When does your Aux Heat kick on?

Discussion in 'General Discussions' started by vortrex, Dec 10, 2018.

  1. ChrisJ

    ChrisJ Active Member Forum Leader

    Is it the 1st floor zone that calls for aux mostly or both?
     
  2. vortrex

    vortrex Member

    The 1st floor would be the only one calling for aux unless it was an unusual situation where the heat was off for some time and the whole house got cold.

    Interesting, I just switched it from 70/25 to 70/45 and zone 1 changed from stage 2 to stage 1 heating (zone 2 still off). Wonder why it would stage down if I decreased the size % of zone 1? It's pretty warm out now, says 38F. Tonight it will be mid 20's and a better test of various settings.

    I also have the staging settings to consider, which are completely confusing to me after reading the docs. Normal, Quicker, Faster1, Faster2. Anyone with experience with these? It's set for Faster1 now.
     
  3. vortrex

    vortrex Member

    Ended up getting warm for several days so I was unable to test. Last night it dropped to lower mid 20's over night and with the Aux differential set high (essentially turned off) the geo could not keep up. It was 67F when I woke up with the stat set at 70F. It sure seems like if I could unleash H11-H12 that would help a lot without having to always go to Aux at 4.5x the cost of H10. Anyone have an idea how to get it to use H11-H12?
     
  4. nc73

    nc73 Member Forum Leader

    That doesn't sound right. With those temps, it should keep up and go to the proper stage. Did you contact your installer? Something is not right of course.
     
  5. vortrex

    vortrex Member

    Yes, I've mentioned this several times to them over the past few years since it was installed with no success in getting anything done. I'd like to try and resolve this myself at this point. Also, there's been no software update to this since it's been installed. I have to wonder if there's a newer release out now which may improve things?
     
  6. nc73

    nc73 Member Forum Leader

    Yeah I would insist they fix it. I'm not use to the high tech thermostats and fancy heat pumps. I will keep my 2 stage heat pump that works as intended. How about contact the manufacturer? I would disable the strips at the heat pump, dip switches or whatever and see if it goes to the higher stages.
     
  7. vortrex

    vortrex Member

    I was watching the stat right when it went from H10 to Aux. I usually am not watching it because I can tell by the noise when Aux kicks on. It went from H10, to very briefly H11, and then to H12/Aux. It seems like H11 is nothing more than a transition to Aux, which is actually H12?

    I don't necessarily think there is anything wrong with the system. I do think it is likely undersized given the home design. The thing is, since it was installed I've made many big improvements to the air sealing and insulation. So, when this 4 ton was spec'd the thermal condition of the house was far worse than it is now. As I mentioned, I still have a couple projects left to do. I will get these done before next winter. At that point if the 4 ton cannot keep up I will demand something be done about it.

    I think having the Aux heat come on in the mid teens would be reasonable. As it is with it kicking on in the mid 20's it runs for multiple hours essentially every day here in MI.
     
  8. ChrisJ

    ChrisJ Active Member Forum Leader

    I wonder if you could trick it into thinking it's only a single zone, since you say the 2nd floor doesn't run in heat mode.

    Do you do night time set backs? If you set it to hold a temp of 70* it might maintain temp without aux.
     
  9. vortrex

    vortrex Member

    I can try setting that zone off entirely, let me see if the stat will let me do that. The upstairs will run in heat mode, just not a lot.

    Not using any setbacks, constant 70F in both zones.
     
  10. nc73

    nc73 Member Forum Leader

    I know the pros like to size the unit with strip use to save money but the point of a heat pump is to use less electricity. This is why I slightly oversize so I never need strips. At least it works for me and I never have a high electric bill.
     
  11. vortrex

    vortrex Member

    I was able to shut off zone 2 from the advanced area of the stat and now zone 1 shows 100%. I'll leave it like this for 24hrs and see what happens.
     
  12. geoxne

    geoxne Active Member Forum Leader

    Waterfurnace recommends wiring an outside temp sensor to the LAS terminals on the IntelliZone2 relay panel to minimize use of Aux Heat. It is shipped with the panel. I assume your installer didn't use it. Once installed an outdoor temperature can be setup in Aux Heat Lockout that will prevent your electric heat from coming on above that. You can discover by trial and error which temperature setting works best for you. Maybe start with 20F based on the following.
    A house with cathedral ceilings and heat stratifying to the second floor can be very challenging to balance. The IntelliZone2 opens all zone dampers when Aux Heat is called. This would take even more heat away from the first floor and direct it to the second floor whether it needs it or not. Aux Heat Lockout will help you here also.

    You may also have to adjust your zone percentages when you get back in cooling season due to stratification.
     
  13. vortrex

    vortrex Member

    Correct, there was no outside temp sensor installed. That's unfortunate to know they skipped that step even though the device is provided. I will do this myself.

    Good info about the dampers with Aux on. I do adjust the zone %'s already when switching between seasons.

    Question - Is there really an H11-H12? My system will never go to that. It maxes out at H10, will briefly (a few seconds seconds) go to H11, and then direct to H12 Aux.
     
  14. geoxne

    geoxne Active Member Forum Leader

    Yes there are compressor speeds H11 & H12. Aux Heat can be energized anywhere between H9-H12. Anytime Aux Heat is energized the compressor will immediately increase to H12 unless there is a compressor lockout.
     
    Last edited: Dec 18, 2018
  15. vortrex

    vortrex Member

    Any ideas on why I max out at H10 under normal (no Aux) heating conditions? Someone earlier mentioned with two zones I might be locked out H11 and H12?
     
  16. geoxne

    geoxne Active Member Forum Leader

    I have no idea why. I'm sure some programmer wrote an algorithm and it made sense to them.
     
  17. nc73

    nc73 Member Forum Leader

    Call the manufacturer....
     
  18. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    WF has that kind of algorithm programmed into the Intellizone, namely that H11-12 will only come on with Aux heat. Makes no sense, but he the AHRI rating of the unit is in stage 9 or 10, and H11 and 12 is more than 100% of the rating. Essentially it has something to do with the performance ratings, the COP drops too much.
    So the 7 series is running at 100% capacity in stage 9.

    Certainly your unit should have been a 5 ton in my book, I was just trying to tell you earlier that there is no standard which regulates the amount of supplement heat designed into a geo system.
     
  19. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    See attached.

    4 ton in stage 12 has about 49 kbtu/h capacity, normally a 4 ton dual stage has about 38 kbtu/h heating capacity.

    Cooling is the key for the rating, as you can see there is more capacity than rated in stage 10-12.

    At the end of the day, you get more capacity with the 7 series then the model specification suggests, but it operates at a significant lower COP than the lower stages.

    Not an issue in reality, actually very beneficial, but the way the rating system works, it would not look good on paper.

    With the 7 series, we migrated from undersizing to sizing them for the whole load to cover all the peak events if possible.

    We would not have this discussion if you would have a 5 ton unit in your house.
     

    Attached Files:

  20. Jamie V.

    Jamie V. New Member

    In a older post there was a suggestion to set the differentials on the thermostat to:
    • 1st stage 1.0
    • 2nd stage 2.0
    • Aux heat 4.0
    I accessed this menu setting on my thermostat under the service hidden menu (hold the top left of the screen for 5sec).

    I live in MD so it isn't that cold but even when it gets down to 0°F my Aux heat doesn't kick on.
     

Share This Page