Two zones not working - baseboard


Old 10-12-20, 05:49 PM
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Two zones not working - baseboard

Before I continue I want to clarify that I am not sure if this is a "Steam and Hot Water Systems" issue or a "Thermostatic Controls" issue so I am just going to pose the question here.

Background on my system:

- I have a two story home
- I have a gas\boiler system
- I have a 4 zone series loop heating system
- Two of the zones are for the baseboard heaters downstairs
- Two of the zones are for the baseboard heaters upstairs
- The two zones downstairs are controlled by a thermostat located downstairs
- The two zones upstairs are controlled by a thermostat located upstairs

The problem:

The problem that I am having is that the thermostat that controls the two zones upstairs (zone3 and zone4) doesn't seem to work. What I mean by that is when I turn it on it doesn't make the clicking noise and the heat doesn't come on to those two zones therefor the baseboard heaters upstairs never get warm.

Troubleshooting steps I've taken that didn't fix the issue:

- I verified that the wires going into the thermostat were clean and seated properly.
- I used a multimeter and verified that the wires had 24vac coming to them.
- I replaced the upstairs (non working) thermostat with the downstairs (working) thermostat.
- I used the zone control valves for the working zones1 and 2 on the non working zones3 and 4.
- I verified that the wires going to the zone control valves were clean and seated properly.
- I bought a new thermostat.
- I reset the breaker for the system.

At this point I'm beginning to think it's a wiring issue somewhere in the box where the zone control valve lines come out of. I'm not sure what the name of that box but I think it's called a zone switching relay. It's mounted on the wall next to the boiler and it has 4 long wires coming out of it and each wire goes to a separate zone control valve.

In the mean time, the only way for me to get heat to the zones upstairs is to do the following:

1. Turn on the heat using the downstairs thermostat.
2. Once I hear the heat kick on I remove the two zone control valves for zones upstairs. When I do that I can hear water rushing through the pipes and the baseboard heaters upstairs start to heat up.

By the way, on my particular zone control valves there is no lever to put them into manual mode. I was able to google them and found that removing the zone control valves is how you put the system into manual mode.

Anyway, is there something that I am missing? Is there any other thing that any of you can recommend that I try before I call out an HVAC tech or an electrician?

Any tips or tricks would be greatly appreciated.

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Old 10-12-20, 06:18 PM
PJmax's Avatar
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Your thread here is good. You have questions/problems with the system.
Thermostat forum is mostly for upgrading to a new thermostat..... like a wifi thermostat.

We need model numbers and pictures. We love pictures.
Model number of zone valve and zone controller.
Take the cover off the zone controller.... post a picture.


Old 10-15-20, 03:03 AM
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If all your zone valves are the same i would label the one that you know works, and move that one onto one of the zones that does not work and see if that works. This is a surefire way to know if the problem likes with the zone valve. I have had my share of problems with zone valves myself. They seem to burn out every 5 years or so, but i have taco valves which funny enough if i take them off the zone will never open.
Old 10-16-20, 06:17 AM
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Hi, if this is a new problem I doubt it is a wiring issue, when you turn a Stat up the boiler starts, you remove the valve head and you get flow to the zone , sure sounds like a valve issue, post some pics and model#s of the valves and the boiler setup.
Old 10-17-20, 02:24 PM
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diynewguy should check zone switching relay, also called "zone controls"..

At the control relay terminals, when two wires from any thermostat to it are shorted/connected together, a circulator should start, regardless of thermostat status.

I install 120VAC pilot lights on each circulator to directly see their status, otherwise often difficult to know if powered activated and on.

Last edited by doughess; 10-17-20 at 02:43 PM.
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