Any HVAC dads out there?

[chefchuckv]

I am trying to put in a programmable thermostat. I figured it would be as easy as matching up the colored wires...ummm, no. :huh:

The existing digital thermostat has contacts marked G-O-B-Y-W-C-R
A green wire is attached to the G, a yellow wire is attached to the Y, a white wire is attached to W, a blue wire is attached to the C, and a red wire is attached to the R. Nothing is attached to the O or B.

I was hoping the new programmable thermostat whould have identical markings. What was I thinking #-o

The new thermostat has contacts marked G-Y-W-RH-RC and there is a bridge pre-wired between the RH and RC. I assume the G, Y and W are the same setup as the original. But where do I connect the blue and red wires? Do I keep the bridge in place?

This is for a thermostat for heat and air. It is not a heat pump. Any help would be appreciated!

[sao95]

if it were me I'd attach the c to RC and the r to RH, if it's wrong it simply won't work, shouldn't blow anything up ;)

[woodchuck]

RC = cooling
RH = heating

just one wire needed for the two since there is a jumper in place.

YOu can look at the connection terminal block in your furnace, just follow the thermostat wire, see how that's connected.

Have you read the instructions? Old to new is generally not very difficult.

Hey Jeffus...

[jim]

Some HVAC systems use one wire for the furnace and the AC, hence the jumper. Other systems use a separate wire for the two.

your blue wire should be your AC and the red your furnace.

RH is heat RC is AC

Check the instructions for the new thermostat. You may need to remove the jumper or you may just have to connect both up with the jumper in place depending on exactly how the new thermostat is made. If the instructions are not clear on this try the manufacturers web site. Sometimes they will post more detailed instructions or have a FAQ there.

[jeffus]

Hey Jeffus...

Urrr......What?

I took a day off! mmkay?


OK, wiring should be done by now....Here's the next challenge: On the back of the unit, there should a switch arrangement that tells the themostat what type of heating system you're running - baseboard hot water, forced hot air, boiler steam (rare these days), radiant, etc. Each of these system configurations have wildly different thermodynamic/heat transfer dynamics.

The setting you choose here will directly affect your comfort this winter! Choose wisely!

All of the wiring for thermostats is low voltage stuff. You're not going to hurt anything. So don't worry about 'experimenting'.

However - a basic wiring 'convention':
Green = ground - always!

If the manufacturer installed a jumper - it's there for a reason. If it needed to be removed, they put a note or tag on it telling you to remove it for a specific reason.

Good Luck!

[Hockeyfan]

Your house is brand new isn't it? Didn't they have a programmable one in there? What kind of houses are they building in Morrisville?

[chefchuckv]

Thanks everyone. I will try that today. I am just paranoid about frying the circuit board since I just had to replace one for $500 last month - no idea why a 5 yr. old board fried - the tech had no answers! It must be those cheap Morrisville houses! Gotta love Pulte Homes...

[chefchuckv]

OK. So I called the HVAC company that did the $500 circuit board work a couple of weeks ago. They wanted to charge me $95 to come out and install the thermostat. So I whined to them a little and they agreed to have a tech call me at no charge. Turns out the blue wire is for power to the thermostat. Since the new one runs on batteries, I just needed to cap off the blue wire and connect the red one to either of the RH or RC terminal keeping the bridge in place. I tested them both and nothing blew up and both heat and A/C work. It would be so much easier if there were standard conventions for HVAC like there are for electrical...

One more project under my belt - albeit not a major one.

Thanks for everyone's help!