Zone valve for upstairs will not open. Already replaced thermostat. The only time I have heat upstairs is when the valve in manually opened and the downstairs heat kicks on. Any help or advice would be great! Thank you.

I am going to throw this out here and I hope I don't confuse you even more. I am not an expert by no means in this field so I hope an expert can back me up or be able to eliminate what I am about to say. First of all, is this hot water system? If so, it sounds similar to what I just went through. I don't understand it myself so bare with me. What I have is a closed 2 zone system system for both upstairs and downstairs. After the guy replaced my boiler the same thing was happening as was before (no heat going ot upstairs). He found that one of the thermostat wires had a short in it(broken wire) that went to the transformer. The other problem was the feeds to the radiators were set up incorrectly and had to be reversed going to the zone valves. I guess the question would be is how long has this been happening or better yet, did it just start to happen? My uneducated guess would be possibly the wire to the thermostat is broken. I would wait for an expert to respond before doing anything though. Hope this helps.

It is a hot water system. It's always worked before, it just all of a sudden stopped working. I don't know if the valve is broke or I thought maybe it is the wire from the thermostat to the valve. Thank you.

One other thing that professionals have said is that there could be air in the syste, Have you tried to purge the system of air? Unfortunately there could be one or more problems related to this so it might be hard for anyone to diagnose this here. When one of the other experts responds they hopefully will have ideas to step you through the process and give more detail one what I have said. Bleeding the system will never hurt so you may want to try that. One more thing to think of. Good luck!

Maybe pooling our ignorance here, we can figure this one out. You need to know which terminals on the valve should be hot to open the valve and turn on the boiler. I lucked in about a year ago and found a great guide on the White Rogers website. If you can't find anything on whatever you have, go to the valve that is working and check it. Some valves work by having the white wire from the thermostat activate a relay. The relay turns on the motor for the valve. The valve opens, and turns its motor off, and the boiler on. When the thermostat cuts power to the white wire, the relay switches power to a different contact on the valve, restarting the motor. The motor then shuts the valve, shuts itself off and shuts the boiler off. Yeah, it really works that way, honest.

The White Rogers valve had 6 contacts. If a wire to one of them is broken, it won't work right. The wire breaks easily and can have a broken conductor hidden under the insulation.

I had the same problem. 3 zones with baseboard hot water. Checked the wires on the valve and sure enough one was loose. Tightened it up and it works like a charm. Good luck!