Heat pump and strip heat questions
Page 1 of 3 123 LastLast
Results 1 to 13 of 29
  1. #1
    Join Date
    Oct 2011
    Location
    Birmingham, AL
    Posts
    32

    Question Heat pump and strip heat questions

    I just had two 2.5 ton Weather King heat pumps and air handlers with electrical heat strips installed in my two story home. The thermostat installed has four options...Off, Cool, Heat, and Emergency Heat. I understand when the outside temp. dips low enough, the outside coil will freeze up and reverse to cool mode to pump heat outside to thaw the coil. The heat strips are then used so the home will still be slightly heated instead of cooled. I also know the heat strips are designed to be supplemental to the heat pumps when the temp. is low enough that the heat pumps can't heat enough on their own. I also know the strips are expensive to run.

    My installation contractor told me that I always needed to set my thermostat to emergency heat if the temp. was going to drop below 40 degrees I believe. From what I've read, emergency heat only uses heat strips but auxiliary heat uses both the heat pump and strips at the same time. So does that mean since I don't have an auxiliary setting on my thermostat that my system will not work in auxiliary mode and only heat strips are being burned all night in emergency mode?? Or is the regular "heat" setting actually auxiliary and only uses the strips when needed?

    I didn't realize it was going to drop below 40 last night so I woke up some time with my outside unit(s) cutting on for a short time then shutting off so I assume they were freezing up. I then quickly switch both thermostats to emergency heat. The heat pumps wouldn't have been damaged, would they? Is it not smart enough to know it's freezing up and turn the heat strips on?

    I've never known of a system where I've had to be so constantly aware of the outside temperature and switch the emergency heat on and off, though most of my other systems have been all gas or gas piggyback.

    Other than keeping both floors the same temp, installing a programmable thermostat and/or an outdoor thermostat in the heat pump to keep the heat strips from coming on above a certain temperature, are there any other options? Are those expensive options?

    I live in central Alabama if that helps.

  2. #2
    Join Date
    Jun 2006
    Location
    Richmond, VA
    Posts
    2,812
    You are correct in the operation of heatpumps.

    Set the thermostat on your temp and let them run.
    Give a man a fish, he will eat for a day. Teach a man to fish, he will eat for a lifetime.

    Give a man a capacitor, doesn't know what to do. Teach a man to install it, now he knows everything.

  3. #3
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,058
    Quote Originally Posted by sqwerl View Post
    I just had two 2.5 ton Weather King heat pumps and air handlers with electrical heat strips installed in my two story home. The thermostat installed has four options...Off, Cool, Heat, and Emergency Heat. I understand when the outside temp. dips low enough, the outside coil will freeze up and reverse to cool mode to pump heat outside to thaw the coil. The heat strips are then used so the home will still be slightly heated instead of cooled. I also know the heat strips are designed to be supplemental to the heat pumps when the temp. is low enough that the heat pumps can't heat enough on their own. I also know the strips are expensive to run.

    My installation contractor told me that I always needed to set my thermostat to emergency heat if the temp. was going to drop below 40 degrees I believe. From what I've read, emergency heat only uses heat strips but auxiliary heat uses both the heat pump and strips at the same time. So does that mean since I don't have an auxiliary setting on my thermostat that my system will not work in auxiliary mode and only heat strips are being burned all night in emergency mode?? Or is the regular "heat" setting actually auxiliary and only uses the strips when needed?

    I didn't realize it was going to drop below 40 last night so I woke up some time with my outside unit(s) cutting on for a short time then shutting off so I assume they were freezing up. I then quickly switch both thermostats to emergency heat. The heat pumps wouldn't have been damaged, would they? Is it not smart enough to know it's freezing up and turn the heat strips on?

    I've never known of a system where I've had to be so constantly aware of the outside temperature and switch the emergency heat on and off, though most of my other systems have been all gas or gas piggyback.

    Other than keeping both floors the same temp, installing a programmable thermostat and/or an outdoor thermostat in the heat pump to keep the heat strips from coming on above a certain temperature, are there any other options? Are those expensive options?

    I live in central Alabama if that helps.
    depending on what Tstats you have will have a big influence on what happens.

    You do not need to turn off and use emergency heat under most circumstances.

  4. #4
    Join Date
    Aug 2011
    Location
    Eastern Shore, MD
    Posts
    798
    you do not need to turn it to emergency heat below 40 degrees. below 17 degrees it makes sense efficiency wise (in most cases).

  5. #5
    Join Date
    Oct 2011
    Location
    Birmingham, AL
    Posts
    32
    The temp. dipped to the mid to low thirties last night and I woke up with one of my heat pumps turning on and off rapidly. The contractor warned me of this and I'll have to double check with him because it may have been below 30 degrees he said I'd have this problem if I didn't switch to emergency heat.

    So I don't understand what the problem could be.

  6. #6
    Join Date
    Aug 2011
    Location
    Eastern Shore, MD
    Posts
    798
    Quote Originally Posted by sqwerl View Post
    The temp. dipped to the mid to low thirties last night and I woke up with one of my heat pumps turning on and off rapidly. The contractor warned me of this and I'll have to double check with him because it may have been below 30 degrees he said I'd have this problem if I didn't switch to emergency heat.

    So I don't understand what the problem could be.
    short cycling is not a factory design...sounds like something is wrong.

  7. #7
    Join Date
    Oct 2011
    Location
    Birmingham, AL
    Posts
    32
    Could the unit be oversized?

  8. #8
    Join Date
    Aug 2011
    Location
    Eastern Shore, MD
    Posts
    798
    doubtful at 2.5T to the point it would cause short cycling. Also, most digital tstats have compressor protection built in. Could be tripping high or low pressure switches in the refrigerant circuit to cause that.

  9. #9
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,597
    Something not right with the heat pump or installation. here, we don't lock out the heat pump unless its goes below -10F.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  10. #10
    Join Date
    Oct 2011
    Location
    Birmingham, AL
    Posts
    32
    Just to make myself clear I did not have the thermostat on emergency heat when I perceived it to be short cycling. I wonder why the contractor would tell me to put it on emergency heat when it isn't that cold?

  11. #11
    Join Date
    Oct 2011
    Location
    Birmingham, AL
    Posts
    32
    Just spoke with the contractor and I was a little mistaken on when he recommended I cut the emergency heat on. His suggestion was to only cut e. heat on days that it would be below 30 or 40 degrees most of the day. This would prevent the heat pump from going into constant freeze/thaw cycles.

    He said what I probably heard last night, which I though was short cycling, was the unit going into defrost mode and said it may make some funny noises and the fan may cut on and off a few times.

    He's never heard of a unit short cycling in winter just in summer cooling.

  12. #12
    Join Date
    Sep 2009
    Location
    Arnold mo
    Posts
    3,909
    Quote Originally Posted by Gross View Post
    doubtful at 2.5T to the point it would cause short cycling. Also, most digital tstats have compressor protection built in. Could be tripping high or low pressure switches in the refrigerant circuit to cause that.
    The digital t-stats I've installed have the compressor protection, but you have to go into the programming to activate that option.
    An answer without a question is meaningless.
    Information without understanding is useless.
    You can lead a horse to water............
    http://www.mohomeenergyaudits.com

  13. #13
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,829
    Heat pumps are meant to run but they don't do much in bitter weather. We tell people if they are tired of the 24 hour operation when it gets down to the teens and colder, go to emergency heat. Otherwise, units with demand defrost, like your unit, only defrost when needed so they aren't wasting juice hourly on unneeded defrosts. Do what's comfy for you but leave it on well below 40 or you'll be paying way too much for heat.

Page 1 of 3 123 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event