Radiant heat pump size

[leiterch]

So I fired up my heating system yesterday and I think I got some bad advise from the local heating supply store. I haven't went out and checked this morning, but I don't think I have enough water volume and now I could really use some guidance as I'm afraid I'll be freezing the slab and I think my problem is affecting my house system.

Here is the setup.

Outdoor wood boiler with two Bell and Gousett NRF-22 pumps located on the boiler independently controlled.
1 pump runs to the house about 100' through 1" pex into a water to water exchanger and back to the stove. Never had an issue with this setup for about 7 years. This is a constant pump circulation setup.

The other pump was purchased when the stove was new for an additional pole barn. The barn setup is as follows. 1" pex about 100' to the pole barn hooked directly to a 6 zone manifold each run is about 240' of 1/2" pex then returned back to the outdoor wood stove.

Both pumps share a return at the wood stove.

I don't have confidence that I'm getting proper flow back to the stove and it seems to be affecting the house loop. I believe that I need to put a pump in the pole barn. The real problem I have is I don't know if I should upgrade the pump on the stove and add a pump on the return side after the manifold.

I'm hoping there are some pumping guys on here that can lead me in the right direction.

Oh, the pole barn pump is being controlled with a pump controller off a thermostat. I ran 110 from the barn back to the wood stove when buying the pex.




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[brewchief]

Why do you think you have a problem?
Can you post some pics of your setup?

 

[leiterch]

I

Here is my setup.

Yesterday I saw the incoming water as high as 120*, but the return side hasn't gotten above 40*.

I did the calculation again and the pump should be good. My calculations give me 6.6gpm at 12' of head. That is using the add 2 method.

I think it must be air. I've purge each zone out. The weird thing is how the house system is acting. I think because of the shared return lines at the wood stove the air in the barn is affecting the house also.


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[dfiler2]

You may still have air but it can take many days to warm up a floor I would say the problem with the house is because you have your supply's at the bottom of the furnace. The cold water being returned to the system is heavier that the warm water and is falling to the bottom as soon as it is returned. You always pull the supply from the high point where the warmest water is. Try restricting the flow to the floor by shutting off some of the loops and see if the return water warms up, which will in turn give you warmer water for the home. Then warm the floor slowly by turning on more loops a little at a time.

I have worked for an outdoor boiler company for over 20 years and have seen manufactures mark the bottom ports as the supply many times, this is backwards. It may work if the heat load is small enough but not the correct way to do it. Do you ever have problems with boiling the furnace?

 

[leiterch]

I don't have issues boiling the stove. You comments make total sense. I think Air is the culprit. I'm going to try and bleed the system again and see what happens. I did the calculations again and the pump I have on the stove should have no issue.
Do you think since the stove and the barn share the return that I might be getting some back feed from the house to the barn on the return side? This could make the house use operate strange until all the air is out of the system.


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[dfiler2]

I really don't think the returns mixing are an issue, assuming the flow on both loops is the same, the problem is that the cold return water is falling to the bottom of the boiler and then being circulated back to the buildings.

And I agree, your pumps are fine.

 

[leiterch]

Ok, I tried to bleed again. I shut off the return at the pole barn to the stove. I then went zone by zone purging the air. I then turned all the zones on and no air bubbles in the bucket. I then slowly turned on the return side and I started getting air. I also saw the temp rise up on the return side as soon as I started opening the valve. I'm really at a loss here. I can't seem to get this thing flowing correctly.


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[anthony666]

if it were me i'd have put a heat exchanger in the barn too and run the floor closed loop

is that oxygen barrier heat pex in the floor ?? if it's regular plumbing pex you're always gonna have air issues .. at that point i'd install an air eliminator on the cold side in the barn just to try & stay on top of it, although ive seen the bottle brushes rot right out in just a couple of years if the system constantly is absorbing oxygen

for right now i'd do what dfiler suggests for now and shut down loops and let the floor cook up in stages .. and i fully agree on the hot water picks should be high in the boiler .. he works for central boiler and knows his business

also if you're seeing that kind of temp differential your pumps are doing their job and then some

 

[leiterch]

Thanks for the replies. I was thinking about an exchanger in the barn, but I don't have a water source in the barn for system loss. I am still leaning that way and just manage the barn water level.

It is oxygen barrier in the floor.

The two pumps aren't balanced. Since they share the same return. The house is only 200' of 1" pex through an exchanger. The barn is 250' of 1" pex and then 1500' of 1/2" pex for the barn.

Would there be any benefit to restricting the return at the stove of the barn side to stop some of the back feed? I think I might have to get someone out here to do some work. My problem is it is 7* and I really don't want stuff to freeze and I'm going out of town next weekend and I don't want to leave my wife with a headache.


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[leiterch]

So I tried something tonight to see what might be happening and now I'm more confused than ever.

I turned off my return at the stove and shut down the pump for the barn, thus making one huge loop.

It starts at the pump on the stove through 100' of 1" pex to a water to water exchanger then through another 100' of 1" pex back to the return at the stove, with the return inlet shut, the water would then go through 125' of pex to the return side of a 6 zone manifold with each zone containing around 240' of 1/2" oxygen barrier pex then it would travel back through the supply side to the stove through 125' of 1" pex. As soon as I did this the temps on the return side of my manifold jumped up and the supply side went way down. Problem is the delta is 100*, I don't think that is normal.

I'm pretty perplexed at the whole situation. If you guys know anyone in the Northern Michigan area that could help, I think it's time for professional help and not a shrink, I'm way past that.


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[mygarageone]

Is you shop / barn higher than your outdoor boiler ?

 

[brewchief]

What do you have for insulation under the slab? How thick is the slab?

Are you getting any heat in the barn from the slab? It may take a couple of days to bring the slab up to temp.

 

[leiterch]

Barn is lower.

2" foam under and around the perimeter of the slab.


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[dfiler2]

So I tried something tonight to see what might be happening and now I'm more confused than ever.

I turned off my return at the stove and shut down the pump for the barn, thus making one huge loop.

It starts at the pump on the stove through 100' of 1" pex to a water to water exchanger then through another 100' of 1" pex back to the return at the stove, with the return inlet shut, the water would then go through 125' of pex to the return side of a 6 zone manifold with each zone containing around 240' of 1/2" oxygen barrier pex then it would travel back through the supply side to the stove through 125' of 1" pex. As soon as I did this the temps on the return side of my manifold jumped up and the supply side went way down. Problem is the delta is 100*, I don't think that is normal.

I'm pretty perplexed at the whole situation. If you guys know anyone in the Northern Michigan area that could help, I think it's time for professional help and not a shrink, I'm way past that.


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Not really sure what you are saying here, but if you shut the "return inlet" the water won't be going anywhere. Ok, just look at the pics again and I get what you are saying, the temps would make sense because you are now pushing the water backwards through the loop. Have you tried what anthony666 and I have suggested?

 

[MagKarl]

I'm going to suggest you take the time to draw an accurate diagram of your setup, and include a picture of each point of interest on that diagram.

 

[leiterch]

So I've had a couple days. I have one thing figured out. There is something going on with the pump and balance. I isolated the barn floor from the stove and had the main 1" line loop back and everything works as it should.
I am going to go down the path of separating the barn from the stove. As of right now, I know that works. It makes more sense and a more robust system. I blew the lines out in the barn so I wouldn't have any freezing issues.


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[anthony666]

the bit that bugs me about your system is the return to the boiler .. both streams have to collide and merge and make a 90 at the same time .. that is a major bottle neck .. since you have things took apart anyway, try this;

take the return tee off the boiler, replace it with a 90 .. bring about a 10" ****** vertically, then a tee, continue vertically with a 6" ******, then another 90 .. what you're gonna end up with is in the shape of a capital F .. join up the returns to the horizontals on the F this .. this will stagger the streams and give them a bit of room to merge before they head home .. that should take care of that bottle neck

then to repeat what i said before, heat exchanger in the barn, run that closed loop

if things go south and you leave the tubes in the barn wet, pour some full strength rv antifreeze into the lines, the red thin stuff .. just flush it later before you connect it back up

also female/female 90's and ******* are better than those elbows that need the bushings ..its the same number of threaded joints and there's no internal restriction .. think of water flow like traffic on the highway .. any time you go from three lanes down to two you get major slow down, try to avoid that when ever possible

 

[mygarageone]

Have you observed the flow meters to determine if you have flow ? Ya I know stupid question. But one of the things I do, is make sure I have flow threw each loop,one at a time. Are you absolutely sure your pumps is working , have you tryed the by pass valve to prove flow ? Shut the manifold valves off open the bypass valve and you should have return pipe temp rise rapidly . If not , there's a flow issue ?

 

[theoldwizard1]

I don't have confidence that I'm getting proper flow back to the stove and it seems to be affecting the house loop.

Put a check valve on each return line at the stove.

 

[anthony666]

Put a check valve on each return line at the stove.

i think that will just exacerbate the problem .. a check valve is a huge head loss for an impeller pump

i don't use armstrongs everyday, but there's a good chance they come with a checkvalve in them from the manufacturer anyway

 

[mygarageone]

I once had a house lower than the boiler , I had a hell of a time eliminating air from the system. I did'nt do the piping the home owner did and I had for several hrs of my getting his system going , no dam air vents or purgers.
Circulators won't move water past an air block and both your circulations are at the unit.

 

[mygarageone]

i think that will just exacerbate the problem .. a check valve is a huge head loss for an impeller pump

i don't use armstrongs everyday, but there's a good chance they come with a checkvalve in them from the manufacturer anyway

Most do now days .