sidearm.  When the boiler is cold, water will circulate through the loop marked with red arrows.  As the Danfoss hits 140 and starts to open up, water begins to follow the light blue arrows and begins to charge the buffer tanks.  If any zone calls, pump B will begin which causes water to follow the path of the green arrows.  The mixing valve would be set at 140 degrees since that would supply the highest demand for those zones.  The DHW and fan coil would always get water however hot the buffer or boiler has to offer.  If the demand is low (one small zone calling) some return water will be drawn back into port Z of the mixing valve.  The reduced demand at port X would cause some flow from the boiler to divert through the buffer along the light blue path.  When the boiler grows cold, pump A will stop.  When zones call, pump C will draw water from the buffer tanks along the path of the black arrows.  Does this all work?


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## Bob Rohr (Jan 28, 2008)

Looking better.  A few thoughts.  I'd move the air purger before the bypass.  While not a huge deal it would see the highest temperature (best air removal spot)  and be a good location for the point of no pressure change (expansion tank connection). 

 If your DHW is the most critical load, pull it right off the boiler as another parallel loop.  Prioritize it with a double pole relay to shut down any other loads until it is satisfied.  It will perform best with all the boiler flow flow and the hottest possible supply temperature.   Unless it is a huge tank, 100 gallons or more, it shouldn't hold the boiler in condensing mode too long to be a problem. You could probably lose the sidearm also with a priority DHW zone.  Cost saving if nothing else.  And some of the indirects are not rated for the high temperature the sidearm may supply.

Remember for the closely spaced tee (loads) the pump down stream will need to run to assure a constant supply of hot water across those tees.  Elsewise it will just recycle the same temperature.

Do you have all your volumes calculated to size the expansion tank?

When will you start the piping?  You put some serious thought into the plan


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## tuolumne (Jan 28, 2008)

Thanks.  The pressure tank is sized for all of my volume.   It has a 1-1/4" connection, so I tied it in adjacent to the air purge, but I can run out of the bottom of my air purge with a smaller pipe and transition at the tank.  I can't move it closer to the boiler, because the high point in my system is actually  right where I show the air purge.  I have some 3D sketches, but they're too big to post when I scan them.  I want the water heater set at 110 or so since I will also have a fossil fuel tied into the same primary loop - I thought it would be just before the DHW, and just after the radiant zones, therefore skipping the buffer tanks.  The sidearm would allow me to keep the DHW at a higher temperature most of the time without running an extra pump to do it.

Pump B will always be running when the zones call.  Does that satisfy the needs of the closely spaced tees?

I'm wrapping up the heat distribution now, so I'll probably start piping the boiler later this week.


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## Bob Rohr (Jan 28, 2008)

The one nagging question I can't seem to get straight is the flow through the buffer.  In my mind I see to potential for flow as shown in my green arrow, and flow around the system mixing valve in red.

Water is lazy and takes the path of least resistance.  I'm not understanding the dynamics to induce some, if any flow to the red loop from the boiler/ buffer loop.  The flow through the mix valve will depend on the % it is open at a given time.  If it sees 180 on the hot side, for instance, it will blend cooler return to try and target that 140.  In that mode you will have little or any flow between the green and red loops.  It may not be an issue?  But the loads between those two loops may not do much (DHW and Garage)

I understand this is a common "wood boiler" schematic, I still feel a true P/S as I showed on my sticky post really address ALL the hydraulics at any given time and assures everyone is satisified and balanced. 

I'd consider a flow setter, or at least a globe valve in the piping to the buffer to allow some restriction to be introduced IF you don't get enough flow to the red loop.

Also check protection on all takeoffs to the heat load and radiant load.  I use the circ with built in checks on one side and a soft seat check on the return.

I calculate 8 gpm at about 4 feet of head for the boiler circ (20 degree delta T).  A Grundfos 15-58 on speed two.  Same for the system pump.  Zone pumps need to size to the gpm and pressure drop.  Possibly on speed 1?

 hr


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## tuolumne (Jan 28, 2008)

Right, if the DHW is calling, pump B is running.  However, the other zones are using any hot water, so pump B starts cycling in the red loop endlessly.  Oops.  If I move the pump to the left of the hot demand zones (actually drawn this way in my 3D layout) the mixing valve won't work right....will it?  I almost need a primary seconday loop off the primary loop....too many pumps gobbling up kilowatts.  I don't really care about my radiators running short cycles at 180 degree water as much as charging the buffer at the same time when heat is available.  With your primary/secondary diagram, I don't see how I can draw off the buffer in reverse for retrieval.


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## Nofossil (Jan 29, 2008)

tuolumne said:
			
		

> Right, if the DHW is calling, pump B is running.  However, the other zones are using any hot water, so pump B starts cycling in the red loop endlessly.  Oops.  If I move the pump to the left of the hot demand zones (actually drawn this way in my 3D layout) the mixing valve won't work right....will it?  I almost need a primary seconday loop off the primary loop....too many pumps gobbling up kilowatts.  I don't really care about my radiators running short cycles at 180 degree water as much as charging the buffer at the same time when heat is available.  With your primary/secondary diagram, I don't see how I can draw off the buffer in reverse for retrieval.



My thought is that this is not a problem. First scenario: everything is cool, no flow. 3-way is open x>y, because it wants to be at 140. DHW demand kicks in. Pump B and the DHW pump come on. The water coming out of the DHW zone is below 140, so the 3-way stays open x>y. All good.

Next scenario: Everything is really hot, no demand in red loop. 3-way is almost straight z>y. DHW demand kicks in. At first, DHW mostly recirculates, but there is always some flow through the 3-way since the red loop is at 140 and has to be losing something. as soon as a bit of the cooler water hits the 3-way, it flips to x>y. This scenario is worst case, and wouldn't likely happen in real life if you had the sidearm, since the only way that everything would be hot is if you'd been circulating hot water, which would have heated the DHW via the sidearm. 

Probably makes sense to have the DHW and garage taps near the 3-way to minimize this potential problem.

In my world, the DHW hasn't had to call for heat since October. Family of five with frequent company, 40 gallon indirect.

My Superstor has no problems at 160+ degrees, but it would be prudent to make sure your indirect is OK up to 180 or so. I'd not move the DHW zone over to the boiler loop since you'd want to be able to heat it from storage.


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## tuolumne (Jan 29, 2008)

I am not sure the sidearm will work now that I've laid out the equipment.  I need to run my main loop way out of its way to do the sidearm.  I have a superstor ultra 80 gallon tank.  My plan is to pipe in the boiler loop which is known and get my tanks set to see where things are at.  I need some concrete progress to help clear my head!


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## Nofossil (Jan 29, 2008)

tuolumne said:
			
		

> I am not sure the sidearm will work now that I've laid out the equipment.  I need to run my main loop way out of its way to do the sidearm.  I have a superstor ultra 80 gallon tank.  My plan is to pipe in the boiler loop which is known and get my tanks set to see where things are at.  I need some concrete progress to help clear my head!



Yeah, I feel like it's time to start building. A sidearm is great if you can do it, even if it can't be at the optimum spot in the primary loop. Any time that water is going through it that's hotter than the DHW, you're getting heat. It's one of the things I wish I'd done. Instead, I have a relay that opens my DHW zone valve when I have some extra heat, and heats it to 160. That works, too.

Biggest reason for obsessing about hot water: that's what will gate your fire interval and/or use of fossil. You may be able to get usable heat out of your radiant and panels with storage temps below 120, but that's marginal at best for heating DHW. When you run out of DHW you'll hear about it.

Your drawing doesn't show your future fossil boiler, but I assume that you're comfortable with putting it in parallel with the EKO with its own circ. The only reason that I bring it up again is that you would want to make sure that the EKO circ has a check valve so that water isn't pushed backwards through the EKO when the fossil is running. In the 'as drawn' without the fossil, that check valve would not be necessary.

By the way - do you have a part number / source / rough price for the Danfoss?


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## Bob Rohr (Jan 29, 2008)

Yeah, I agree you are on the verge of over thinking the system.  Every system could, or should be tailored to the owners needs wants and desires.  Many way to accomplish your goal.

It helps to define how much DHW, how fast, and how often.  My 80K Lochinvar Knight LP boiler will keep up with my shower running non stop.  for many a 2- 2.5 gpm DHW flow is plenty.  Really no need for a lot of storage in my case.  I have solar preheat on all my systems, and the house has a dual coil 60 gallon tank for solar assist and boiler back up.  All summer long the boiler is shut down.

DHW via wood heat is or can be more involved if you want to cover all the options for hw, buffer, multiple heat sources.

The same holds true for your heat loads, what are they on design day.  with tht info pump, mixing valve, needed storage, burn cycles, etc can be calculated and designed around.

Like most on this list I tinker and experient also.  I've built plenty of trial and error HX systems over the years.  I have learned that you can pretty much define and build most systems on paper to accomplish exactly what you need them to do.  It cuts down on the solder and un-soldering phase.

I am impressed with nofossils control system.  It is key to a well behaved hydronic system.  The more data and the more ability to react and change the more efficient your system will operate.

Mild to wild are with plenty in between with system design and installation.

Stop thinking and start soldering.  Nothing you plan on doing can't be re adjusted and tweaked later.

Here is my current approch with a EKO 40, circular primary loop, 500 gallon Lp storage and a few setpoint and differential controls to load and un-load the various components.  The onboard 140F control in the EKO protects the boiler from cool returns, no thermostatic valves used any where.  A variable speed outdoor reset control, on a 15-42 Grundfos circ adjusts the temperature to the radiant slab zones in the shop and office.

Solar gets added as I score take-off freebie panels.  so far 1- 4X10 does DHW preheat.

 hr


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## Eric Johnson (Jan 29, 2008)

Hot rod, yours is the second pro installation I've seen on this board that has the chimney extending down to the boiler exhaust outlet. Most of use black stove pipe. What's the reasoning behind the extra expense?

Nice to see I'm not the only one who parks tools on his boiler.


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## Nofossil (Jan 29, 2008)

Impressive system, MOS!

What is the 'onboard 140 F control' on the EKO that you refer to? Mine has no such thing, and my sense of elegance is offended by the bang-bang control system that I have at present (using a zone valve). I'm adding a multiple speed pump (Grundfos under computer control) to help, but how else could you do it without a tempering valve?


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## tuolumne (Jan 30, 2008)

Nofossil, I got the danfoss from Mark at ahona.  It is 1-1/2" female, but I believe a 1-1/4" is available...I wish I'd gotten that one since the rest of my system is 1-1/4.  It is also available in several pre-set temperatures.  Mine is 140 degrees F.  I think Mark gets them from mcmaster carr.  By the way, he said he is at some farm show in Barre this week.  I don't know how close you are to there.


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## tuolumne (Feb 23, 2008)

I'm finally turning some of the schematics into reality.  This doesn't look like much for a days work, but I'm fairly green at pipe fitting.  The boiler piping is held up on some tees I'm waiting for for the temperature probes.  What you see is the boiler circ pump on the return; that tee on top is just keeping junk out.  On the floor you see part of the primary loop with supply/return lines for the secondarys.  On the right side is the distribution for the two radiant zones.


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## tuolumne (Mar 1, 2008)

Are black fittings weldable?  I have drilled holes in my propane tanks and need to weld on some couplings to connect the piping.


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## solarguy (Mar 1, 2008)

You would weld a schedule 40 nipple on to the tank or weld a threadolet. 
Personally, I like threadolets better.


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## Sting (Mar 1, 2008)

Yes and no Eric! Sacrifice one of your fittings and test it - then again if you begin and fail you can grind the offending weld and fitting off just like Windows Restore.

Flow will be enhanced if you grind a radius inside the tank easing the sharp edges to the outside! But thats a lot of work and most do not care.

I make my own Thread outlets - If you have pipe coupling fitting already in the correct size and they are the type that are not threaded all the way thru - look in side - Do the threads stop in the middle and is there a narrow ring of un-threaded area??  IF YES -- Bravo - quality fitting - if no - all is not lost they work

Cut the coupling in half

Place the cut end to the tank and weld that water tight - Do you weld water tight?? I used to be able to - then I got old  my eyes went south and I shake too much. Poor me - who cares.. Tack one side - weld 1/4 diameter on the fitting on the other  - one inch or what ever is the least length - go back to the other side begin your weld 1/2 inch away from the tack and carry the weld puddle across and well over the tack to bury the it in the new weld. STOP peen your welds. Start in the middle or one inch away from the first full weld and weld to the first weld - do not stop weld over it by 1/4 inch then stop - peen the weld - continue stitching like this welding over the previous to seal each stich to the next and teh last begin on the old and carry the puddle over and past the neighbor.

Fill the vessel with water to within a 1/2 inch of the weld to limit your explosion danger or fill the vessel with inert gas as you weld to prevent flash out - these heavy tanks will likely not shatter if a the old vapor ignites BUT you will be in for a ride if it does - and maybe a little less chest skin,

Hove fun - be safe let us know your OK!

Kind Regards
Sting


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## tuolumne (Mar 1, 2008)

My local supplier has "weldolets", thanks for giving me a clue what to ask for.  Thanks for the details.  The tank has been pressure washed, and I had planned to blow air through it during the welding.  I cannot do water until I get the boiler going, as any water I bring into the house now will freeze.  The well is in, but I havn't dared to bring any water up!  I could run tractor exhaust through the tank and back outside if that would be better than air.  Opinions?


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## Sting (Mar 1, 2008)

Place the flame of a small propane torch in the exhaust stream of the tractor and MAKE SURE that the propane flame does not enhance the products of combustion because the donor vehicle is running rich. IF the propane torch is extinguished - so much the better.  but try till YOUR satisfied. I have welded tanks using exhaust gas from a know good source like this but you must trust that source - 

Think of it like this - if you pressurize a tank to 30 psi of water - and a weld ruptures - you get a big leek and a little splash. but if you pressurize it with the same PSI of air - you can expect the same result as when the tire on your truck blows out at 30 PSI  BIG BANG...

Liquid is always the preferred safety  for this - but work arounds are necessary for some things

put as much pipe on the exhaust as you can to cool the stream before switching to flexable hose or the exhaust heat could melt the hose and you will suddenly loose your gas shield in the tank


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## Sting (Mar 1, 2008)

I know some will read this and wonder why I suggest the precautions

Its because I got this old!


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## solarguy (Mar 1, 2008)

I'm not sure about blowing air thru the tank while welding to disipate residual propane fumes.

We fill existing propane tanks up with water, then drain them prior to even drilling holes in them let alone welding. During the fill process, any residual propane fumes get purged from the tank. 
Once you drain it any residual liquid is history, you are 99.9% assured you are not going to blow up


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## tuolumne (Mar 1, 2008)

Is the residual liquid history?  The tanks have been filled, drained, and a pressure washer stream played around the inside.  Since then they have sat for more than a year.  I have been told that the steel is porous enough to retain some of the propane.  Will proceed as safely as possible.......


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## Sting (Mar 1, 2008)

tuolumne said:
			
		

> Is the residual liquid history?  The tanks have been filled, drained, and a pressure washer stream played around the inside.  Since then they have sat for more than a year.  I have been told that the steel is porous enough to retain some of the propane.  Will proceed as safely as possible.......



Good - rumor is correct - I have been flashed from some very old tanks open for a very long time because I was stupid and didn't take the time to correctly do a RUSH job  :>)


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## steam man (Mar 1, 2008)

I have cleaned and certified many large industrial fuel tanks for welding. In my liquified natural gas days I had to test for combustibles many times. I know the "little guy" at a small shop does not have the resources for testing and will resort to the above schemes mentioned. I think you are probably 99.99% safe with all the prep work that has been done. Its the unknown that's risky and many welders have learned it the hard way. The only proper way to do this is to have the tank tested with a combustible gas detector to know exactly what the atmosphere is inside the tank.  Aside from that, filling it with water would be the next safest situation.


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## solarguy (Mar 1, 2008)

I'm not sure about anything other than I'm dam sick of snow

When we've filled the tanks w/ water & drained them I've always taken a wiff before proceeding. 
For what's it worth, the nose knows. 
If you fill & drain a tank & still smell propane, fill & drain it again or all bets are off.


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## tuolumne (Mar 4, 2008)

I had some more time to work on the boiler this afternoon.  I now have the supply, return and bypass piped at the boiler.  The danfoss is visible at the rear, with a balancing valve on the bypass.  I have a temp/pressure gage on the supply, and a temperature gage at the return.  I also built the sidearm today.  Once I got more pipe layed out, I realized that the sidearm would only take a few extra feet to tie in.  I used 1-1/2" outer pipe (boiler loop is 1-1/4) with a 3/4" pipe on the inside.  This connects the cold inlet and hot outlets of the indirect storage tank.  I had to ream out the stop in the reducer coupling to get it to slide over the 3/4" pipe.  The picture at the bottom of the tank shows the cold coming in, the bottom of the sidearm and a drain.  At the top you can see the mixing valve to temper domestic water.  The valve to the left is to supply untempered water to the dishwasher.  The domestic loop still held pressure when I was done, so that's a good sign!  I put a valve at the top of the thermsyphon loop...I was worried that water might jump directly from the cold supply to the hot without going through the tank.  Tank outlets are 1-1/2", versus 3/4" in the sidearm, and the valve will let me sqeeze it down to a very small orifice.  Any comments?


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## tuolumne (Mar 14, 2008)

I finally have the boiler all piped and tied into the house distribution.  I still need to either tie out to a gravity overheat loop.  Does anyone know of an online source for an automag valve?  I also need to pipe the storage buffer tanks...waiting for warmer weather so I can fill with water for welding and leave them that way.  I just got my box of electrical goodies today, so that's the next challenge.  I have a radiant mixing block that controls the radiant zones, a zone valve controller, and a switching relay for the other pumps.  I need to make sure that all of these components can get along with each other and the EKO as well.  the four valves going to nowhere are for the bufer supply/return, and for a future fossil fuel boiler that I hope I'll never need.  I had asked previously with no response...what can I use to read thermocouples or RTDs or something on wire for temperature measurements in the buffer tanks...human readable that is?  I plan to use a capped copper pipe in each tank.  Should I stuff insulation between the gauges to prevent convection in the pipe?


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## jebatty (Mar 14, 2008)

check http://www.automagzonevalve.net/


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## tuolumne (Mar 14, 2008)

Thanks for the link Jim.  They told me that my local F.W. Webb has them in stock.  I don't know why my searches came up empty before.


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