Hydronic heat, new for me, one zone suddenly stopped working

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Old 01-04-13, 09:50 AM
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Hydronic heat, new for me, one zone suddenly stopped working

Moved into house 1 year ago with boiler heat. Just this week as temperatures dropped well below freezing (coincidence?) one of the zones stopped working. I checked the zone valve, the motor works and I can also turn the valve by hand once I remove the motor, so I think that it is not the problem. I finished the basement this year, so could be a frozen pipe....Also saw some posts here that indicated that it could be an air-lock. However, with the layout of my boiler plumbing I am not sure how to force water through the bad zone. There is only one drain tap attached and it is between the boiler and the circ pump which pumps away from the boiler (ie it is on the hot side). So if I close the other zone valves and then open the drain, water coming out could just be from the pressure in the boiler (or the valve the adds water from the street line in to maintain pressure), and not water moving through the bad zone. Picture attached. I'd like to be able to confirm that I do not have a blocked pipe (frozen) but not sure this layout will allow me to do that.

On a side note, the pressure seems to run from 21 to 27 psi, is that high?
 
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Old 01-04-13, 10:04 AM
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Let's see the return piping also, in addition to the water feed/fill setup to the boiler.


I finished the basement this year, so could be a frozen pipe....
Why would finishing the basement cause a frozen pipe?
 
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Old 01-04-13, 10:14 AM
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If your pressure gauge is even accurate... yes, 21-27 is a bit on the high side.

There are two 'sticky' posts at the top of the forum list...

One about "Verify your pressure gauge" and another about "Relief Valve Leaking..."

You need to read through them both.

Let me get a bit more clarification on the exact problem first...


When the basement zone calls for heat, you say that the zone valve opens, yes?

What happens AFTER that?

Does the circ pump run? Does the boiler fire?

If the boiler simply does not respond to the zone valve opening, then the problem IS in the zone valve, with the ENDSWITCH to be exact.

So, if the boiler simply does not respond and you want to prove that it's not a frozen pipe, do this:

Push the thermostat on the bad zone all the way up to call for heat constantly.

Now go to one of the OTHER zones and push that thermostat up a few degrees.

Since the 'bad' zone valve is OPEN, when the pump starts for the OTHER zone it will also push water through the bad zone... does it?
 
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