One zone won't heat up at times

bjohnrini

I have a 4 zone baseboard heating system. Occasionally, one of the zones won't heat up. When the thermostat kicks in, I can feel the circulator pump get hot, but not the pipe above that. I thought it was the circulator pump and had that replaced, but it hasn't helped much. The problem is not constant, but tends to happen randomly. Seems to happen more often when the thermostat has been lowered (overnight or after work hours) during which I tend to set the thermostat lower. I tried turning the flow control valve and it started to heat up. Is the problem with the flow control valve, or something else?

Appreciate any help
Thank You

Paul48

Do you hear air when you turn the flocheck (glub-glub)? Is there a means of automatically removing air from the system?

bjohnrini

I don't recall hearing any noises when I opened the flocheck. Only the noises of the pipes expanding. It does have an air expansion tank, not sure if that helps. Other than that, I don't know of automatically removing air from the system.

HomerJSmith

Since it is an occasional problem and the zone works normally some of the time, I would look at anything that may be restricting flow. The flo-check would be high priority, look see.

Next time it happens, while it is non performing and the pump is hot and the pipe above is cold, take a hammer and tap on the flo-check and see if that allows water to flow.

HomerJSmith

It is possible the the blk iron supply and discharge pipes from the taco pump may be corroded almost closed, restricting the flow.