Conflicting info on wiring a new thermostat

[mdonovan]

I've followed the discussion about the WiFi Radio Thermostat and its open API. Exactly what I've been wanting. I took a look at my current thermostat and this is where I get confused. I've installed replacement thermostats before, but this one I have now looks different.

I have a heat pump, with an oil furnace for axillary heat. The thermostat has 3 wires, red, white, and blue. The connectors the wires are connected to are labeled 1, 2, and 3.

In searching the web I have found responses from just hook this wire to this terminal etc, to you can't use just any thermostat with this type of system, you need a special one.

So is anyone familiar with this type of 3 wire thermostat (I can't find the manufacturer listed on the unit anywhere) and replacing it with a new model like the Radio Thermostat? I'm going to ask Radio Thermostat this too, but I wondered if anyone here had any ideas.

Thanks

Matt

 

[wuench]

Did you look at what the terminals say on the furnace side or is that where it says 1..2..3?

 

[tmbrown97]

Can you post a picture?

There's a good chance you'll need to run another wire - I'm pretty sure a heat pump with aux uses a minimum of 3 wires and that leaves no dedicated power.

If the existing thermostat isn't labeled any better than 1,2,3, you may be able to google an installation manual for it to find a legend... or even look at the other end to see if what they're connected to is any clearer.

 

[mdonovan]

I'll take a closer look at it tonight. There are extra wires already run to the thermostat, they are all just coiled up behind it. I'll get a pic and I'll see if I can figure out where they are connected at the furnace. There is a small control box on the furnace that I have to open up to see where they go. I'm glad I looked at this before I went ahead and bought the new tstat.

Matt

 

[rsw686]

It sounds like a proprietary communicating thermostat. You might get lucky and the control box is a separate controller for the thermostat and has the usual terminals inside that are wired to the HVAC. You might want to look for the install manual for the HVAC unit.

 

[mdonovan]

I removed the cover on the control module and everything is labeled on there. Apparently it's a Honeywell Visionpro IAQ. From looking at the control module it appears to have all the standard wire labels in it, except for the 3 wires that come from the thermostat. They are also labeled 1, 2, and 3. These 3 connections are shown on the diagram as Communications Terminals.

I am trying to ask Radio Thermostat about this but their forums seem to be permanently under maintenance. Not sure what I'm going to do right now. I'll have to study it some more. It will really suck if I can't replace the thermostat with another one. This Radio Thermostat is something I've been interested in for quite a while.

Matt

 

[fcwilt]

You've got a 2 piece "smart" tstat. The wiring from the control box to your HVAC gear is pretty standard fare. The three wires from the control box to the wall unit are probably a power, a ground and a signal line. The likely used typical 8 conductor cable and used only three of the wires.

If so you are in good shape in that you can connect most any tstat that expects to connect directly to the HVAC gear.

 

[rsw686]

I found the manual for the VisionPro IAQ thermostat. The thermostat interface is separate from the thermostat control unit and uses a three wire connection between them. The HVAC unit connects to the control unit with the normal connections. You will need to remove the control unit and cap the thermostat wires together by color. Then wire the new thermostat per the directions.

https://customer.honeywell.com/resources/techlit/TechLitDocuments/68-0000s/68-0287.pdf

 

[mdonovan]

I understand now. Thanks everyone very much for the help. I see what I need to do. I appreciate the information.

Matt