[sellstuff]

We've got a 1990 Carrier 58GSC model HVAC gas furnace / AC that still has it's original twin Mercury switch Thermostat. This Carrier Furnace/AC is a 4-wire connection to the Thermostat and I'm having a tough time finding a good but cheap Digital Thermostat with many 3 to 5 programmable setup that's 4-wire or states in the advertising specs that it is compatible with a 4-wire furnace.

This Honeywell carried at Lowes is what I'm looking for, but it says no where whether it's 4-wire compatible. https://www.lowes.com/pd/Honeywell-Basic-Digital-Programmable-Thermostat/3464340

Any suggestions out there for a particular brand or model that's 4-wire compatible similar to the Honeywell referenced above in the $30 to $45 price range?

 

[user_12345a]

Most basic thermostats are 4 wire.

If you have the letters R, y, G, W at the stat, you can use any.

You can often use fancier t-stats with 4 wire systems, you just program them properly for the system type.

 

[beenthere]

Thats a battery operated thermostat, so you cn use it for your system.

 

[sellstuff]

I have a new in the box Honeywell CT2400A I bought about 10 years ago for another house I owned and never used it. It is for 4-wire systems, BUT it says it's for "24 volt systems".

How do I determine if my Carrier 58GSC model HVAC gas furnace / AC is 24 VAC? I don't see any reference on the schematics to the voltage for this system?

This is the PDF for the Carrier 58GSC Furnace. http://dms.hvacpartners.com/docs/1005/Public/03/58GSC-5SI.pdf

Honeywell CT2400A Digital Therm

 

[user_12345a]

your system is 24v.

 

[sellstuff]

your system is 24v.

Just for my learning process about Furnaces, what part of the system is running on the 24 VDC? The furnace has a direct 120VAC connection, which is fused at the main panel box.

Thanks.

 

[user_12345a]

All the controls are on 24v ac, not dc.

thermostat, relays, contactors, gas valve, ignition control.