# Which honeywell thermostat should I buy for my Carrier heat pump?



## beenthere (Oct 11, 2008)

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.


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## mannypp (Nov 17, 2009)

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?


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## beenthere (Oct 11, 2008)

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.


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## garya505 (Oct 9, 2009)

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


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## mannypp (Nov 17, 2009)

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.


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## beenthere (Oct 11, 2008)

Actually.
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.


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## mannypp (Nov 17, 2009)

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.


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## Allen797 (Nov 11, 2009)

mannypp said:


> 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.

Allen


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## mannypp (Nov 17, 2009)

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?


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## Houston204 (Oct 18, 2009)

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.


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## beenthere (Oct 11, 2008)

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.


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## mannypp (Nov 17, 2009)

*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.


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## beenthere (Oct 11, 2008)

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

Set up function.

1-5
2-0
3-1
5-3
6-3
7-3
8-3
9-3
12-your choice
14-0(for fahrenheit)
15-5
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


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## mannypp (Nov 17, 2009)

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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## beenthere (Oct 11, 2008)

To an extent yes.

The CPH is only accurate at 50% load(50% of your systems capacity to heat or cool the house). As it gets colder or hotter out.
It will do more or less cycles.

CPH is both a timing and temp difference algorithm(but not a lot of temp difference swing).


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## mannypp (Nov 17, 2009)

Off the top of my head I cannot remember what it is set at, but I am quite sure I left them at the default setting which is 5-5, 6-5, 8-9, 9-3, 10-3 (there is no 7).
5 is heat cycle rate
6 is second heat cycle rate/aux heat
8 is emergency heat cycle rate
9 is compressor cycle rate
10 is second stage compressor cycle rate


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## beenthere (Oct 11, 2008)

Oooops, 7 is only on the 5320 model.

5 CPH is too many for a heat pump. Waste a lot of electric. Takes too long for a compressor to get to its full efficiency.

You'll find better efficiency at 3 CPH of all heat and cool CPH on a heat pump.


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## mannypp (Nov 17, 2009)

OK, that makes sense. I'll switch all those down to 3.


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## mannypp (Nov 17, 2009)

I wasn't able to change from the default settings until last week because the house is out of state. Those default cycle rate settings managed to get me a $120 electric bill. The previous month was $20.

Another question I had was how come the manual says the heat cycle rate should be 9 for electric furnaces, emergency heat, and second stage heat/aux heat? Is a heat pump considered an "electric furnace"?

Also, what would happen if I changed the heat cycle rate from 3 to 2?


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## beenthere (Oct 11, 2008)

The aux and emergency setting of 9 is for comfort. Which is ok, if you don't mind the annoyance of 3 minutes on and 3 minutes off. Which at outdoor temps just below your heat pumps thermal balance point. Will keep the heat pump running 24/7.

Setting to 3 allows the heat pump to shut off when its just below your balance point temp outside. Which could be 35 degrees.

Setting the heat pump to 2 instead of 3 makes it run slightly longer. And can bring on the aux heat quicker.


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## mannypp (Nov 17, 2009)

beenthere said:


> The aux and emergency setting of 9 is for comfort. Which is ok, if you don't mind the annoyance of 3 minutes on and 3 minutes off. Which at outdoor temps just below your heat pumps thermal balance point. Will keep the heat pump running 24/7.
> 
> Setting to 3 allows the heat pump to shut off when its just below your balance point temp outside. Which could be 35 degrees.
> 
> Setting the heat pump to 2 instead of 3 makes it run slightly longer. And can bring on the aux heat quicker.


It seems that running 3 mins on and 3 mins off would cause the electric bill to be very high (which is what happened last month when the cycle rate was set to 5). And I definitely don't want the heat pump running 24/7.

Can you explain what balance point is?


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## beenthere (Oct 11, 2008)

Balance point.

There are 2.
1. The outdoor temp at which the heat pump can no longer maintain the set indoor temp.
2. The outdoor temp at which point it cost more to use the heat pump then the aux heat source.


There is really nothing wrong with a heat pump running 24/7. They are designed for that. But, many people just don't like it.

Often, it cost less to run the heat pump 24/7. Then for the heat pump to run for 10 hours and the aux heat to also come on for 4 of those 10 hours.


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## mannypp (Nov 17, 2009)

Makes sense. I think that the combination of the heat cycle settings set above 3 and the fact that the temps last month were in the high 20's at night and high 30s during the day for a week or two caused the $120 bill. I had the heat set to 60 while I was not there. The heat pump is in South Carolina on the coast. In the winter months, the temp tends to be in the 50's during the day and 40's during the night. I bet what was happening was that the aux heat (heat strips) in the air handler were on quite a bit during those cold days and using a lot of power.

In the install manual for the tstat, for the cycle rates, it refers to an "electric furnace" and the cycle rate of 9. Is a heat pump considered an electric furnace? I'm thinking not because that is counter to your recommendation of 3 for all the cycle rates.


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## beenthere (Oct 11, 2008)

An electric furnace is an air handler with strip heaters(in your case your aux heaters).


Even on electric furnaces(no heat pump attached). I don't set the CPH to 9. It also cycles the blower motor with the heaters. And that waste a lot of electric starting that motor back up every 6 minutes. 

I set the CPH to 3. And people like that MUCH better. Then 9CPH.


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## mannypp (Nov 17, 2009)

Great. I just want to validate the settings. The aux heat cycle rate set to 9 was probably causing the heat strips in the air handler to go on and off alot and wasting alot of electric.


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## beenthere (Oct 11, 2008)

mannypp said:


> Great. I just want to validate the settings. The aux heat cycle rate set to 9 was probably causing the heat strips in the air handler to go on and off alot and wasting alot of electric.


A 9 setting does waste electric.


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## mannypp (Nov 17, 2009)

Now that I have come full circle on all this, I realize that the same heat strips in the air handler are used for Aux heat and Emergency heat. That is why there is a jumper between E and Aux (Y2 and W2) in the thermostat. The heat pump itself is only a single stage system, the heat strips in the air handler provide the Aux heat. The Aux heat is the second stage and the thermostat is configured for a 2H/1C system.

With the combination of the very cold weather and the aux heat cycle rate set to 9 was most likely the reason for the high electric bill. I changed the setting on the thermostat to 3 right at the end of the last billing cycle, so we will see the result of these changes at the end of Feb when I get the next bill.


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## mannypp (Nov 17, 2009)

The only thing that might be a bit fishy about the thermostat wiring is that the E and Aux are jumpered together. The white wire coming out of the wall which I assume is the second stage heat circuit is connected to Aux (W2) and then there is a jumper between Aux (W2) and E (Y2). Does this seem correct to you? Should I expect a black wire to be connected to E (Y2)? The previous thermostat did not have a black wire connected to it. It had the same setup, Aux and E had a jumper between them and connected to the white (second stage heat) wire.


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## beenthere (Oct 11, 2008)

Nope. Thats pretty much standard wiring for many heat pumps where the aux and emergency heat is the same strip heater package.


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