Hot water heating system pressure

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DIYorBust

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I think they were going for something like this which is similar. The boiler pump dust pump into the boiler and it appears that's recommended by navien.

1645599567416.png
 

John Gayewski

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OK, I'll finally got the picture resized and here it is.

The house is a 4-story rowhouse with the boiler in the cellar, so yes it's approximately 40' and this is consistent with the plans and surveys and a reasonable visual inspection. Now I would say a PSIG of -2 is not okay based on experience, because the radiators become airbound. This is not a calculation, but an observation. With the pressure it 22 cold at the boiler, the top floor radiators stay hot. I'm not sure if the minimum needed is 20, but it's not 17, at 17 the radiators fill with air. I'd say a pressure of 22(cold at the boiler) keeps the radiators hot, it's hard to test exactly, in part because I have to climb 5 stories to observe conditions at the top.

Do you think it would work to simply turn the primary loop pump upside down and pump away from the boiler?
Edit: I see this would not work. Could I move it to the flow side and pump away? Any other options?

To be clear, I did not do the install or choose the pump locations, it was a professional install by a licensed plumber who is an authorized navien dealer and has done many installs including commercial jobs like small hotels etc. However my guess is those have the piping spec'd by an engineer. In fact I requested a different configuration, but he said this would pass inspection and everything is fine.




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Is it possible for you to know how many feet of pipe you have and the sizes? Or do you by chance know how much water is in the system when full?
 

DIYorBust

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Is it possible for you to know how many feet of pipe you have and the sizes? Or do you by chance know how much water is in the system when full?
It would be a guess, but maybe 240 feet 1.25 inch risers and then maybe another 50-100 feet of branches, plus four 15 foot fin tubes and 6 steel radiators.
 

John Gayewski

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It would be a guess, but maybe 240 feet 1.25 inch risers and then maybe another 50-100 feet of branches, plus four 15 foot fin tubes and 6 steel radiators.
Looking at your picture I can't see where the expansion tank is hooked into the system. Where is that?
 

DIYorBust

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It connects after that sensor well on the lower right of the picture. And there are two tanks there, an ex60 and an ex30(not seen in picture).
 

Fitter30

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Don't like how the system is piped. Dirt magnet should be before the boiler not afterwards not tring to protect the heat emitters but the boiler heat exchanger and the small passages. That sensor in expansion tank piping is take the fill line also? If it is that water isn't seeing true system temp water really doesn't move much. Spirovent probably needs to be take apart and cleaned the screens in it are probably dirty because its before the dirt magnet and should be piped where the dirt magnet i because the water is hotter. Expansion tanks piped into the bottom of the spirovent with fill line..
 

DIYorBust

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Don't like how the system is piped. Dirt magnet should be before the boiler not afterwards not tring to protect the heat emitters but the boiler heat exchanger and the small passages. That sensor in expansion tank piping is take the fill line also? If it is that water isn't seeing true system temp water really doesn't move much. Spirovent probably needs to be take apart and cleaned the screens in it are probably dirty because its before the dirt magnet and should be piped where the dirt magnet i because the water is hotter. Expansion tanks piped into the bottom of the spirovent with fill line..
I think the pumps are all pumping up, so the dirt mag is just before the return enters the boiler/primary loop. The dirt mag was installed at my request because I asked for an ecm circulator pump and didn't want the magnet to get fouled.
 

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This guy simply needs to run with less pressure. Air doesn't make its way into a system unless the system is pulling a vacuum. His comments about lower pressure creating air doesn't hold up. Fill with more pressure bypass the boiler or plug the relief if necessary circulate to run the air out. Then drop the pressure and run the boiler at.
 

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It's an nhb 150, Navien. What pressure would you have me run it at? It take 17 to fill the system by the book, but realistically that won't fill the top floor. It just doesn't work, it takes around 21-22psi to bleed the system and get it going. If I bleed it and then drop the pressure eventually the top radiators get cold and I have to do it again. This is not a theory at all, its just what happens. Are you saying that the system needs to tolerate a pressure increase of 10 psi?
 

DIYorBust

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This guy simply needs to run with less pressure. Air doesn't make its way into a system unless the system is pulling a vacuum. His comments about lower pressure creating air doesn't hold up. Fill with more pressure bypass the boiler or plug the relief if necessary circulate to run the air out. Then drop the pressure and run the boiler at.
I said air get sucked in if the pressure is less than the atmospheric pressure, not in general. But if the pressure is very close to atmospheric at the top, air seems to get stuck there.
 
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