cold pipes in boiler room, help?

[user]

Hi all, my home uses a natural gas water boiler for radiant floor heating and I've been having a problem with low temperatures in the pipes. Sometimes it gets hot again after I try to drain air bubbles out of the pipes, but the problem keeps coming back.

There are two pumps (circulators) for the hot water going out of the boiler. The boiler is running fairly hot (about 140F as intended) and the water going through the first pump is also hot to the touch, but the water going through the second pump is not hot. The thermometer attached to the pipe out of the second pump reads 80F now, which is about 60F lower than the boiler's temperature after about 3 feet of piping -- I assume this is not normal, right?

I believe that the second pump was installed incorrectly by a family member because the manual says "Only install the pump with the motor shaft horizontal", but the shaft is vertical in our installation:
http://documentlibrary.xylemappliedwater.com/wp-content/blogs.dir/22/files/2012/07/P86203F.pdf

This video says the same as the above:
[ame]https://www.youtube.com/watch?v=UvrR5ZAkf10&feature=youtu.be&t=1m20s[/ame]

The following suggests that such orientation causes air bubbles to be trapped in the motor, which seems to fit with my symptoms:
[ame]https://www.youtube.com/watch?v=yiMECpYRByI&feature=youtu.be&t=2m17s[/ame]

I suspect trapped air in the pump is causing a lack of circulation, and the boiler may be getting turned on constantly which doesn't help -- this month my bill is 3 times more than last December (lol).

I am inclined to get a pump with the correct orientation or ask a plumber to cut the pipes and turn the pump flanges by 90 degrees. If I should get a new pump, I'm not sure how much GPM I need, but I suppose a stronger one is safer. Do you have some different suggestions? Sorry I don't know much but would appreciate some tips!

 

[Mr_David]

What size of line is the pump on. bigger is not always better.
Is the pipe the pump is on horizontal, like in the video or vertical?
you need a hose bib on the line and maybe some isolation valves so you can efficiently bleed the air out.

 

[Matt30]

Loosen one side of the circulator bolts a little bit and see if you get hissing/bubbling . Sounds like it's air locking there.

 

[Mr_David]

post some pictures. maybe the 2nd pump is backwards.
pump does not push the water. They cup the water and just move it along. If it gets air in the pump and that air can not migrate out on it's own, then the pump cannot cup the water to move it along.

 

[frodo]

have you checked the zone valves for proper operation ?

the T stat tells the valve to open or close when the room calls for heat

should look like this

 

[user]

What size of line is the pump on. bigger is not always better.
Is the pipe the pump is on horizontal, like in the video or vertical?
you need a hose bib on the line and maybe some isolation valves so you can efficiently bleed the air out.

The surrounding pipe is about 35mm or ~1.4" in diameter.
The pipe is horizontal, but the pump motor is vertical (which I have not seen in any plumbing picture or video online so far)

I have tried to bleed the system a few times. Today I bled each zone and the water appeared clear and air-free.

 

[user]

Loosen one side of the circulator bolts a little bit and see if you get hissing/bubbling . Sounds like it's air locking there.

I tried to do this until it started leaking but I did not hear much difference in noise. The nearby functional (hot) pump made more noise, which might be water.

 

[user]

post some pictures. maybe the 2nd pump is backwards.
pump does not push the water. They cup the water and just move it along. If it gets air in the pump and that air can not migrate out on it's own, then the pump cannot cup the water to move it along.

I'll try posting a pic later. The 2nd pump is pointing away from the boiler. If it was the wrong direction, I think it should never have worked, but my low temperatures had been an intermittent problem for a couple years.

I took the pump apart earlier and plugged it into a household outlet. It does spin, but I don't know whether it's working well when mounted.

 

[user]

have you checked the zone valves for proper operation ?

the T stat tells the valve to open or close when the room calls for heat

should look like this

Edit: after bleeding the system thoroughly and manually opening the zone valves, I just saw >100F temperature for the first time in a few days. I'll see whether the temperature gets higher still. Thanks for the reminder in any case.

 

[frodo]

if the one valve did not operate,


if your valves are low volatage, check the transformer for operation