Can someone please recommend a non-programmable digital thermostat for a heat only 24 Vac system? Normally open valve.

Honeywell Pro5000 is a great stat and will work with your system. Just make sure to change the batteries once a year if you don't have a third wire for common. Also, read the install manual from front to back so you can set the stat up for your exact system. No matter what stat you decide on, I would suggest going with a honeywell product, as they are the leader in thermostats.

Honeywell Pro5000 is a great stat and will work with your system. Just make sure to change the batteries once a year if you dont have a third wire for common. Also, read the install manual from front to back so you can set the stat up for your exact system. No matter what stat you decide on, I would suggest going with a honeywell product, as they are the leader in thermostats.

Thank-you for this quick answer. It is a two wire system. Would you know which terminals to use on the Honeywell Pro 5000?

One wire to r, and one wire to w. Doesn't matter which wire goes to r, or w, just one to each. You can leave the jumper in between r and rc, or take it out, doesn't matter. Is this a forced air furnace, or boiler(hot water heat)?

If you can tell me what type system you have I can walk you through the simple stat setup for your system. Remember, with only two wires, the stat will be powered by batteries, so if the batteries die, the system will not work. Very important to change batteries once a year.. there is a low bat indicator to remind you.

one wire to r, and one wire to w. Doesnt matter which wire goes to r, or w, just one to each. You can leave the jumper in between r and rc, or take it out, doesnt matter. Is this a forced air furnace, or boiler(hot water heat)?

Thnaks for your help. Much appreciated. It is boiler system.

OK. You will be looking for Honeywell FocusPRO TH5000. Model-TH110D

Now for hot water (boiler) you will put one wire to r and one to w. Insert batteries and push and hold the top right and bottom left buttons at the same time until the setup screen comes up (only takes a few seconds). You will see a 1 on the left and 0 on the right. Use the up arrow to move the right number to 2 (this is for heat only 2 wire systems). Next, hit the right bottom button until you see a 5 on the left side. Use the down arrow to move the right number down to 3 (this is for hot water heat systems). Then simply hit the bottom left button for DONE and your all set. Please let me know how things work out. All of this is in the installation manual.

PS. If you have any way to run an extra wire for a common, I would suggest doing it. If you can get the common (c) wire hooked up, you can take the batteries out and the stat will still work.

OK. You will be looking for Honeywell FocusPRO TH5000. Model-TH110D

Now for hot water (boiler) you will put one wire to r and one to w. Insert batteries and push and hold the top right and bottom left buttons at the same time untill the setup screen comes up (only takes a few seconds). You will see a 1 on the left and 0 on the right. use the up arrow to move the right number to 2 (this is for heat only 2 wire systems). Next, hit the right bottom button untill you see a 5 on the left side. Use the down arrow to move the right number down to 3 (this is for hot water heat systems). Then simply hit the bottom left button for DONE and your all set. Please let me know how things work out. All of this is in the installation manual.

Excellent. Thanks very much for your help. I will try to find one locally and let you know how it worked out. Cheers!

Did you say it had a normally OPEN zone valve? If so, what closes the valve?

Good question, Grady. I missed that. It may be a three wire zone valve that requires power to open and power to close. However, if there were only two wires at the old stat, two wires should work the same on a new digital stat. If it is indeed a three wire zone control valve, there must be a zone control box that takes care of the power on close when the call for heat is ended by the stat, other wise the old stat would have had to have three wires to it. At least that's the only way Ive see it done. Your thoughts?

The only normally open zone valves I've seen were used on a solid fuel boiler. The thermostat, via the Y(?) terminal, closed the valve. They used some kind of relay with a rectifier. Can't remember the brand of valve but probably would if I heard it again.

rpc66: What is the make & model of the zone valves?

Hello Mygirlsdad and Grady
I live in an apartment style condo (mid 70's) which is heated by boiler system (water/glycol). In my apartment unit I have one thermostat (2 wire). The valve is Honeywell V8043D1205 24V 60 Hz. I had an HVAC tech come in for a problem that began 3 months ago. He told me the valve was normally open. I am hoping he is correct on that?

The problem is.. we lost most of our control of the heat in our unit. It seems to cycle on it's own no matter what temperature we try to set it at. The HVAC tech said he believed some repairs were done with the transformers in the boiler room and we may be piggied back onto someone else's unit. He was here last Friday and said he fixed it... but this weekend proves otherwise.. still doesn't work right. Another problem is the heat works backwards on two different thermosats. I believe this is where the conversation led to normally open and closed valves? Do I need a thermosat for a normally open valve in order for the heat to work correctly?

You do need a thermostat for a normally open valve (reverse acting thermostat). I searched Honeywell's site to no avail other than a T822C which, it seems, is no longer made. There has to be a replacement but I can't find it.

Dad?

I honestly haven't dealt with the normally open valves. I suppose you could still use a standard stat, set it to cool and use the rc and y terminals, but that would get awefull confusing for future tenants. I would think you would still want to use a standard stat but the correct relays to control the power to the actuall zone valve must be in place.

All in all, I think you need to get the tech back, or even a different one to figure this whole mess out. Im quite certain that its not so much a matter of thermostat, but more about having some sort of zone control box, relay, etc, that can properly power , or "un-power" the zone valve when the stat is calling for heat. Im curious to hear how this all turns out. Kind of wish I could be there to see this first hand. Always up for a learning experience.

Right now I have a standard stat on with terminals y and rc being used (set to cool) as you mention and it was working fine until they messed with the wiring down below. Yes, it will be confusing for a future buyer. As you say, a new stat will only solve a part of the problem. Maybe I will be able to find a T822C that Grady mentions. That will solve the backwards situation. Thanks for all the advice and input here. Very much appreciated. I will report back with the outcome.