Adjusting Aux heat runtime

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Old 01-26-15, 05:23 PM
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Adjusting Aux heat runtime

Is there a way to adjust how soon the Aux heat kicks in and make it run at the same time as the heat pump?

I would like to reduce the furnace run time but not go to full E-Heat. If I lock out the heat pump below 25 degrees on my Honeywell 8600 Tstat my electric bill skyrockets in Jan and Feb. If not locked out the heat pump runs and runs but Aux never comes on.

How do you get a happy medium where the heat pump and aux run together? I don't mind a slightly higher electric bill to reduce run time but full Eheat is too expensive.
 
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Old 01-26-15, 05:38 PM
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You'd be better off leaving the heat pump run even if it's full time and just let the reheats come on when the heat pump can't keep up.
 
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Old 01-27-15, 07:31 AM
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I have to leave a window open to get the aux heat to come on. I guess I have a tight house.

The heat pump runs and runs and runs at night when below about 35. How can I get the aux heat to come on for a touch to reduce wear and tear on the heat pump?
 
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Old 01-27-15, 08:22 AM
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Usually the AUX will kick in when the temperature setting is three or more degrees above actual temp.

This point would signify that the heat pump couldn't keep up and the AUX would come on.

I don't see any changeable steps for that setting in the t'stat menu.
 
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Old 01-27-15, 01:03 PM
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It depends on what the Heat Pump and thermostat manufacturers decided should be the mode of operation, if you had the documentation describing how the AUX is controlled, maybe a change of settings would accomplish what you'd prefer.
In my case, similar to yours, I found that a different thermostat could do the job.

You might read:
http://www.doityourself.com/forum/he...ifference.html

as usual, the final resolution of the problem wasn't posted ...
 
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Old 01-27-15, 01:21 PM
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Anytime the electric heat comes on, efficiency goes down the drain. If the system is maintaining indoor temperature, then there is no reason for Aux to come on.

Let it run, that's what they're designed to do.
 
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Old 01-27-15, 02:19 PM
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The more efficient the heat pump the more relatively expensive it is to run the aux heat. Having a thermostat that can optimize and adjust the balance between the two would seem to be highly desirable.

The balance is a matter of opinion, ranging between lowest electricity costs, to least running of the heat pump and air handler.
 
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Old 01-28-15, 05:35 PM
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Does this setting on the Robertshaw 4320 turn on the Aux after the heat pump runs for a while? I wonder what the optimum setting is for this? 5 minutes or more?

Second Stage Delay = This timer starts when the first stage turns on. It resets when the first stage turns off. If this timer runs out the second stage will turn on...
 
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Old 01-29-15, 05:32 AM
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The second stage heat delay time can be set from 5 to 40 minutes in 5 minute steps.

It is easy to change and I change it depending on the weather, occupancy, comfort importance ,etc..
I have the second stage connected to 5 kw of the AUX heat. Depending on conditions I change the delay time.
At one extreme, when the weather is nice for effective heat pumping , I set it at 40 minutes so the AUX only comes on when there is a big temperature difference to overcome. At the other, when it's humid, around 30, wet snow kind of conditions I set it at 5 minutes.

The third stage is also settable from 5 to 40 minute delay; In the very worst heat pumping conditions, I set both the second and third stage delays to 5 minutes, pay the extra, and be comfortable.

Also, I did have good luck phoning Robertshaw tech support with a couple similar mode of operation questions and they were helpful.
 
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