# Heat Storage....Finally...!!!



## jpelizza (Feb 3, 2018)

After 6+ years of heating with my 150K Econoburn I'm finally getting storage bank! Can't wait till its all hooked and running.......been wanting this for LOOOOOOOONG TIME

I've been through lots of options on how to do it. I've settled on ordering 1100 gallon unpressurized 88"x88", 54" tall from americansolartechnics.com known on here as tom from Maine...

I'm putting it in my finished basement in a room that kicks out 12x16.

I'm just planning on running 1 1/4 pex from my heat bank to primary loop in utility room. I have radiant heat. I'm thinking of putting one circulator that will run automatically at 90 degrees or more. having two shut offs one for supply and one return by primary loop.

wondering how I get temp readings easily so I know what heat storage is an when I need another fire...

also any ideas how to tie into heat for pool as well.

tom helping get this all straight too but will take any ideas so I don't miss any thing...

thanks...


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## peakbagger (Feb 3, 2018)

I have had a smaller AST tank for several years. One suggestion is to put dricore under the base insulation https://www.homedepot.com/p/DRIcore...core-Subfloor-Panel-CDGNUS750024024/202268752. This prevents any possibility of water pooling underneath the base. I put the base foam right on top of it.  

Temp readings are easy. RTD type temperature readouts are cheap, you can mount RTDs in the foam making sure that its taped over before you put the liner in. Tom supplies a copper cap to put on top of the vent pipe. I put a slice in mine and have an aquatrol bulb hung down the vent pipe and also a type K thermocouple stuck down next to it. The only important temp you need is the top of the tank temp as the rest of the tank stratifies. 

Tom warns you that the top of the tank can not be used for storage yet there is quite a bit of space above it. I built a set of wooden frames that are attached to the floor rafters above it and then have a removable deck that lays across the supports. I had to replace a liner at one point after it was in place and with the decking removed it didnt get in the way.


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## warno (Feb 3, 2018)

To answer the temperature reading question, I went with some cheap temp display units from eBay. They were discussed here in a thread not that long ago. Here's the thread 

Here's a pic of mine.


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## jpelizza (Feb 4, 2018)

peakbagger said:


> I have had a smaller AST tank for several years. One suggestion is to put dricore under the base insulation https://www.homedepot.com/p/DRIcore...core-Subfloor-Panel-CDGNUS750024024/202268752. This prevents any possibility of water pooling underneath the base. I put the base foam right on top of it.
> 
> Temp readings are easy. RTD type temperature readouts are cheap, you can mount RTDs in the foam making sure that its taped over before you put the liner in. Tom supplies a copper cap to put on top of the vent pipe. I put a slice in mine and have an aquatrol bulb hung down the vent pipe and also a type K thermocouple stuck down next to it. The only important temp you need is the top of the tank temp as the rest of the tank stratifies.
> 
> Tom warns you that the top of the tank can not be used for storage yet there is quite a bit of space above it. I built a set of wooden frames that are attached to the floor rafters above it and then have a removable deck that lays across the supports. I had to replace a liner at one point after it was in place and with the decking removed it didnt get in the way.




Tom did tell me to put 1" foam under heat bank when I asked him, I like what you sent me link on I'll do that, thanks!
looks like I can get a few temps by looking at what you did and that thread from other post here...

I do want one I can know what it is without going into my basement so either wireless if possible or maybe I can get a baby monitor with screen looking at a read out or something...


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## jpelizza (Feb 4, 2018)

warno said:


> To answer the temperature reading question, I went with some cheap temp display units from eBay. They were discussed here in a thread not that long ago. Here's the thread
> 
> Here's a pic of mine.
> 
> View attachment 222344




thanks!, looks great!, I'll look at that thread...


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## Marshy (Feb 4, 2018)

@jpelizza, I'm in the process of installing a new system in my house and have a 820 gal AST tank. I used the DryCore under my tank, then I put a base layer of 2" rigid foam board down and built the tank on it. If you want to see more of that install you can find it here...
https://hearth.com/talk/threads/froling-add-on-install.163423/


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## BoiledOver (Feb 4, 2018)

Congrats on your storage install, you will enjoy it for sure.

Having more than one temp sensor in storage has benefits. I might have gone overboard but am happy to have all five inputs to determine the fire loads. The five are located at; the very bottom of the first tank (the zero gallon mark), midway up the first tank (the 250 gallon mark), on top of the first tank (500 gallon mark), midway up the second tank (750 gallon Mark), and on the top of the second tank (1,000 gallon mark). The tanks are 500 gallon propane units. This input allows for a very close account of how many btu's are stored and how many pounds of firewood is needed to get to a target amount of btu's in storage.


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## peakbagger (Feb 4, 2018)

I had some spare thermocouples so I mounted them in the tank when I installed the liner. They just terminate with thermocouple plugs on the outside. I have looked at the numbers in the past but came to the conclusion with a single square tank its going to stratify and I am not going to be able to change that unless I circulate the liquid in the tank. Maybe it makes sense for multiple tanks but not really important with an single tank. I realize some folks like to over instrument these systems, but the best approach is KISS (keep it simple stupid).


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## tom in maine (Feb 5, 2018)

One minor suggestion about what goes underneath one of our tanks.
Nothing wrong with something like Dricore, except if there is any dribbling from a fitting or condensation, over time, the OSB is going to fail.
Probably not a big issue, but if you want a drainage plane under the tank, use just the plastic part of the Dricore or get similar material, which is just the plastic (I cannot remember the product name!)

Sitting directly on Styrofoam is still going to allow any wetness to go around it onto a concrete floor.
Here at our shop, where we have a test tank that is not sealed, there are no issues sitting on foam on the floor.

No big deal either way, I am just apprehensive about anything that can decay due to wetness or the  general humidity in the basement that cannot be easily dissipated.


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## NateB (Feb 8, 2018)

This is what I used to get heat out of the tank and into the house.
https://www.supplyhouse.com/Honeywe...5-200F-range-5-30F-Adj-Differential-1738000-p

This is what I use to put heat into the tank.  It has 2 sensors. I put one half way down the side of the tank, and the other sensor I put on the primary loop before the tank tees.
https://www.supplyhouse.com/Tekmar-156-Difference-Setpoint-Control-On-Off-7954000-p

I can give more details if you need.  

I put the one inch of foam under my tank, and since it is in 2 pieces, I would see water coming out of the crack first if I had a leak.


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## peakbagger (Feb 8, 2018)

Without going into details on the cause I got to see tank leaks in person twice on my installation and am glad I had a way of insuring that the air flow could dry the space under the tank.


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## tom in maine (Feb 9, 2018)

To try to put this in perspective. If one of our tanks is wet on the bottom from a wet floor, a leak or condensation from another source,
the tank will dry itself once the issue is gone. A wet tank dries once heat is back in the tank. 
Installing one of our tanks directly on a concrete floor is okay if the floor is dry. If it is damp or wet, there could be some corrosion on the framework.
1" of styrofoam on the floor, to segregate the tank frame from the concrete is prudent.
This being said, I have yet to see any failures due to the tank bearing directly on concrete.

With a layer of foam or a simple poly sheet under the tank protects the base in case some moisture finds it way to the bottom, the corrosion is not exacerbated by wet concrete in contact with metal.

The air space is not critical, but is not a bad idea, for any metal on damp surfaces.


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## jpelizza (Feb 16, 2018)

NateB said:


> This is what I used to get heat out of the tank and into the house.
> https://www.supplyhouse.com/Honeywe...5-200F-range-5-30F-Adj-Differential-1738000-p
> 
> This is what I use to put heat into the tank.  It has 2 sensors. I put one half way down the side of the tank, and the other sensor I put on the primary loop before the tank tees.
> ...



thanks I'm checking all that out!


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## jpelizza (Feb 16, 2018)

Ok trying to figure this out.

Have radiant heat so temps down to 90-100 during day heating , 115-125 nighttime heating..

Planning on running 1 1/4 pex from AST tank to primary loop in utility room...

I'm not sure on this part ... put a 90 degree circulator (its on anytime temp over 90 degrees) on the supply or return to tank near primary loop connection...???

Thought Is run boiler to charge up tank to 180..., turn boiler off, circulator runs heat from AST to primary loop as long as heat above 90 degrees...

Am I close...?

Also want to add another supply/return from primary loop to pool pump area to heat pool in may early June...


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## jpelizza (Feb 16, 2018)

NateB said:


> This is what I used to get heat out of the tank and into the house.
> https://www.supplyhouse.com/Honeywe...5-200F-range-5-30F-Adj-Differential-1738000-p
> 
> This is what I use to put heat into the tank.  It has 2 sensors. I put one half way down the side of the tank, and the other sensor I put on the primary loop before the tank tees.
> ...


 
so does the acua stat then you set at what temp you want it to turn on circulator then??


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## peakbagger (Feb 16, 2018)

I run my storage up to 185 F and then run the water from the heated water from the coil to the radiators when the zone thermostats call for heat until the temp out of the storage drops below 140 F. I have conventional baseboard so Its heating capacity drops quickly after that. Once the storage is below 140 F the tank coil is taken out of the loop. My oil boiler has a lockout relay on the burner so when the storage temp goes below 140, the oil burner turns on and the system becomes a regular run of the mill oil fired hydronic system that any burner tech can diagnose. If I turn the power off to the wood boiler, it also reverts back to an oil system. This complicates the controls a bit as I need to use relays and spring loaded valves to get everything to revert back to a regular oil system. A PLC would be easier but I dont use them as I have past experience with old PLCs and the loss of the ability to program them due to software compatibility.


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## jpelizza (Feb 18, 2018)

I plan to turn propane back up off once I start to burn especially having heat bank..., so I just want simple... do they make circulator that will just pump to primary loop from heat bank above 90 degress...?


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## jpelizza (Feb 18, 2018)

NateB said:


> This is what I used to get heat out of the tank and into the house.
> https://www.supplyhouse.com/Honeywe...5-200F-range-5-30F-Adj-Differential-1738000-p
> 
> This is what I use to put heat into the tank.  It has 2 sensors. I put one half way down the side of the tank, and the other sensor I put on the primary loop before the tank tees.
> ...



Ok looks like that Tekmar I understand a little, I have a Tekmar that runs my radiant heat but looks like this one I hook into circulator that is on heat bank to primary loop, then I would just set it to run at 90+ degrees....right?


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## NateB (Feb 20, 2018)

Tekmar is little bit more complicated.  It has a delta setting, a minimum setting, and a maximum setting.  It compares the temperature of the primary loop with the temperature of the tank.  You don't want to circulate 90 deg water into your 150 deg tank.  The Tekmar is the scavenger of the system it takes the leftover heat and stores it, but if it is cooler it lets the water go back to the boiler to warm up.  This part lets your boiler run full tilt until the wood is gone, and store the heat in the tank.  It also has upper limit protection to keep from over heating your tank.  Which is important because liners do have an upper limit.  I think it is 185, but I never push the temp that high.

The aquastat is in charge of using the heat from the tank, or using heat from your propane boiler.  There are 3 contacts on the aquastat one for power coming in, one to power if the temp is low, and one to power if the temp is high.  The aquastat gets power from a relay that is turned on/off by the house thermostat.  The aquastat only need to know the temp of the tank.  Low turn on the propane circ,  High turn on the tank circ.

Unrelated to the question, but I use a second relay to power the zone circ.


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## TonyVideo (Feb 20, 2018)

I believe there is a sticky on this above the threads in this forum.

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## jpelizza (Feb 21, 2018)

NateB said:


> Tekmar is little bit more complicated.  It has a delta setting, a minimum setting, and a maximum setting.  It compares the temperature of the primary loop with the temperature of the tank.  You don't want to circulate 90 deg water into your 150 deg tank.  The Tekmar is the scavenger of the system it takes the leftover heat and stores it, but if it is cooler it lets the water go back to the boiler to warm up.  This part lets your boiler run full tilt until the wood is gone, and store the heat in the tank.  It also has upper limit protection to keep from over heating your tank.  Which is important because liners do have an upper limit.  I think it is 185, but I never push the temp that high.
> 
> The aquastat is in charge of using the heat from the tank, or using heat from your propane boiler.  There are 3 contacts on the aquastat one for power coming in, one to power if the temp is low, and one to power if the temp is high.  The aquastat gets power from a relay that is turned on/off by the house thermostat.  The aquastat only need to know the temp of the tank.  Low turn on the propane circ,  High turn on the tank circ.
> 
> Unrelated to the question, but I use a second relay to power the zone circ.



I was thinking I would circulate tank down to 90 degrees as my radiant heat will still heat daytime down to 90 degrees.  so thats why I was thinking to have heat bank circulate all the time from 180 down to 90 degrees to primary loop...its night time that radiant calls for closer to 120 degrees...


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## NateB (Feb 21, 2018)

jpelizza said:


> I was thinking I would circulate tank down to 90 degrees as my radiant heat will still heat daytime down to 90 degrees.  so thats why I was thinking to have heat bank circulate all the time from 180 down to 90 degrees to primary loop...its night time that radiant calls for closer to 120 degrees...


Yes you will set the aquastat to 90 degrees, so if the tank gets below 90 it will turn on the circ for the propane, or if it is above 90 it would turn on the circ for the tank. 

Remember the aquastat gets power when the thermostat calls for heat.


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## jpelizza (Feb 22, 2018)

NateB said:


> Yes you will set the aquastat to 90 degrees, so if the tank gets below 90 it will turn on the circ for the propane, or if it is above 90 it would turn on the circ for the tank.
> 
> Remember the aquastat gets power when the thermostat calls for heat.



ok I think that sounds like a plan, i had an aqua stat for propane back up but it stopped working so I just turn propane boiler off now, when I start burning I just want to burn no back up...any ideas on size of circulator?


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## NateB (Feb 22, 2018)

I use grundfos 15-58 fc for the boiler and the tank.  I did not buy those based on any calculation.  I bought those cause that is what fit in the budget.


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## maple1 (Feb 23, 2018)

They are very good circs. The 3 speeds can be very handy at times.


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## jpelizza (Mar 7, 2018)

ok looks like tank is coming Friday i set up delivery time.  

- I'm going to get the aqua stat to turn on/off circulator to and from primary loop to tank.
- going to get grufundos 15-58 3 speed circulator
- will use 1 1/4" pex to and from primary loop to tank
- will put ball valve shut off from primary loop to circulator (circulator will be on pex line from primary loop feeding heat to tank), and one ball valve shut off from tank supply to primary loop.
- on farmtek.com i can get a few wired mini digital meter panel for tank temps.     http://www.farmtek.com/farm/supplie...1&langId=-1&division=FarmTek&productId=910879
- i might just put baby monitor with video looking at tank temps in basement and then i can check tank temps easily from first floor looking at monitor.
-will put 1inch foam and or the plastic from dry core under tank.  my basement is finished floor with click in lay laminent/engineer material
-only other thing i'll need is proper flange for circulator, and pex tool to handle 1 1/4", hopefully i can rent one...

hows this sound?


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## NateB (Mar 9, 2018)

It sounds like you may always be circulating water to your tank until the temp falls below 90 deg.  If your aquastat see 90 deg it will keep pumping till it gets below 90.  If you run your boiler it will start the aquastat, and heat the tank up to 170, and after the boiler stops the aquastat will continue to pump, but the heat will be coming from the tank.


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## jpelizza (Mar 9, 2018)

NateB said:


> It sounds like you may always be circulating water to your tank until the temp falls below 90 deg.  If your aquastat see 90 deg it will keep pumping till it gets below 90.  If you run your boiler it will start the aquastat, and heat the tank up to 170, and after the boiler stops the aquastat will continue to pump, but the heat will be coming from the tank.



That is correct in how I see it as well!, just got tank delivered few minutes ago, hope I can get it up and running soon!
	

		
			
		

		
	








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## peakbagger (Mar 9, 2018)

The box goes together quickly. Moving the liner into place is not as fast. It requires patience and ideally get it warm.


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## jpelizza (Mar 9, 2018)

peakbagger said:


> The box goes together quickly. Moving the liner into place is not as fast. It requires patience and ideally get it warm.



Ok, good to know [emoji106]


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## NateB (Mar 9, 2018)

Put your sensor probes in as you assemble it.  Also the insides of the tanks made me very itchy, like fiberglass insulation, so don't rub against them to much.


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## jpelizza (Mar 9, 2018)

NateB said:


> Put your sensor probes in as you assemble it.  Also the insides of the tanks made me very itchy, like fiberglass insulation, so don't rub against them to much.



All info appreciated thanks!


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## jpelizza (Mar 11, 2018)

This is where tank will be going in basement, getting it cleared out today and will start to assemble tank.

As you can see this spot was mostly storage to summer toys that were in garage but now half of room will be my tank that will store my “ATU’s”....”American Thermal Units”...[emoji2]







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## Marshy (Mar 11, 2018)

You really want that tank liner to be 70F so it's not brittle. Yes the black insulation board does have a fiberglass like layer on it so gloves and log sleeves is a good idea as mentioned. 

You might want to talk with @Chris Hoskin at Tarm about getting a BLT controller. They offer them as a stand alone controller to integrate a primary and secondary heating system. 

My existing zone control on the left for my oil boiler (secondary), the BLT controller on the right. 










These are the low voltage terminals for the BLT (below). You can see the tank aquastat works with the BLT to determine what system should be providing heat to the zones.


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## jpelizza (Mar 11, 2018)

Marshy said:


> You really want that tank liner to be 70F so it's not brittle. Yes the black insulation board does have a fiberglass like layer on it so gloves and log sleeves is a good idea as mentioned.
> 
> You might want to talk with @Chris Hoskin at Tarm about getting a BLT controller. They offer them as a stand alone controller to integrate a primary and secondary heating system.
> 
> ...



Thanks for info!, I’ll look into that but I’m not sure I’m smart enough to understand all of that, maybe after I look at it a few times...


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## jpelizza (Mar 11, 2018)

Room cleaned out, carrying pieces down now...







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## NateB (Mar 23, 2018)

Something I thought of.  If your aquastat turns on your circ at 90F.  You are going to have issues with low return temp to your boiler for a long period of time until your tank get up to 140F.  Returning 90 F water to your boiler will make a mess of your boiler, by keeping the fire to cool and filling your HX with creosote.  Along with many other issues relating to thermal shock and corrosion.

Do you have return protection on your boiler?


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## jpelizza (Mar 23, 2018)

NateB said:


> Something I thought of.  If your aquastat turns on your circ at 90F.  You are going to have issues with low return temp to your boiler for a long period of time until your tank get up to 140F.  Returning 90 F water to your boiler will make a mess of your boiler, by keeping the fire to cool and filling your HX with creosote.  Along with many other issues relating to thermal shock and corrosion.
> 
> Do you have return protection on your boiler?



I do not have return protection...
I would think most times I’ll be firing up another burn well before it’s drawn down to 90 degrees...
Also if that is the case and my boiler gets to say 170 won’t it return say 120-130ish after going through heat exchanger??, wouldn’t think it be all the way back down to 90 returning to boiler...but idk on that so....

Good point for sure! Thx...


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## Bad LP (Mar 23, 2018)

You need boiler protection.


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## maple1 (Mar 23, 2018)

jpelizza said:


> I do not have return protection...
> I would think most times I’ll be firing up another burn well before it’s drawn down to 90 degrees...
> Also if that is the case and my boiler gets to say 170 won’t it return say 120-130ish after going through heat exchanger??, wouldn’t think it be all the way back down to 90 returning to boiler...but idk on that so....
> 
> ...



140 is the magic number. Return temps below that for any periods of time will likely cause creosote condensation.  Especially important when heating storage - usually lots of cool water to get back up to temp.


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## BoiledOver (Mar 23, 2018)

Danfoss has you covered for boiler protection with the ESBE series thermic valve, SEE HERE. And since the element is sold separately, SEE HERE. Or if you prefer, elements with differing opening temps can be had.


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## peakbagger (Mar 24, 2018)

I have the "poor mans" return protection on my old Burnham. I have a temperature switch stuck in the water jacket located at mid level on the boiler. It controls the circulator pump on the boiler so that it wont turn on until the temp goes over 140F. Its also serves at the end of night when the storage is up to temp and the boiler is out of wood to eventually turn off the pump once the boiler jacket drops under 140. Otherwise it just runs as long as the boiler is turned on.


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## salecker (Mar 24, 2018)

Another way to provide boiler protection is with a near boiler pump.
Econoburn recommends this on their boilers.
You need a aquastat and another pump.The pump circulates water in the boiler till you get to your high set temp on the the aquastat, then the pump to storage takes over till your boiler drops to your low set temp.Then it repeats.
 I use this setup as my boiler is in another building without any makeup water.


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## BoiledOver (Mar 24, 2018)

There are several ways to skin the boiler protection cat for sure. Two compelling features to using a thermic valve are; no electronics needed and it is self governing. Start the storage circ at the beginning of the fire and let it do its thing. The valve will circulate through the boiler only until the entire unit is up to temp and then will slowly open as output rises. At 18F above the elements designated temp the valve will fully open. Meaning, if you have a 140F element, when the return from storage hits 158F it will be fully open to and from storage. In summary, it cracks open a bit when the entire boiler is up to 140F and will gradually open further until the return reaches 158F and then will be fully open to and from storage.

As a fourth option. There is also a loading unit which accomplishes the same thing. See one HERE.


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## NateB (Apr 3, 2018)

I used the Danfoss unit that BoiledOver linked to, and I would recommend you put one in.  I do have a question for everyone, because I am not sure what will happen.  If his tank does get low in temp say 100 - 120F, and the boiler is fired.  Will the return protection run choked down for a long time?  I think it will, because all the heat load from the tank will be on the boiler.  Would that make the boiler less efficient, until the tank got to 140F?


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## maple1 (Apr 3, 2018)

NateB said:


> I used the Danfoss unit that BoiledOver linked to, and I would recommend you put one in.  I do have a question for everyone, because I am not sure what will happen.  If his tank does get low in temp say 100 - 120F, and the boiler is fired.  Will the return protection run choked down for a long time?  I think it will, because all the heat load from the tank will be on the boiler.  Would that make the boiler less efficient, until the tank got to 140F?



Not sure exactly what you mean there. But, colder storage (100-120) would theoretically mean that the boiler return temp would be at 140, for a longer period of time. (More supply going around the bypass would mean less going to storage therefore slower to get up above 140 at the bottom). IMO overall boiler efficiency is greater with cooler return temps - that cooler water should pull more heat out of the gasses before they go up the chimney. The effect might be minimal, but I think that's what it is. And also why I run cooler storage than when I first started.


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## Marshy (Apr 3, 2018)

I'm not familiar with all of the return protection devices/methods but I am familiar with mine. Basically, the hot supply from the boiler is mixed with the returning water from the storage so that it is 140F or greater. The upper limit on my boiler jacket is like 200F. So, until the water returning from the storage tank reaches 140F its being being mixed with boiler supply. Once the tank return temp is 140F without mixing the valve will open all the way. My valve is thermostatic just like your car engines thermostat. 

http://www.lkarmatur.com/en/products/thermic-valves--check-valves/lk-821-thermovar_55554462.aspx

Of course, with this kind of valve you will need a small circ pump for the boiler to constantly circulate while the boiler is being fired.


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## maple1 (Apr 3, 2018)

Mine is an LK810. Likely basically same as yours but it has a built in circ. Kinda pricey, but it works great.


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## Marshy (Apr 3, 2018)

maple1 said:


> Mine is an LK810. Likely basically same as yours but it has a built in circ. Kinda pricey, but it works great.


Same principal, just yours has the pump integrated into it. They call those a loading unit.


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## NateB (Apr 4, 2018)

maple1 said:


> Not sure exactly what you mean there. But, colder storage (100-120) would theoretically mean that the boiler return temp would be at 140, for a longer period of time. (More supply going around the bypass would mean less going to storage therefore slower to get up above 140 at the bottom). IMO overall boiler efficiency is greater with cooler return temps - that cooler water should pull more heat out of the gasses before they go up the chimney. The effect might be minimal, but I think that's what it is. And also why I run cooler storage than when I first started.



I agree it would be technically more efficient, but only if it would have enough flow.  I would think it would take a long time for the boiler protection to open if it had 1000 gal of 120f water behind it.  I think it would open a little, close and repeat for a long time.  I don't really know for sure, it would be great to hear what jpelizza  does and how it works for him.


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## Marshy (Apr 4, 2018)

NateB said:


> I agree it would be technically more efficient, but only if it would have enough flow.  I would think it would take a long time for the boiler protection to open if it had 1000 gal of 120f water behind it.  I think it would open a little, close and repeat for a long time.  I don't really know for sure, it would be great to hear what jpelizza  does and how it works for him.


He doesn't have any return protection.


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## maple1 (Apr 4, 2018)

NateB said:


> I agree it would be technically more efficient, but only if it would have enough flow.  I would think it would take a long time for the boiler protection to open if it had 1000 gal of 120f water behind it.  I think it would open a little, close and repeat for a long time.  I don't really know for sure, it would be great to hear what jpelizza  does and how it works for him.



Mine opens a bit & stays there, no off/on effect. 

If you knew what your boiler circ was pumping, you could figure it out. If you had 120 cold from storage, mixed 140 to boiler return, and 160 boiler supply, that would roughly correlate to 1/2 of boiler output going around the bypass and 1/2 going to storage. So if your boiler circ was pumping say 5gpm, that would be 2.5 gpm to storage - 400 minutes for one full lap, at which point your boiler return would go from mixed 140, to 160 not mixed. Which is quite a while. But that number is likely on the low side, maybe. Second lap would be half as long. Depends also if any of your heat is going to loads or not.


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## Marshy (Apr 4, 2018)

It's not worth the mental aggravation to figure thst out because all the while the boiler outlet temp would be increasing as the fire rages inside it. It would be a dynamic change and before long your boiler jacket is 200F and the more heat is being sent to the tank.


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## maple1 (Apr 4, 2018)

I didn't find much at all worthwhile actually figuring out when I was doing my setup. I just winged most of it, seat of pants like, and ended up kinda lucky in some thing I did the way I did. Maybe not the recommended approach.

But I have found that boiler temp stays pretty constant thru the burn, by lap. First lap (2/3 of burn time?), it's 160-165 out, second lap maybe 185 out. dT stays pretty steady at either. Also my fire is burning out part way thru lap 2. It's good to have a 3 speed boiler pump, you can get the dT you want pretty easy, then it's set & forget.


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## Fred61 (Apr 4, 2018)

Marshy said:


> It's not worth the mental aggravation to figure thst out because all the while the boiler outlet temp would be increasing as the fire rages inside it. It would be a dynamic change and before long your boiler jacket is 200F and the more heat is being sent to the tank.



That's right and meanwhile the Danfoss is tempering the flow allowing more system water through as the temperature rises. Efficiency rises as the boiler heats up which allows the fire to burn hotter.


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