Return to the Heating & Air Conditioning Forum | Post a Follow-Up

Will thermostat show heat pump in defrost mode

Posted by richard904 (My Page) on
Thu, Mar 14, 13 at 14:16

We have a Trane XL16i with a Honeywell VisionPRO IAQ thermostat. When the heat pump is on, the thermostat shows Heat On mode, but even when the heat pump is defrosting the Aux Heat On does not show. When there is a several degree temperature variation between requested heat and actual heat it does show the Aux Heat On. Is this the expected information in the defrost mode?

Our old system with its very simple thermostat would show the aux heat on light when the system was in defrost mode.

Follow-Up Postings:

RE: Will thermostat show heat pump in defrost mode

Here is the installation manual. I am not sure if it is exactly the model you have. There is no mention of auxiliary heat being displayed during the defrost cycle.

Here is a link that might be useful: Honeywell Visionpro IAQ thermostat

RE: Will thermostat show heat pump in defrost mode

I looked at the link you gave, and at all the manuals I had, and indeed there is no mention of this. I presume then the heat pump communicates directly with the air handler to turn on auxiliary heat through a "back channel" so to speak, and the thermostat is unaware of this or does not care.

RE: Will thermostat show heat pump in defrost mode

Richard, you are correct. The heat pump controls auxiliary heat signal to indoor air handler. When the thermostat calls for aux heat, then it will display on the screen itself.

This post was edited by ryanhughes on Sat, Mar 16, 13 at 11:53

RE: Will thermostat show heat pump in defrost mode

Mine does not show when the unit is in defrost but I plan to use some spare thermostat wires and send a signal up to some leds behind the stat that will signal defrost mode and aux mode and cast light behind the stat.

It is rarely in defrost unless we are having some sort of moisture event close to or below freezing which is why demand defrost is awesome.

RE: Will thermostat show heat pump in defrost mode

I have a carrier heat pump with a carrier oil furnace for Aux Heat... a Carrier Edge Thermostat.

When HP is in defrost mode, the thermostat shows "Aux Heat" as heating mode.

 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!

Return to the Heating & Air Conditioning Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.

Learn more about in-text links on this page here