Hello,

I am trying to install a new Honeywell RTH7500 thermostat to replace my Robertshaw 9200 thermostat.

The Robertshaw 9200 had the following connections:

One yellow wire that was connected to W and Y (the wire is long and was threaded underneath the screws in the W and Y connections);
One white wire that went to the O connection;
One green wire that went to the G connection;
One red wire that went to the Rc connection (that had a jumper to the Rh connection)

I wasn't sure what type of system I had but according to the Robertshaw 9200 installation manual, this was the connection for a heat pump system with cool active reversing valve.

The manual for the new Honeywell thermostat has a diagram for heat pumps as follows:

Yellow to Y
White to O
Green to G
Red to R

Notice no W (whereas the Robertshaw had the yellow wire connected underneath Y and W). I programmed the thermostat according to the heat pump directions in the manual. But when I turn on Cool, I get warm air!

I called Honeywell and the technician had to put me on hold to ask someone who came back with "Y only goes to Y, you don't need to split the wire." :huh:

But I still get warm air. Any help or insight would be appreciated -- I am at a loss.

Do you by chance have a zoned heat pump system.

One heat pump and 2 thermostats?

No, it's not zoned as far as I can tell. I just have the one thermostat and a small condo.

Put the white wire on "w" if you don't have a "o",

Ahh! A condo.

The Robertshaw stat has a separate O & B terminal. That is not normal: Manual here: http://www.icca.invensys.Tcom/manuals/robertshaw/110-956b.pdf but that's not an issue with you.

The Honeywell Here: http://customer.honeywell.com/techlit/pdf/PackedLit/69-2104ES.pdf

On page 20, you set the state of the O/B terminal. You have a wire to O/B, not O. The parameter 190 should be 0 for and O terminal. 1 for a B terminal. If they are backwards then heat and cool are reversed.

Parameter 0170 should probably be set to 2.

If this is really a separate heat pump

There are some systems that connect W and Y together. Those systems usually have the heat/cool modes set at the furnace.

Thanks keepitsimple! Turns out I had a loose wire, tightened it and then turned it on, making sure the settings on the screen were correct. Voilà! Cool air.

Cool air? I can get waay tooo much of that by just opening a window...