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mason82 09-11-2008 03:28 PM

condo thermostat change
I want to install a digital (programmable) thermostat in my condo. The current thermostat is connected to two red wires in the wall; two black wires are spliced together. The heating is though hot water registers in the main room and the bedroom.

I measured the voltage between the red wires and I think I remember it being about 30 Volts--the thing is I measured it on AC mode so now I'm not sure if I need to go back and double check the voltage to see if it's AC or DC... obviously I'm not too familiar with thermostats...

Anyway, if there is an obvious answer to the following question, let it be known: What kind of thermostat do I need to install? Any recommendations?


SD515 09-12-2008 08:36 PM

Find your transformer and look for a label/stamping that states it's rated voltage (should be AC voltage). It could be a 24V x-frmr putting out 30V...seems a little high, but there are variables involved. If it's 24V you should be able to hook up a digi-stat, but you'll need to determine which of the red wires is supplying the 24V, which can be done with a volt meter and an extension cord. Turn the stat off (or turn it way the heat doesn't want to kick on) put one test lead into the ground hole of the ext cord, and touch the terminals of the red wires. One should show 0V and the other 24V. The one showing 24V will go on the 'R' term of the new stat, and the other (red) will go on 'W' of the stat. Leave the 2 blacks as there are.

As far as what digi-stat to get...get what you like...I wouldn't go 'over-board' as this stat only does heating cycle, right?? No A.C. ??

mason82 09-12-2008 10:15 PM

Great response!

Correct--the thermostat is only for heating.

How do I know if a thermostat is designed to use with the 24VAC that will have the "R" and "W" terminals... maybe what I'm getting at is, is there a category or type of thermostat that I should be looking for (e.g. I'm pretty sure I'm not looking for ones that say "For electric baseboard heating")?

Thanks again!

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