Results 1 to 10 of 10
  1. #1
    Join Date
    Feb 2008
    Posts
    4

    Heat Pump Controls frustration

    I was glad to find this forum. I hope someone can give some help/advice.
    It's hard to know where to start but I will try to get to my most important issue.

    A local HVAC contractor installed a new Bryant Heat Pump & Fan/Coil unit in my house a little over 2 years ago. I have had multiple issues with this unit, most of them related to installation, but I won't go into those right now. I just wanted to mention that so you could better understand my frustration. About a month ago I noticed one morning that the unit was not running and that the thermostat had no power. I discovered that the 5 amp fuse on the fan control board was blown. I replaced the fuse and got the unit running again. It ran for 2 weeks with no issues until the fuse blew again.
    (Just so you know, I have worked with electrical controls
    and industrial automation for almost 18 years and have done a lot of troubleshooting. While my unit was still under warranty I did not attempt to do any type of troubleshooting even though there were some controls related issues during the first few months. Also I do
    not do anything related to refrigerant. That's not my area of
    expertise.) Anyway, with the fuse blowing a second time I knew there
    was some issue going on. I thought the fuse blowing might be related to a failed rectifier/relay that controls the auxiliary heat.
    I disconnected the wires going to the relay coil and the fuse has not blown since. The reason I thought the relay had failed, possibly in the closed/on position was that my aux. heat units were cycling on and off even though the fan was not running. The elements would come on and then turn off when the high temp limit switches would open. What I then did was disconnect the power wire from the relay to the aux. units and reconnected the relay coil wires. Still no blown fuse again. One of the things that really has me puzzled is that one of the aux. heat units is wired to the normally closed contacts of the fan relay, so whenever the fan is not running power is going to this unit. It comes on and and cuts off when the limit switch opens. I checked the wiring diagram and this was the correct wiring. Why would the aux. heat need to come on when the unit is not running?

    Anyway, I am attaching a couple of pictures to show what I think may have contributed to my problem. Even if this didn't cause the problem it still is a poor design. Seems there should be some type of barrier between the heat terminals and the foil on the insulation. Thanks for your help.
    Attached Images Attached Images   
    Last edited by rta53; 03-03-2008 at 10:37 AM.

  2. #2
    Join Date
    May 2004
    Posts
    1,462
    Your thumbnails are not displaying. The strip heat should not be on when the fan is not running or the thermostat is not calling. You are mistaken about the NC contacts of the fan relay and how that works. Yes it is wired there but it does not cause the heaters to energize, it has another function involving the fan operation.

    There is no need for a barrier as you call it. There are millions of these units installed with no problem and it is a UL approved design. If the insulation is making contact in this area it is because it has either been pulled down improperly or there has been moisture in this area that caused the glue to dissolve and weighted the insulation down.
    If all else fails....Try reading the directions!

    Tell it like it is and let the chips fall where they may.

    Any views or opinions stated here are strictly my own.


  3. #3
    Join Date
    Feb 2007
    Location
    18951
    Posts
    1,593
    As plain said, the heat strips should not come on without the blower running. You have a malfunction that could either burn out the elements and/or cause a fire. You are most likely reading the schematic wrong, and should call someone to look at it.

  4. #4
    Join Date
    Feb 2008
    Posts
    4
    Quote Originally Posted by plain spoken View Post
    Your thumbnails are not displaying. The strip heat should not be on when the fan is not running or the thermostat is not calling. You are mistaken about the NC contacts of the fan relay and how that works. Yes it is wired there but it does not cause the heaters to energize, it has another function involving the fan operation.

    There is no need for a barrier as you call it. There are millions of these units installed with no problem and it is a UL approved design. If the insulation is making contact in this area it is because it has either been pulled down improperly or there has been moisture in this area that caused the glue to dissolve and weighted the insulation down.
    Ok I reloaded the images. Hopefully they will display this time. After looking at the schematic again I realize I was mistaken. The purpose of the wire going to the NC contacts on the fan board is to energize the fan when the aux heat unit is energized. However I do know that the aux heat comes on and the fan does not. That is why I disconnected the aux heat power wires. In my previous post I mentioned having several issues with the initial installation of this unit. One of the issues was that the installer had the thermostat wired so that the aux. heat always came on when the unit was running. I had expected my power bill to be lower with the new heat pump but instead it was actually higher. I knew this could be attributed to a colder winter so I didn't think it was a wiring issue. This wasn't discovered until the spring (the unit was installed in January) when a technician came out to troubleshoot why the outside unit would run at times when the blower would not. He ended up having to replace the fan control board. Perhaps the thermostat is still wired incorrectly and may explain why the aux. comes on even though the blower is off.

    As for the insulation. It has not been wet. It may have been pulled down. I really don't have an explanation. I sent the same pictures to the installer but he did not respond as to why this happened.

  5. #5
    Join Date
    Mar 2008
    Posts
    10
    One side of the electric heat is always energized, but the other side is not energized until a call for electric heat. The insulation looks as if it fell. It is not necessary to have it in the control area. You can remove it or place some tape around the open terminal off the high temp sensor. It sounds as if the t-stat is wired incorrectly. The aux heat should only come on if the temp call is too high for the heat pump or a call for emerg. heat.

  6. #6
    Join Date
    Feb 2007
    Location
    18951
    Posts
    1,593
    There are at least 3 things I can think of off the top of my head that could be wrong with the heat strips coming on without the fan. They may or may not be related to your low voltage fuse blowing. Either way, you need someone familiar with HVAC systems to check it.

  7. #7
    Join Date
    May 2004
    Posts
    1,462
    Quote Originally Posted by red73 View Post
    One side of the electric heat is always energized, but the other side is not energized until a call for electric heat. The insulation looks as if it fell. It is not necessary to have it in the control area. You can remove it or place some tape around the open terminal off the high temp sensor. It sounds as if the t-stat is wired incorrectly. The aux heat should only come on if the temp call is too high for the heat pump or a call for emerg. heat.
    The insulation is needed in that area to keep the area from sweating. There will always be some air leakage into this area and if the unit is installed in an enviorment where the surrounding air is warmer and contains moisture it will condensate when coming into contact with the cooler metal surfaces, primarily during the cooling mode.
    If all else fails....Try reading the directions!

    Tell it like it is and let the chips fall where they may.

    Any views or opinions stated here are strictly my own.


  8. #8
    Join Date
    Feb 2008
    Posts
    4
    Quote Originally Posted by plain spoken View Post
    The insulation is needed in that area to keep the area from sweating. There will always be some air leakage into this area and if the unit is installed in an environment where the surrounding air is warmer and contains moisture it will condensate when coming into contact with the cooler metal surfaces, primarily during the cooling mode.
    Is there a particular type of adhesive I could use to glue the insulation back to the top? I thought about installing a piece of sheet metal as a bracket to hold the insulation up off the heater terminals. I have attached a couple more pictures to show much the insulation has come loose.
    Attached Images Attached Images   

  9. #9
    Join Date
    May 2004
    Posts
    1,462
    Your first pictures still do not work. The last ones show some pretty rough handling at installation, especially at the electrical connection. This could also be the cause of the upper insulation being down, pulled down during installation. 3M makes a spray adhesive that can be purchased at home improvement centers that works pretty good.
    If all else fails....Try reading the directions!

    Tell it like it is and let the chips fall where they may.

    Any views or opinions stated here are strictly my own.


  10. #10
    Join Date
    Feb 2008
    Posts
    4
    I can open up both sets of pictures from the forum. Not sure why they are not working for you. Maybe if you reload the page. Just a thought. Thanks for the advice about the adhesive.

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