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  1. #1

    Question Auxiliary Heat on 80-90% of the time!? (Carrier Infinity)

    Background
    We built a new house in 2005-2006. Early 2006 we had a Carrier Infinity heat pump installed. I believe it was 17 SEER with 9 HSPF. The cost in the summer isn’t bad at all, but the cost in the winter is killing us. The auxiliary heat is staying on about 80-90% of the time. We are using the Carrier programmable thermostat (66 at night, 70 in morning, 66 when we leave, 70 in the evening). After some research here it looks like the 4 degree difference is making the aux heat come on. The part that gets me worse is that the aux heat comes on to even keep it a 70. It’s been mid 50s and sometimes in the 60s outside and the aux heat comes on to keep it at 70. From some previous posts I read, I probably need to call the tech, but that brings up another problem. The HVAC contractor is one of the contractors I don’t recommend when I talk to other people thinking about building. For one thing, one of them stole some copper pipe from the house when they were installing the system (there were also several other problems during the install). I called last winter (06-07) and told them about the aux heat problem and the tech told me “that’s normal”. I would probably call someone else, but I bought a 10 year parts and labor warranty from them. I’d like to have an idea about how it should be setup before I call them again.

    1. At what temperature should a lockout be set, to keep the aux heat from coming on?
    2. Should I just set the temp of the house to 70 and not use the programmable part of the thermostat (that don’t seem right though)?
    3. Is there a way to keep the aux heat from coming on in the 4 degree increase?
    4. Is there any other information I need to know before calling?


    Many, many thanks for any help!!!
    Last edited by kmcconnell; 01-07-2008 at 03:33 PM. Reason: Modified title

  2. #2
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,916
    Unless it is rather mild, a heat pump will need help warming a house 4°. I don't care how smart the thermostat is (I know many will say their smart stat can do it) if the house temp is near the balance point, there may not be enough excess capacity for a warmup. The balance point is the outdoor temp where the heat loss of the house equals the heat output of the heat pump. At that temp, often in the upper 20s, the pump will maintain but not have enough extra capacity to warmup the house. Remember that you are not only warming the air but every surface in the house, walls, carpet, furniture. As the air warms up, the cold surfaces grab the heat which is why warmups may take a while.

    The Infinity gurus will tell you how to lock out aux. You'll have to decide if a setback in cold weather is wise. I don't do it.

  3. #3
    Join Date
    Dec 2006
    Location
    Fayetteville,Arkansas
    Posts
    1,427
    You want your Infinity Control to lock out the aux. heat at any temp above

    30 degrees. You essentialy have 4 stages of heat. 1st stage compressor

    and 2nd stage compressor. You also have 2 stages of electric heat.

    When your program calls for a 4 degree rise in temp it will stage on at

    least 5 kw of electric heat if you don't have a temp lock out on it.

    If it is running aux heat while maintaining 70 degrees then you likely have a

    problem. When the room temp reaches 68-69 the aux. heat should stage

    off.
    If you choose not to decide you still have made a choice.

  4. #4
    Join Date
    Feb 2004
    Posts
    451
    Quote Originally Posted by kmcconnell View Post
    I would probably call someone else, but I bought a 10 year parts and labor warranty from them. I’d like to have an idea about how it should be setup before I call them again.
    Usually the 10 year parts and labor warranties are through the manufacturer. You could check in your area a different company that is an authorized dealer and see if they will cover it.
    Before you criticize someone, walk a mile in their shoes...that way you are a mile from them and have their shoes

  5. #5
    Hetrola -
    Seems like if it was from the manufacturer I would have had to fill out some paperwork. I don't remember filling out any additional paperwork about warranties.

    There is one guy there that I sort of trust, but I would still want to be there watching him while he checked the unit out.

    hvaclogic - Is locking out the aux heat above 30 a good pratice? This is our only heat source currently. I'm thinking of getting a vent free fireplace to supplement the heat when we need it. If I did do that would I be able to use the programmable therm. the way I have it set?

  6. #6
    Join Date
    Feb 2004
    Posts
    451
    Quote Originally Posted by kmcconnell View Post
    Hetrola -
    Seems like if it was from the manufacturer I would have had to fill out some paperwork. I don't remember filling out any additional paperwork about warranties.

    There is one guy there that I sort of trust, but I would still want to be there watching him while he checked the unit out.

    hvaclogic - Is locking out the aux heat above 30 a good pratice? This is our only heat source currently. I'm thinking of getting a vent free fireplace to supplement the heat when we need it. If I did do that would I be able to use the programmable therm. the way I have it set?
    call up the current company and have them mail you over your information on the 10 yr P&L. They should have some paperwork on it or chances are you really dont have one even tho you paid for it.
    Before you criticize someone, walk a mile in their shoes...that way you are a mile from them and have their shoes

  7. #7
    Join Date
    Dec 2006
    Location
    Fayetteville,Arkansas
    Posts
    1,427
    Quote Originally Posted by kmcconnell View Post
    Hetrola -
    Seems like if it was from the manufacturer I would have had to fill out some paperwork. I don't remember filling out any additional paperwork about warranties.

    There is one guy there that I sort of trust, but I would still want to be there watching him while he checked the unit out.

    hvaclogic - Is locking out the aux heat above 30 a good pratice? This is our only heat source currently. I'm thinking of getting a vent free fireplace to supplement the heat when we need it. If I did do that would I be able to use the programmable therm. the way I have it set?
    I set up all of our Infinity systems to lock out the electric heat at 30.

    Your heat pump if sized properly will make plenty of heat to warm your home

    at temps above 30.

    As far as the extended warranty goes, the installing contractor owns that

    warranty and is required to preform the warranty work. However, if you are

    are not satisfied with the installing contractor you may contact Carrier and

    they will transfer your warranty to another dealer in your area.
    If you choose not to decide you still have made a choice.

  8. #8
    OK, for now I've set the temp to 69 except for the evening and its at 70. Besides having the lockout set at 30 is there anything else that he should check or set while he is here. Thanks again.

  9. #9
    Join Date
    Mar 2006
    Location
    The South
    Posts
    2,143
    kmcconnell

    I definitely would have aux lock-out around 32 degrees. Watch installer to learn how he does this so you can adust up or down as needed.

    Your title bothers me. It indicates that your Infinity HP system is either undersized or there are installation/mechanical issues with your HP in heating mode. IF AC cooling this past summer was OK on both comfort and energy consumption, then your installer should look at the latter. Under normal circumstances, no way aux heat strips should operate 80% of the time unless you are in hard cold snap. Do you mind stating size of your HP, size of your home, and area/location where you live?

    IMO

  10. #10
    The house is about 3000 sq ft and I've actually got two 4 ton units, one for upstairs and one for downstairs. I live in Virginia, but near the border with Tennessee. I’m going to guess that the average low will be around 20-35 at night. We do get some single digit cold snaps, but that is pretty rare. We are actually going to be near 70 today, that’s rare also.

    If he locks out the aux heat at 32, will it still be able to come on during defrost mode?

  11. #11
    Join Date
    Mar 2006
    Location
    The South
    Posts
    2,143
    kmcconnell

    8 tons for 3000 sq ft? humm...

    do you have high ceilings, lots of windows, poor insulation?

    was a load calculation performed?

    you have the Carrier Infinity controller on each system?

    As far as defrost goes, installer can set heat strips to come on in defrost mode...

    My first question would be why aux is activated with so many BTUs. Something is not correct here!

    IMO

  12. #12
    The upstairs unit was oversized to account for a bonus room and the connecting room which is currently not finished. They went ahead and sized for it and put in a damper to turn off the air. (This is one thing that I need to have him look at. We've tried changing the damper and we can't get any air movement into the bonus room.)

    Anyway, I actually had 7 estimates (5 heat pumps, 2 geothermal). I got to see 3 or 4 of the load calc and they were nearly the same in their recommendations. We also have a two story family room with two 60" fans installed 7' down from ceiling. We run these 24/7 and they do a good job circulating the air. Both units are the same; Carrier Infinity with the Infinity controller. We do have several windows also, but they were some of the best windows we could get locally at that time. They seem to be insulated pretty good. Even on a single digit temp day I could stand inches from the window and not feel any coolness coming from the window. We were the GC and we did our best to seal the house as best as we could during the building process, much more so than any other houses I’ve watched being built around here.

  13. #13
    Join Date
    Dec 2006
    Location
    Middle Tennessee
    Posts
    11,347

    *

    set your recovery to bring temp up 2 degrees at a time in order to stop auxilllary from kicking in!



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