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  1. #27
    Join Date
    Nov 2004
    Posts
    2,927
    [QUOTE]Originally posted by georgiaguy
    I can not get the tech to explain to me why it would be blowing air before the heat pump turns on. Is this normal operation?

    My first guess was that a saftey in the outdoor unit is opening-anti cycle timer or pressure switches. But my knowlege is fairly limited to the less sofisticated systems...thr ones that i can see, hear, touch...

    Could I be wrong, and the heat pump compressor is on, but the heat pump fan is not? Could it be a redundant delay? If so, is it unavoidable or can it be corrected?

    If you can get to the furnace then put your hand on the refrigerant lines.If its in defrost and compressor is pumping then the large line should be cold.

    My final question, is there a good reason for not turning on the stat option that automatically flips the system from heat to cool or vice versa, as the case may be?

    I dont like auto changeover because it is wasteful.But I dont dont think it is relevant here.

  2. #28
    Join Date
    Feb 2006
    Posts
    103
    Okay now I've experienced a similar problem in the cool mode. It's 80 degrees outside I walk inside the stat shows it's 77 degrees but the set temp is 74. The stat says "Cool On" and "Auto" fan. The blower is blowing but the compressor is off. I take a shower, come out of the shower and no change. My wife is hot so she drops the stat to 72. No change. "Cool On" and "Auto" fan still shown on stat but no compressor action. I'm getting annoyed, so I decide to break out the installation manual and check the set up. The tech set the cycles per hour to 6 for both the heat and cool settings. I changed them back to 3 each. The delay was set to 5. I see you can turn if off (the tech said it wasn't possible) so I give it a try and turn it off. I also turn on the "Extended Fan On Time Heat" and "Extended Fan On Time Cool". They seem like good functions to me (although they could add a confusing element to my experiment). I then turn the system on and bingo the compressor turns on. Stat reaches set point, compressor kicks off, but fan runs for at least 90 secs. I wait a few minutes, and drop the stat. The stat kicks into "Cool On" and the compressor kicks on about 30 secs later. Compressor runs for awhile then it turns off before hitting the set point, the "Cool On" stays on and the blower stays on. I suspect the system is trying to avoid "over shooting" the set point, but I'm not sure. It's clear to me it's going to "under shoot" the set point. As I'm typing this the compressor has kicked on again (it must have been off for at least 5-10 minutes, the blower never turned off. Hopefully it won't turn off until the set point is reached. Nope, the compressor has turned off again. Damn this system confuses me.

  3. #29

    Vision Pro

    I have put in a contract for a single speed compressor Trane XL14i heat pump to be added to my 2 stage XV80 furnace. Trane dealer has VisionPro (VP) included in the bid. Because he is giving me what I consider to be a "good price", I probably plan to mess with or get a different thermostat later.

    He did say he plans to configure the VP to use gas at 39 degrees or lower. I also believe he said I will still need a "jumper" in my 2 stage furnace because VP can only treat the furnace as 1 stage.

    When the furnace has a jumper, it will flip to 2nd stage heat after 10 minutes (regardless of what t-stat is used I know this for sure - I saw it in Trane literature). I hope I don't have blower noise. Well, if it saves on my utilities, I'll get over it ! That's my motto (for now).


  4. #30
    Join Date
    Mar 2004
    Posts
    1,042
    xv80satisfiedcustomer: The VisionPro is by no means a cheap thermostat. It comes highly regarded and is very popular. Contractors like to quote it because it's impressive and customers like it. That's almost the only way that a customer interacts with their HVAC equipment, so specifying an ooh-wow thermostat often makes the customer feel like they're getting something nice for their money (the furnace, heat pump, air handler, etc., tend to be invisible, and few customers can recognize the difference between cheap equipment and nice equipment).

    The only drawbacks to the VisionPro that keep it from being the gold standard are that the just that their dual fuel control and humidity control is a little simplistic. Many people are willing to overlook those two minor drawbacks and already consider it the gold standard. In practice it probably is the gold standard so long as your particular application doesn't depend on those features.

    You may want to ask your contractor about switching to something different that can properly control those furnace stages. If the alternative isn't some other touch screen, they may be happy to do it for the same price. The VisionPro is an awfully nice (and expensive) stat to buy and install just for temporary stopgap "until I get something better" use.

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