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Sanderella 11-01-2010 04:57 PM

Thermostat replacement
Hi all!

I live in a condo with gas forced air heat/AC. I decided to replace my thermostat, so I bought a standard digital honeywell.

When I removed the old thermostat, I discovered that there are more wires in the old one than there are spaces to insert wires in the new one. Both the old and new are "generic" thermostats. In the new one, there's the traditional Rh, Rc, W, Y, and G. But the wires in the wall are these, plus 4 more.

What do I do?

Sorry if this seems like a silly question. I'm usually pretty good with electrical work, but this has me confused.


1910NE 11-01-2010 09:17 PM

i just replaced my thermostat (with a basic Honeywell model.) my furnace is oil fired hot water, so thats where our similarities end. read the installation instructions for the new one. It will tell you which wires to use, based on the type of furnace that you have, and which to ignore.

edit: The installation instructions will also tell you if that model of thermostat will NOT work for your furnace.

hvac122 11-01-2010 09:31 PM

You may have a heat pump or staged heat, May not be right t-stat you bought.

Sanderella 11-01-2010 10:21 PM

Thanks for the tips, guys!

I'm sure I'm on a standard gas forced air. I live in a new high-rise condominuim building.

The installations instructions with the unit say to simply wrap the excess wires (if there are any) in electrical tape and tuck them into the wall! I thought that was odd, but I did it anyway, and the thermostat isn't working.

I think my first issue is that the wires in the old thermostat weren't labelled. Nor were the connections in the old thermostat labelled I attached the first five from the old one in order into the new one, and wrapped the last 4.

If simply wrapping the excess 4 WERE the solution (but, seriously, really?), then I would assume the order of the first 5 is incorrect. But that doesn't get me anywhere either.

If I were to call an HVAC service company, would they have a method of determining which wire goes where?

This might be my first (and most embarrassing) DIY failure. I can replace light fixtures and do some mean plumbing, but thermostats have me baffled!

beenthere 11-02-2010 05:01 AM

The instructions to wrap the excess wires. Means if they weren't used on the old thermostat. if they were used. then you can't just wrap them and tape them.

Look at your heating system. Is it a gas furnace? Or is it a heat pump?

A service tech will look where the wires are connected at your heating and cooling system, to know where they go on your new thermostat.

Sanderella 11-02-2010 09:31 AM

Somehow, I guess I'm not making myself clear here...

I live in a condo highrise, which means I don't have access to the actual firnace at all. All I have in my unit is the filter for the air intake, and the wires for the thermostat.

But, I am 100% positive that we are on a gas, forced air heating and cooling system (I'm also a realtor and need to be sure about these things).

So I *can't* look at the furnace to figure out what it is, but I already know anyway, so it's not an issue.

I guess I'll look elsewhere for assistance. Thanks anyway, guys!


beenthere 11-02-2010 06:38 PM

Has to be some way to access the heating unit.

Without knowing what you have. No way to tell you what wires go where.

Might want to talk to one of your neighbors. Good luck.

Artco 11-02-2010 07:02 PM

Are the terminals maked with letters on the old thermostat for all the wires that were connected to it?

Artco 11-02-2010 07:06 PM

Look real good for tstat wire markings.
What is the model and mfg. of the old thermostat?

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