Replacing an old condominium thermostat

bokerman

Hi community,

thank you in advance for all the help.

I'm living in a condominium that has old thermostats (pic below):



The management can only replace them with the following ones and they charge 120CAD each?!
https://hsbuild.com/storage/product-pdfs/HVA50_Specifications.pdf

I asked if a "digital" one could be installed but didn't quite understand why they are not supported. They mentioned that tenants who did try to replace with a newer ones had controls inverted or something like that.

Could you please help me on how to connect something more modern, i would like to get something like this in the worst case scenario:
https://www.homedepot.com/p/Honeywell-Home-Round-Non-Programmable-Thermostat-with-1H-Single-Stage-Heating-CT87K/100476730

or even NEST if there is a way to connect it, but some 'digital' version with the scheduling temperature options would be just enough.

Steamhead

Might be a Series 20 control circuit. Some digital thermostats do support this, but have to be specifically programmed to do so.

HVACNUT

Agree with @Steamhead, it looks like Series 20, power open, power close.
The Honeywell T4 Pro would work but must be programmed for that setup.See note 5.

bokerman

Thank you so much for the help!

When you say programmed, is that a simple setting/configuration I would have to select in settings or it requires more than that?

Are these the ones you are thinking of:
https://www.amazon.ca/Honeywell-TH4110U2005-Programmable-Thermostat-Digital/dp/B075ZMQWMP/ref=sr_1_1?hvadid=604601316364&hvdev=c&hvlocphy=9000976&hvnetw=g&hvqmt=e&hvrand=9246723686341355441&hvtargid=kwd-398976636184&hydadcr=27855_14574558&keywords=honeywell+t4+pro&qid=1699205521&sr=8-1&ufe=app_do:amzn1.fos.b06bdbbe-20fd-4ebc-88cf-fa04f1ca0da8

https://www.amazon.ca/H1ywell-Home-Programmable-Thermostat-Th4110u2005/dp/B082MPRJNW/ref=sr_1_6?hvadid=604601316364&hvdev=c&hvlocphy=9000976&hvnetw=g&hvqmt=e&hvrand=9246723686341355441&hvtargid=kwd-398976636184&hydadcr=27855_14574558&keywords=honeywell+t4+pro&qid=1699205521&sr=8-6

bokerman

@HVACNUT @Steamhead could you please give me just a bit more of an assistance

Turns out the red wire doesn't do anything, it is not connected. So I thought this might be pretty simple, but it turns out it is not. I got the T4 Pro and tried different ways to connect.
So the fact to start with is if I disconnect the thermostat - the pipe is running hot through the condo. Neighbor tells me this is kind of a safety measure and they intentionally build it like this so in case of an power outage - heating will still work. It is somehow inverted. This is exactly how T4 Pro works now when connected, it is turning it on when it should turn it off and vice versa. I also tried to connect the wires opposite way but it is not helping.

HVACNUT

So the Red wire isn't connected to anything. 
What's the black and white wires connected to? Can we see?
What are you connecting at the T4, R+W or R+Y ?
 
I don't want to say without knowing what the thermostat wiring is connected to, but it sounds like a spring open, power close valve if it's only 2 wire.
If it is, then it should be R+Y and note 5 for the ISU.

mattmia2

What does that t-stat control? Do you have access to the other end of that wire?

mattmia2

If it is a normally open valve then you would need a professional t-stat that can be programmed to open the contacts on a heat call and close the contacts when the call ends. You could also use a regular t-stat with a relay and a 24 vac wall wart. That would let you power a "smart" t-stat too.

bokerman

@HVACNUT many thanks for the comment.

I don't really understand the note 5, what is ISU? I see three modes on the thermostat menu, Heat, Cool and OFF. There is nothing more in the Menu except from clock setting and similar. Again, thanks a lot for the help!!

Here is how it looks right now, it is basically acting inverted (turns on when it should turn off):

mattmia2

Could you get a good picture of the markings on the valve? If it is a normally open valve you can either get a t-stat that supports that or you could put a relay at the valve that inverts the action of the t-stat since you have access to the transformer at the valve.

tim smith

If you went with a honeywell TH6110D1021 your could set up for heat only in setup, radiant heat. Then in wire diagram for thermostat they show for zone valve Normally open type, use Y terminal to close. That's what it looks like to me. So any time a call for heat, power is removed to zone valve which allows valve to open. Then when heat is satisfied the Y terminal gets power and closes zone valve. Look at 4th down diagram on attached, left side to see what it references. Looks like might fit the bill.

HVACNUT

bokerman said:

@HVACNUT many thanks for the comment. I don't really understand the note 5, what is ISU? I see three modes on the thermostat menu, Heat, Cool and OFF. There is nothing more in the Menu except from clock setting and similar. Again, thanks a lot for the help!! Here is how it looks right now, it is basically acting inverted (turns on when it should turn off):

I'm not 100% convinced that's a Normally Open zone valve, but if it opens when then wires are disconnected and not touching at the thermostat, then... ISU is Installer Setup. You need to access it and go through the prompt so the thermostat knows what to do. Wire R+Y and do Step 5 and see what happens. 

bokerman

@HVACNUT YOU NAILED IT!

I don't know how to thank you enough. No one in this condominium knows how to set this up, I've been living here for 9 now.

Please let me know if there is anyway I can contribute to anything that would make some difference important to you.

HVACNUT

bokerman said:

@HVACNUT YOU NAILED IT! I don't know how to thank you enough. No one in this condominium knows how to set this up, I've been living here for 9 now. Please let me know if there is anyway I can contribute to anything that would make some difference important to you.

I've always dreamed of being independently wealthy, but the thank you is just as good. You're very welcome. 

bokerman

mattmia2 said:

What does that t-stat control? Do you have access to the other end of that wire?

I haven't seen your comment until now, sorry. Wiring R+Y and doing Step 5 solved the issue.

bokerman

mattmia2 said:

If it is a normally open valve then you would need a professional t-stat that can be programmed to open the contacts on a heat call and close the contacts when the call ends. You could also use a regular t-stat with a relay and a 24 vac wall wart. That would let you power a "smart" t-stat too.

Thanks again for the help!

bokerman

mattmia2 said:

Could you get a good picture of the markings on the valve? If it is a normally open valve you can either get a t-stat that supports that or you could put a relay at the valve that inverts the action of the t-stat since you have access to the transformer at the valve.

Couple of owners were talking about that an invertor is necessary but luckily there is a simple solution with the config @HVACNUT provided.

bokerman

tim smith said:

If you went with a honeywell TH6110D1021 your could set up for heat only in setup, radiant heat. Then in wire diagram for thermostat they show for zone valve Normally open type, use Y terminal to close. That's what it looks like to me. So any time a call for heat, power is removed to zone valve which allows valve to open. Then when heat is satisfied the Y terminal gets power and closes zone valve. Look at 4th down diagram on attached, left side to see what it references. Looks like might fit the bill.

Thank you for the post. I believe this is what worked but only with T4 Pro: Wiring R+Y and doing Step 5 (Step 5 was Setting to Radiant heat (200 to 5) and number of stages to 0 (220 to 0). There were couple if T4 Pro for 15-20$ each on Facebook Marketplace, I couldn't be more happy.