Why won't one of my heating zones heat?
December 28, 2017 12:13 PM   Subscribe

We have four heating zones in our (new to us) house, using gas-powered baseboard heating. We've only just turned on the fourth zone today since temperatures have nosedived, and the baseboards won't turn on. Help me troubleshoot?

We have a gas furnace and four zones; the one in question is our finished basement. All other zones heat perfectly happily without us doing anything in particular. The thermostat is the same as others in the house and we've programmed it; according to it, it's got the heat turned on.

There's a photo of our furnace setup here. The pump closest to me is the one that feeds water into the basement zone (labelled "base"). The pipe feels hot; below the bleed valve I can't grasp it without it hurting, above it I can hold it for a short time before it gets uncomfortably hot. I've opened that valve and hot water comes out, no hissing air or anything. Following that pipe into where it disappears into the wall, it stays that same I-can-touch-it-but-not-for-super-long temperature.

The switch on the wall is labelled "base" and goes into the pump and into a wall switch that is on, as far as we can tell (all other switches to all other zones are similarly positioned when on). I have no idea what that red button on top does. This model has proven ungoogleable.

There are three baseboards in the basement. All are ice cold right now. None seem to have valves on their entry points, which the internet suggests is usually one of the things to check when you have this problem. I'm really quite at a loss as to what else to try before calling out a professional (as it's already down to 57 inside in the basement, and one wall is walk-out while the other is our unheated garage, I'm pretty keen to figure it out before temps start dipping below zero tonight). What else should I try?
posted by olinerd to Home & Garden (10 answers total)
Do you hear the basement pump working? You should be able to hear some kind of humming or something if it is going. If it is not humming/making noise, then it isn't running and may not have any power. Check the power to the pump - plugged in? Circuit breaker ok?

The red button looks to me like a "reset" button - maybe for some kind of breaker. I would try it unless others have better ideas.
posted by Mid at 12:19 PM on December 28, 2017

Recently in my apartment one zone stopped working. I called for service. They found that the problem was in the electrical device that acts as a faucet to turn the hot water flow to that zone on and off as dictated by the thermostat. It needed replacement, which only took a couple of minutes.
posted by jkent at 12:21 PM on December 28, 2017

Is it a programmable thermostat that controls this zone? If so, consider putting fresh batteries in it. Often, there's enough juice to run the display, but might not be enough to trigger the actual on/off cycle.
posted by cosmicbandito at 12:23 PM on December 28, 2017 [1 favorite]

Replaced the thermostat batteries. No change.

Pushed the red button. No change.

The pump is definitely running. If I switch the thermostat off and then on again, I can hear the solenoid in the pump control switch click on, and the pump itself starts to vibrate and hum.

What would cause it to pump hot water successfully into the zone’s feeder pipe but never let the hot water get to the pipes behind the baseboards?
posted by olinerd at 12:56 PM on December 28, 2017

Potentially the valve control as noted above. If that's what it is, it's a cheap part and easily replaced, you can look at the ones on your furnace and try to figure out which one it is and get a new part but I'd call a HVAC company out and have them do it because they will probably have the part in hand.
posted by fshgrl at 1:27 PM on December 28, 2017

Are the baseboards the kind where a panel at the front, over the radiating fins, swivels to turn the baseboards on and off? If so, to turn them on you kind of swivel the panel up to the top to expose the fins.
posted by leahwrenn at 2:19 PM on December 28, 2017

The pump for the basement zone might be seized (thus, humming when there's a call for heat in the zone, but the impeller isn't spinning and circulating water. ) Someone might have accidentally closed a shutoff valve somewhere in the loop for the zone. Your system does not appear to use electrically operated zone valves (instead it uses individual pumps for each zone.)
posted by Larry David Syndrome at 2:27 PM on December 28, 2017 [1 favorite]

Also, there appears to be a shutoff valve below the pump for the basement zone. Is it open? You will still get water out of the bleeder above the pump even if the valve below the pump is closed. (Water can take two different paths through the loop.)
posted by Larry David Syndrome at 2:36 PM on December 28, 2017

The pro has been and gone - it is indeed a pump problem so he’s replacing it tomorrow. Thanks for all your help in assisting in narrowing it down before I called in someone!
posted by olinerd at 3:23 PM on December 28, 2017

My guess is that it is the pump not functioning as it was intended.
posted by AugustWest at 6:48 PM on December 28, 2017

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