Storage plumbing idea and question

[pulse]

So I think I am going to pull the trigger on the eko that I found. For those who don't know I currently have a owb that I have been heating with for several years. At this time I just want to tie into my current plumbing setup as it works quite well and time is going to be a issue, I really don't want to have to re plumb everything on the house side. That said, please look at this diagram and let me know your thoughts. Everything on the diagram will be in a insulated outbuilding. The snag comes as I want a constant running pump at the underground lineset. I want this last tank to mix and cycle between 140-170. This is exactly how my owb cycles and it heats all my zones fine. What I don't want to do is mix my storage tanks. Thanks for any and all thoughts. This is all pressurized.

 

[pulse]

85 views and no comments. Did I say something wrong?

 

[ewdudley]

(Separator tank is "this tank".)

There would be little point in running the separator-tank-to-house-loop-circulator constantly. Normally only need to run when there is a call for heat. (If you want to get fancy you can use an aquastat on the return side of the water-to-air HX that disables the furnace fan until the coil is hot.)

Zone valve is not needed.

1.25" pipe feeding separator tank is likely much bigger than it needs to be.

Controlling storage-to-separator-circulator with an aquastat near the center of the separator tank, or lower, should work well. The range can probably be much tighter than 140-170. I think something like 140-141 would do the trick, maybe higher setpoint but still a tight range in the dead of winter.

 

[pulse]

(Separator tank is "this tank".)

There would be little point in running the separator-tank-to-house-loop-circulator constantly. Normally only need to run when there is a call for heat. (If you want to get fancy you can use an aquastat on the return side of the water-to-air HX that disables the furnace fan until the coil is hot.)

Zone valve is not needed.

1.25" pipe feeding separator tank is likely much bigger than it needs to be.

Controlling storage-to-separator-circulator with an aquastat near the center of the separator tank, or lower, should work well. The range can probably be much tighter than 140-170. I think something like 140-141 would do the trick, maybe higher setpoint but still a tight range in the dead of winter.

Thanks for your comments. Let me explain why I want constant circulation between the seperator tank and house. All hx's in my house are set up in a series, I wouldn't do it like this again, but for now it works. First is a plate exchanger for dhw, then to water to air hx in forced air furnace, then water to air hx in garage. I keep my house warm, 71 at night 74 the rest of the time. During winter one of the exchangers is almost always calling for heat. In winter I like a hot exchanger in the basement, warm floors just help make the house so much more comfortable.

How would the boiler charge storage without the zone valve? As far as pipe size, I always thought bigger was better.

 

[maple1]

If there is more head on the storage-house circuit, than boiler-storage circuit (say, smaller piping, more fittings, plus all the hx's), then the water should go the path of least resistance when the boiler circ is running. Orienting the T's so the straight shot is between the boiler & storage & direct to storage would also help. Along with having it be uphill from boiler right into storage. Maybe combined with having some downhill from storage to house. Imagine with no pumps & designing for convection between the boiler & storage.

Constant flow can defeat storage - good stratification optimizes storage capabilities. May be worth it to do manifolds in the house so you can parallel your loads & pump on demand.

Finer details also sometimes get lost in 2d drawings. Are those storage tanks stacked or side by side? The pipe going into the top one should be at the end opposite the one leaving it at the bottom. Also thinking the ins & outs of the separator tank should be at top & bottom - no direct experience with separators though. Also not sure how much benefit it would be in this application - usually they are used for multiple loads with varying temp requirements. And/or supplies with varying supply temps (like incorporating solar). I think - again, no direct experience, someone can correct if wrong on that.

Do you know from having run your existing system how low your supply temps can be & still maintain house temps?

 

[pulse]

If there is more head on the storage-house circuit, than boiler-storage circuit (say, smaller piping, more fittings, plus all the hx's), then the water should go the path of least resistance when the boiler circ is running. Orienting the T's so the straight shot is between the boiler & storage & direct to storage would also help. Along with having it be uphill from boiler right into storage. Maybe combined with having some downhill from storage to house. Imagine with no pumps & designing for convection between the boiler & storage.

Constant flow can defeat storage - good stratification optimizes storage capabilities. May be worth it to do manifolds in the house so you can parallel your loads & pump on demand.

Finer details also sometimes get lost in 2d drawings. Are those storage tanks stacked or side by side? The pipe going into the top one should be at the end opposite the one leaving it at the bottom. Also thinking the ins & outs of the separator tank should be at top & bottom - no direct experience with separators though. Also not sure how much benefit it would be in this application - usually they are used for multiple loads with varying temp requirements. And/or supplies with varying supply temps (like incorporating solar). I think - again, no direct experience, someone can correct if wrong on that.

Do you know from having run your existing system how low your supply temps can be & still maintain house temps?

I understand constant flow hurts storage, which is the reason for the separator tank. That tank will be around 150 gallons and I do not consider it storage, I want that tank to mix. In my mind the separator tank/house circuit is 1 large zone.

Forgive the drawing it is mostly a copy of Nofossils simplest pressurized storage with the addition of the separator circuit. Many details were left out as far as storage size, orientation, valves, air separators ect. The orientation of the tanks is still unknown. Storage will either be a single 1000 gallon tank or 2 500's hoping to set them vertical. I would prefer them vertical not sure if all the extra work would be worth it vs a single 1000 horizontal.

During the coldest part of winter I can heat with 140 water. I can maintain all the way down to 100-110.

 

[Tennman]

You didn't say anything wrong, just end of burn season doldrums. About 1-2 months ago there was a thread about supplying the demand loop off a big manifold on top of storage somewhat like you have drawn. Definitely on that discussion the demand pump was cycled on and off. On our system the size of the boiler-to-storage circulator is smaller than the storage-to-house pump. I installed a Laddomat loading unit (I think ~1/6 HP) on BioMass which is may be slightly more expensive than pump, Danfoss, and controls but it is an all-in-one solution and works perfectly for managing charging storage. We have Taco 0013 (I think ~1/3 HP) circulating between storage and the WTA HX in the house. The 0013 was sized to handle our btu demands and based on the water delta T coming out of the HX of a consistent 30*F, the 0013 and HX are ideally matched. So when burning, the smaller storage pump runs continuously until burn is done. Per your diagram, you want your bigger HX pump to run continuously which per your sketch is in series with the storage pump. So with the big pump running all the time how will your hottest water from the boiler ever get into the storage tanks? Lots of ways to control that demand pump. If your fan runs often, then your pipes under the house will still stay warm. Ours does. I chose to use two RIB relay products to turn our demand pump on/off based on the fan on/off. As Maple mentioned above, circulating continuously will dilute your storage. I've attached the schematic I used for our forced air system. Also the mixing tank will waste precious hot water. Bottomline, I think you design has lots of problems. After I hit Reply, I'll see if the PDF schematic is readable. If not I'll scan and upload as a .jpg. I highly recommend the plug and play loading units. We have a Laddomat and Calleffi. Both have worked perfectly. Hopefully this will stir the discussion from the experts here for you. I'm sure you'd find running your pump continuously is unnecessary and very wasteful. Best wishes.

 

[leon]

85 views and no comments. Did I say something wrong?

Nope, you did not say anything wrong. You have been given excellent direction with
regard to your inquiry.

You need to keep it simple to make it operate simply which means "Heat Rises".
and gallon of water is only capable of carrying only so many BTU per gallon

Before you drive yourself crazy with this and any possible plumbing combination
which will number in the thousands you want to make this as simple as possible.
you also want to take advantage of the fact that heat rises, hot water does not
"unless it is pumped". The less plumbing you have the fewer leaks your going
to have the less total head you will have and the less resistance.

Every piece of plumbing that controls heat and delivers heat is a "plumbing appliance"
every appliance has an effect on total head and head pressure.

I would like you to invest in a 2 paperback books "Pumping Away" and "Classic Hydronics"
written by by Dan Holohan. He writes his books for the layman and plumber alike and makes
his writing easy to understand and fun to read with many many actual examples he has
encountered and corrected many plumbing mistakes made by plumbers and home owners alike
in many years of being in heating business where he preaches simplicity in design and how to
control central heating and cooling systems.

He provides the reader with his real world examples that he has encountered over his many years
of being plumbers helper, plumbing supply house sales representative and plumbing and heating
troubleshooter in New York City and on Long Island.

He corrects many misunderstandings in piping and plumbing and shows the reader the simplest way to
handle plumbing issues with regard to heating and hot water and he has written extensively about
steam heat as well.

I would also suggest that you visit the forum he and his daughter own and manage which is Heating
Help where many of your questions will have been posted and answered as well.



Disclaimer: I have no affiliation financial or otherwise with Dan Holohan.

 

[maple1]

I understand constant flow hurts storage, which is the reason for the separator tank. That tank will be around 150 gallons and I do not consider it storage, I want that tank to mix. In my mind the separator tank/house circuit is 1 large zone.

Forgive the drawing it is mostly a copy of Nofossils simplest pressurized storage with the addition of the separator circuit. Many details were left out as far as storage size, orientation, valves, air separators ect. The orientation of the tanks is still unknown. Storage will either be a single 1000 gallon tank or 2 500's hoping to set them vertical. I would prefer them vertical not sure if all the extra work would be worth it vs a single 1000 horizontal.

During the coldest part of winter I can heat with 140 water. I can maintain all the way down to 100-110.

I'm not sure that mixing tank will benefit. I think the net effect will still be the same on storage, and you would actually be lowering your supply temps to the house. Which is also why I asked about knowing what you need for supply temps or not. But as I said, I have no direct experience with a separator tank.

 

[ewdudley]

How would the boiler charge storage without the zone valve?

I wasn't studying your diagram closely enough. To eliminate the zone valve, need to move connection point for the separator supply line pretty close to the top of storage.

If I remember correctly there is a design in the "Biomass-Hydronics-Training PDF" in the sticky threads that shows a design that uses gravity to feed a separator tank.

 

[ewdudley]

As far as pipe size, I always thought bigger was better.

Then hire a steamfitter to weld in some 4" or bigger, just to be sure.

 

[pulse]

So with the big pump running all the time how will your hottest water from the boiler ever get into the storage tanks?

Its very hard to explain myself when I don't know the correct vocabulary. My diagram doesn't show it well but the circulator (call it circ 3) that would run constant is between the seperator tank and the house. So I thought when the seperator tank aquastat hit high set point it would close the zone valve and turn off circulator (circ 2) on top of the diagram. Then hot water from the boiler would be forced to storage as the boiler circulator (circ 1)would run during firing.

 

[Tennman]

Ok... now I know what that circle is after the separator tank. We don't have two water-to-air (WTA) HXs, but otherwise we're doing today what you want to do but with just two pumps. I've read of some people having a buffer tank in the house that stores hot water from the last time the pump was turned on. Returning the cold water back to storage and turning that separator tank into a hot buffer (just hot in and out) I think would be better for preserving the btus you've put into all your water. The purpose of a buffer tank is to reduce the time it takes to get the hottest water into the WTA HX. On our system, when the fan first comes on, the air feels like heat pump temp. Takes about 10-15 seconds to get up to full temp from the hottest water from either underground or storage. Certainly not enough nuisance for me to add a buffer near the HX in the house. Our HX is roughly 200' from the storage.

I'd have the cold return to storage and delete the pump between storage and what you currently call the separator. If you don't mind the noise then putting the pump that feeds the HX's (circ 3) in the house near the furnace makes controlling by the furnace fan much simpler. I'd link the pump to furnace fan on. If for whatever reason you don't like it, you can then go to always on. But, the pump always being on is unnecessary and wasteful. That's a fact.

The room above where our furnace and HX lives always stays nice a warm without a buffer and turning the circ pump on only when the fan turns on.

Did you use a radiant heat schematic as your starting point? This approach seems overly complex to me and moving water all the time takes wood and electric energy. I'll just watch to see where this goes.

Don't worry about the right words. Most folks including myself came to this site totally green also. Most of us have been where you are. Cheers

 

[pulse]

I'd have the cold return to storage and delete the pump between storage and what you currently call the separator.

If I deleted that pump (circ 2) how would I draw off storage?
Circulator 1 would only be on when the boiler is firing.

 

[pulse]

I would like you to invest in a 2 paperback books "Pumping Away" and "Classic Hydronics"
written by by Dan Holohan. He writes his books for the layman and plumber alike and makes
his writing easy to understand and fun to read with many many actual examples he has
encountered and corrected many plumbing mistakes made by plumbers and home owners alike
in many years of being in heating business where he preaches simplicity in design and how to
control central heating and cooling systems.

I will order these books. Thanks

 

[pulse]

If I remember correctly there is a design in the "Biomass-Hydronics-Training PDF" in the sticky threads that shows a design that uses gravity to feed a separator tank.

I will look into this. Thanks

 

[pulse]

I'm not sure that mixing tank will benefit.

This was the only way I could come up with that would allow me to run circ 3 constant and not mix the storage.

 

[maple1]

I am thinking that if circ 3 runs constant, then circ 2 will be also. Or very nearly so.

 

[pulse]

I am thinking that if circ 3 runs constant, then circ 2 will be also. Or very nearly so.

Circ 2 would cycle on and off via the aquastat in the seperator tank which is why it would be set with a large differential.

 

[pulse]

Maybe I need to ask my question a different way. How do I get good stratification in my storage tanks when I have a house that is going to require a circulator to be running 85% of the time?

 

[maple1]

Tank verticallity?

Low flow rates on the load circuit also help.

A good deal of this depends on the characteristics of the house stuff, which we don't know much about. Are you sure on how much flow you will be needing to the house? Amount of time it is running doesn't really mean much without correlating with GPM. And delta T. Do you know how many GPM you're pumping while maintaining temps now?Might also be worth investigating upsizing your HXs. Maybe even adding some hydronic rads if you have places you could do it easily. If you can lower the flow needed and widen the dT through the house, the situation would improve.

 

[Tennman]

Here's our basic system which is working very well. Many do horizontal tanks, I was fortunate enough to do vertical. There have been some here that had the storage to HX loop off the top like your schematic, but it's not as common here. I personally like the idea of having a slug of thermal mass at the very top that is hottest to help modulate water temp for the HX supply line flow.

So boiler water enters at very top and boiler return from very bottom (best). We don't have the 3-way motorized mixing valve, we just pump from storage to HX and back. That's my 2 cents on your schematic. I hope you see the difference in how you have your circ 1 and 2 plumbed in series. You could keep your separator in the hot supply line as a buffer I mentioned above, but if your fan runs as much as you say, probably little value.

If you must heat the house to 74F and the fans running all the time, I suggest you go back and get a handle on what is the real heat load. Could be your old OWB was not able to keep up with the demand to supply consistent 140-170F water. The discussion started asking questions about schematics, but it doesn't appear you really understand how big a boiler you need or if the HX is properly sized. I can say that our home is most likely less efficient than yours and our fan or pump doesn't run all the time. You really need to understand why is the fan on all the time. I'm starting to think you're OWB and then your EKO might be undersized, but no way of telling. Gotta go make money.

 

[pulse]

View attachment 177989

So boiler water enters at very top and boiler return from very bottom (best). We don't have the 3-way motorized mixing valve, we just pump from storage to HX and back. That's my 2 cents on your schematic. I hope you see the difference in how you have your circ 1 and 2 plumbed in series. You could keep your separator in the hot supply line as a buffer I mentioned above, but if your fan runs as much as you say, probably little value.

If you must heat the house to 74F and the fans running all the time, I suggest you go back and get a handle on what is the real heat load. Could be your old OWB was not able to keep up with the demand to supply consistent 140-170F water. The discussion started asking questions about schematics, but it doesn't appear you really understand how big a boiler you need or if the HX is properly sized. I can say that our home is most likely less efficient than yours and our fan or pump doesn't run all the time. You really need to understand why is the fan on all the time. I'm starting to think you're OWB and then your EKO might be undersized, but no way of telling. Gotta go make money.[/QUOTE]


So you don't have a circulator between the boiler and storage? If so I don't see it on the diagram. Its not that the main furnace fan runs all the time probably more like 50% of the time once house is up to temp from set back. We are a family of 5 so we use A LOT of hot water, then there is the garage hx. So many times one or two of the hx's is making heat. As far as sizing I think I am pretty close the delta t of the main furnace hx is 25. The plate water hx is 15. and the garage hx is 15. I honestly do't know the flow but I would guess close to 4gpm. The owb is at capacity during cold snap but was always able to cycle between 140-170. The eko that I am going to buy is a 60.

I have revised my diagram based on all the input I have got from everyone. Thanks to everybody for your patience with me and all the good free advice. I think I am getting closer to a good design from all of it. I still want the ability to pump constant from the separator tank to the house, but I think I could try the demand style even with this setup and see how it goes.

 

[pulse]

Tank verticallity?

Low flow rates on the load circuit also help.

A good deal of this depends on the characteristics of the house stuff, which we don't know much about. Are you sure on how much flow you will be needing to the house? Amount of time it is running doesn't really mean much without correlating with GPM. And delta T. Do you know how many GPM you're pumping while maintaining temps now?Might also be worth investigating upsizing your HXs. Maybe even adding some hydronic rads if you have places you could do it easily. If you can lower the flow needed and widen the dT through the house, the situation would improve.

Im not really sure on the flow but I would guess around 4gpm. DT for the main furnace is 25, 15 for the plate hx, and 15 for the garage.

 

[Tennman]

We use a loading unit between our boiler and storage. A loading unit combines all the pieces necessary for managing boiler to storage flow in one device. That's what's shown in the schematic above sitting down beside the boiler. Google Laddomat loading unit. Many do the same thing with multiple components. Pictures help me. Below is our BioMass setup. You need at least 10' of ceiling height for 500 gal propane tanks.