Have Honeywell RTH7500 always use Aux Heat for Heat Pump


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Old 01-09-10, 10:14 AM
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Have Honeywell RTH7500 always use Aux Heat for Heat Pump

Is there a way with the Honeywell RTH7500 to have it always use Aux Heat for my York Heat Pump system? My heat pump outside is old and doesn't produce good heat anymore and when the system is within 2 degrees of the set temperature, it always blows cool air, eating up my electricity bill. When it is on Aux Heat, I get very warm air and it works well.

So the problem is that say it is 65 in my house, and I want it to be 70. When the tstat turns on, it goes into Aux Heat and gets to about 68 degrees, then turns off Aux Heat and stays in "Heat" mode. Then the system blows cool air and hovers around 67-68 degrees turning Aux Heat on and off a lot. It never gets to 70 unless I turn the tstat up higher, manually.

I know I have to replace my heat pump, but for now I just want to use my Air Blower's heat source to survive the winter.
 
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Old 01-09-10, 03:39 PM
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Use the mode button to select emergency heat if you only want the electric heat strips for heating.
 
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Old 01-09-10, 08:11 PM
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Just be aware, your electric bill is going to spike when you use the electric (emergency) heat.
 
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Old 01-10-10, 09:43 AM
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Originally Posted by Houston204 View Post
Use the mode button to select emergency heat if you only want the electric heat strips for heating.
I tried this and it still blows cold air. Regardless of Em Heat or Heat, it only gets warm when the tstat goes from "Heat On" to "Aux Heat On".

In Em Heat mode, it will either be in "Heat On" or "Aux Heat On" mode depending on the difference in target temp to actual temp, similar to how regular heat mode works.

Can I rewire the tstat so that everytime the heat comes on it goes into "Aux Heat On" regardless of what the front panel says? It seems to be the only way I get warm air.
 
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Old 01-10-10, 02:30 PM
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You could reprogram the stat to be heat only.

Here is the install guide.

http://customer.honeywell.com/techli.../69-2104ES.pdf
 
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Old 01-10-10, 03:27 PM
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Originally Posted by Jarredsdad View Post
You could reprogram the stat to be heat only.

Here is the install guide.

http://customer.honeywell.com/techli.../69-2104ES.pdf
Setting mode 170 from 7 to 3 doesn't turn on my Air Blower and Aux Heat when it goes to Heat On mode.
 
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Old 01-10-10, 06:06 PM
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Sounds like it only heats enough when the heatpump and electric heat strips are running.
 
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Old 01-10-10, 06:17 PM
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Originally Posted by Houston204 View Post
Sounds like it only heats enough when the heatpump and electric heat strips are running.
Right. It needs the heat strips because the heat pump is old and needs to be replaced.
 
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Old 01-11-10, 03:56 PM
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Sounds like we need to rewire the stat or air handler to make this work.

Post the colors and terminals at the stat and air handler. There is more than on way to make a machine do what you want, whether it likes it or not.
 
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Old 01-15-10, 05:45 AM
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W-> Aux
B -> C
G -> G
R -> R (with Rc jumpered)
X -> E
O -> O/B
Y -> Y
 
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Old 01-15-10, 06:58 AM
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If you are wanting extra heat for now you can move the Aux wire over to Y. Just be aware, your electric bill is going to jump up.

The aux heat will always come on when the hp is called for heat.


FYI, when comes summer, you must move the Aux wire back to to Aux, otherwise, the electric heat will come on when the A/C runs.
 
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Old 01-15-10, 12:59 PM
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Originally Posted by Jay11J View Post
If you are wanting extra heat for now you can move the Aux wire over to Y. Just be aware, your electric bill is going to jump up.

The aux heat will always come on when the hp is called for heat.


FYI, when comes summer, you must move the Aux wire back to to Aux, otherwise, the electric heat will come on when the A/C runs.
Well, if my Heat Pump blows cold air when its on Heat On mode and stay on constantly, cycling Aux Heat On and Heat On for hours, wouldn't that use more electricity than if I had the reliable strips heating up for a shorter time?
 
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Old 01-15-10, 01:49 PM
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I, at least, am under the impression that your heat pump is junk and you want to only run the heat strips for heat.

If this is true do as Jay said and move the aux wire to Y and remove and tape off Y.

If you are getting some heat with just the heat pump and need the strips to help reach temp move Aux wire to Y and leave Y in there.
 
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Old 01-15-10, 06:18 PM
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Originally Posted by tmar89 View Post
Well, if my Heat Pump blows cold air when its on Heat On mode and stay on constantly, cycling Aux Heat On and Heat On for hours, wouldn't that use more electricity than if I had the reliable strips heating up for a shorter time?
If it blows cold air, is the large line outside unit warm/hot? If not, it may be another issue.
 
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Old 01-16-10, 01:56 PM
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Originally Posted by Jay11J View Post
If it blows cold air, is the large line outside unit warm/hot? If not, it may be another issue.
It blows cool air, not cold air. It's not in AC mode, but it just doesn't work well anymore.
 
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Old 01-16-10, 04:55 PM
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Ok, LIke I said move the Aux wire to Y for now, then comes summer, move it back.
 
 

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