Shower is turning on heat

[moreira85]

I have 2 zones for baseboard heating, 1 down stairs and another upstairs. Also one zone for A/C. when the kids take long showers upstairs in zone 2 and I have the A/C running (heat is turned off) this will trigger baseboard heat to come on. even though it says thermostat is calling for A/C. usually when this happens I pull the nest thermostat off the wall until they get out of the shower and this will turn off the heat.

‘does this sound more like a thermostat issue or problem w a Taco zone valve maybe ? I noticed while they are taking a long shower the boiler will kick on and the hot water will flow through the zone valve which is open and up through the radiators even though the thermostat is not calling for heat.

TRYING TO ADD PHOTOS BUT IT SAYS THE FILES ARE TOO BIG

 

[moreira85]

 

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[John Gayewski]

Your zone valve is stuck open. Try turning the heat on and the thermostat up to make the zone valve call for heat then shut it back off. See if you can hear it open and close. If that doesn't work to get it closed you'll probably need a rebuild kit.

 

[moreira85]

Your zone valve is stuck open. Try turning the heat on and the thermostat up to make the zone valve call for heat then shut it back off. See if you can hear it open and close. If that doesn't work to get it closed you'll probably need a rebuild kit.

Thanks I will try that And try to trouble shoot. I have three zone valves though see photo. valve 1 comes from the indirect water tank boiler supoly. Valve 2 goes to the first floor (which does not have an issue with this zone when we shower. Valve 3 goes to the second floor this is the one that is stuck open I believe. I will replace the head but how do I know if it’s the 1st valve or 3rd valve with the problem?

 

[moreira85]

Thanks I will try that And try to trouble shoot. I have three zone valves though see photo. valve 1 comes from the indirect water tank boiler supoly. Valve 2 goes to the first floor (which does not have an issue with this zone when we shower. Valve 3 goes to the second floor this is the one that is stuck open I believe. I will replace the head but how do I know if it’s the 1st valve or 3rd valve with the problem?

I have 2 of the taco zone heads lying around. Not sure if they are good I can try swapping it out or pick up a new one.

 

[moreira85]

Why would removing the thermostat off the wall close the zone though?

 

[John Gayewski]

Why would removing the thermostat off the wall close the zone though?

Huh?

 

[moreira85]

Let me clarify. When the kids get in the shower this turns the heat on. If disconnect and I pull the nest thermostat off the wall the heat will turn off

 

[John Gayewski]

Let me clarify. When the kids get in the shower this turns the heat on. If disconnect and I pull the nest thermostat off the wall the heat will turn off

You need a multimeter. Nest thermosts don't work with hydronics. They are known bad products for that type of heat.

 

[moreira85]

You need a multimeter. Nest thermosts don't work with hydronics. They are known bad products for that type of heat.

 

[moreira85]

Do you think I should try a different thermostat? I feel like I’ve always had this issue since I’ve put the nest thermostats in. I can try replacing the taco zone head if that doesn’t work. I’ll try a different thermostat.

 

[John Gayewski]

Do you think I should try a different thermostat? I feel like I’ve always had this issue since I’ve put the nest thermostats in. I can try replacing the taco zone head if that doesn’t work. I’ll try a different thermostat.

If you have hydronic heat buy a thermostat that is made for hydronic heat. They have them that also I have cooling, but they are for boiler heating. Even guys that do only controls for a living appreciate a nice simple control.

 

[moreira85]

Replaced the zone head problem solved.

 

[moreira85]

Ugh I guess it’s not fixed my wife said heat came on when she took a bath today. My buddy said I need to switch To a new thermostat

 

[Mulon1982]

I have 2 zones for baseboard heating, 1 down stairs and another upstairs. Also one zone for A/C. when the kids take long showers upstairs in zone 2 and I have the A/C running (heat is turned off) this will trigger baseboard heat to come on. even though it says thermostat is calling for A/C. usually when this happens I pull the nest thermostat off the wall until they get out of the shower and this will turn off the heat.

‘does this sound more like a thermostat issue or problem w a Taco zone valve maybe ? I noticed while they are taking a long shower the boiler will kick on and the hot water will flow through the zone valve which is open and up through the radiators even though the thermostat is not calling for heat.

TRYING TO ADD PHOTOS BUT IT SAYS THE FILES ARE TOO BIG




Also, since we’re already dealing with heating and updating the upstairs space, I’ve been thinking about freshening up the walls too — maybe something more personal. I recently came across this pod wallpaper that lets you upload your own design or artwork, which could be a cool way to tie the space together once the HVAC issue is sorted.

That definitely sounds frustrating. From what you're describing — especially the fact that the baseboard heat kicks on even when the thermostat is calling for A/C — it could be a couple of things.

It could be the Nest thermostat sending a false signal, but the fact that pulling it off the wall immediately stops the heat makes me lean more toward an issue with a zone valve. If your Taco zone valve is stuck open or malfunctioning, it might be allowing hot water to flow even without an active heat call from the thermostat. Some zone valves can fail in an "open" state, especially older ones or those with weak return springs.

Also, during long hot showers, there might be enough residual heat or humidity to confuse the thermostat or trigger some odd behavior if wiring isn’t perfectly isolated between heat and A/C systems. Could be a wiring or control board issue too.

If you haven’t already, you might want to check:

• If the zone valve for upstairs (Zone 2) is physically warm or making noise when it shouldn’t be
• If the valve opens/closes properly when calling for heat vs. A/C
• Whether the end switch on the valve is triggering the boiler unnecessarily

Photos would definitely help, especially of the wiring at the thermostat and zone valves. If the forum won’t take large files, maybe try resizing them or uploading to an image-sharing service and posting the link.

Let us know what you find — it’s a weird one for sure.

 

[moreira85]

I will try to get photos. It’s two different systems. I don’t have a C wire going to the thermostat.