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mannypp 11-17-2009 11:00 AM

Which honeywell thermostat should I buy for my Carrier heat pump?
I have a Carrier heat pump (model 38YCC030340) and a Carrier air handler (model FA4ANF030). It currently has a honeywell thermostat that has OFF-HEAT-COOL-EM. HEAT options. I want to replace it with one that has those four options plus an AUTO feature. I want the AUTO feature so I can set the upper temp for the AC to go on and a lower temp for the heat to go on without having to worry about switching it from HEAT to COOL or COOL to HEAT.

I am interested in the FocusPRO line. The models whose model numbers look like TH5XXXXX. I do not need it to be programmable, but I do want it to be digital. The problem I am having is I don't know how many heat and cool stages my units have. I know the TH5220D1029 is for 2 heat and 1 cool, TH5220D1003 is for 2 heat and 2 cool, and TH5320U1001 is for 3 heat and 2 cool. How many heat and cool stages does my Carrier heat pump and air handler have? and which thermostat is right? I am also open to other thermostat brands.


beenthere 11-17-2009 12:00 PM

Your heat pump is single stage.

But, your air handler could have 2 stages of electric heat.
There ain't that much of a price difference between the Th5220 and the TH5320.

So get the TH5320, and your covered.

mannypp 11-17-2009 12:38 PM

So I assume that it doesn't matter how many stages the thermostat is designed for. True? I assumed that you needed to match up the thermostat based on the number of stages the heat pump and air handler have.

What the difference between the thermostats is?

beenthere 11-17-2009 02:32 PM

Stat just needs to support the number of stages of heat you have. If it has more, no problem. It just won't use the extra ability, because you tell it how many stages your equipment has. When your in installer set up.

The 2 heat 1 cool, will have a W1 and W2 terminal, and a Y terminal.
The 2 heat 2 cool, will have a W1 a W2 terminal, plus a Y1 and a Y2.
The 3 heat, 2 cool. Just has an additional terminal marked W3.

garya505 11-17-2009 02:42 PM

Personally I like White-Rodgers thermostats (I have one), but you should listen to 'beenthere', he knows his stuff.

mannypp 11-17-2009 02:49 PM

For a few bucks more, it makes sense to get the TH5320U1001 even though I won't use the extra stages. I know that the heat pump has heat strips and that the air handler also can supply emergency heat. So I guess that means that I have 2 heat and 1 cool stages. So I will use the W1 and W2 and Y1 and the other W's and Y's will be unused. I will verify the current setup with the thermostat that is there which is also a honeywell, but without the AUTO mode.

Anything else I should know about changing the thermostat? I plan to turn the power off to the heat pump and air handler, switch out the thermostat, and then turn the power back on. And yes, I will mark the wires that are there before I disconnect the current one.

beenthere 11-17-2009 03:13 PM

It would be W2 and W3 for heat pumps with aux heat.
On the TH5320, W1 is also the O/B terminal for heat pumps. So its not used for aux heat. Read instructions carefully before installing.

mannypp 11-17-2009 03:19 PM

Right, I plan on making sure I read those instructions and get it right the first time. Actually, I downloaded the installation instructions from the site.

Allen797 11-17-2009 03:23 PM


Originally Posted by mannypp (Post 354373)
Right, I plan on making sure I read those instructions and get it right the first time. Actually, I downloaded the installation instructions from the site.

Smart move I wish you luck.


mannypp 11-17-2009 06:54 PM

One more question, when you say the heat pump is 1 stage, I assume you mean 1 cooling stage and 1 heating stage. Correct? Does emergency heat count as a stage?

Houston204 11-17-2009 08:19 PM

TH5220D1029 = 2 heat 2 cool large display
TH5220D1003 = 2 heat 2 cool small display

Whatever you choose, I recommend the larger display. It will end in 1028 or 1029. I probably have these stats on a shelf in my van now. The 22 in the model number indicates 2 heat/2 cool. That TH5320 would allow for a 2 speed heatpump upgrade in the future.

beenthere 11-17-2009 08:20 PM

Heat pump stages. Refer to how many stages the heat pump itself has.
And in your case. Yes, 1 heat, 1 cool.

Aux, and emergency heat, are not stages of the heat pump.

mannypp 12-28-2009 06:15 AM

Finally got to hooking this up
It is over a month later and I am finally getting to hook this up. I bought the TH5220D1003. I have it hooked up and the heat and cool work correctly. However, it seems the heat is lukewarm. With the previous thermostat I know it was warmer because I turned on the heat two nights ago and it was working well and generating more heat. Here is the difference. I have configured the thermostat to 1H/1C with no Aux heat. There is no setting in the thermostat for 1H/1C with Aux heat. In the old thermostat, the E and Aux were jumpered together and the White wire going to them. The next best configuration setting on the thermostat is for 2H/1C with Aux heat. The installation manual for a 2H/1C heat pump system indicates Aux (Auxiliary heat relay) and E (Emergency heat relay) with a note that a field jumper should be installed between Aux and E if there is no emergency heat relay. Since my old thermostat had the jumper between E and Aux, could it be that they were using emergency heat as auxiliary heat or as the second heat stage? I think I am going to change the configuration on the thermostat to 2H/1C with Aux heat and put a jumper between E and Aux (like it was on the old thermostat). But will wait until later today to see if I hear from anyone on this forum.

Side note: in the installation manual for 2H/1C heat pump systems, it does not indicate the use of W2 for anything.

beenthere 12-28-2009 08:30 AM

Thats because W2 and Aux. Are the same terminal. And it tells you to connect Aux heat to the Aux terminal.

Set up function.

12-your choice
14-0(for fahrenheit)
26-0 for comfort, 1 for economy if you don't mind being a little cooler when it gets cold out
27 leave at default
28 leave at default

mannypp 12-30-2009 07:28 AM

For the cycle rates (setup functions 6 to 9), does that just control how many times the unit will turn on and off in an hour?

BTW-everything seems to be working fine. Thanks for he help.

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