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  1. #1
    Join Date
    Jun 2004
    Posts
    37

    Is this a Thermostat issue ?

    Hi all -

    5 year old AC / Heat Pump , unknown age of the Honeywell Thermostat ( can't find a model number on it anywhere). I was told the unit is a 5 ton. House is about 2200 sf.

    I'm concerned about the short periods between cycles. If the thermostat is showing a temp of 68* and I bump it up to 70* the unit will run and produce very warm air. Once it reaches the set temp it runs for about 10 minutes but blows air that is not as warm and once it shuts off, it cycles back on after about 5 minutes.

    I hope this makes sense. I find myself bumping the temp up a couple degrees, letting it run to get to that temp and then bumping it down a couple degrees so it does not cycle on and off so much and blow cooler air. It's like it is trying to hold the temp exactly as set with no variation.

    Do I need to cal someone out to install a newer Thermostat ?

  2. #2
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,302
    If it's a programmable thermostat, it may have a cycles per hour adjustment, which may need to be reduced to lengthen the off time of your system between calls for heat.

    The reason the air was warmer when you raised the thermostat setpoint a few degrees is that the system will likely bring on the auxiliary heat to help raise the house temperature more quickly. Once it is attained and the system then cycles to hold setpoint, the supply air is cooler because only the heat pump is running to provide the heat.

    Many people object to heat pump air as being too cool. Many times the problem isn't the air temperature, but the fact that the supply air registers are chosen and/or aimed improperly. You should not feel any draft at all from these registers if they are correctly aimed. The cheap stamped steel registers are worthless (I am assuming your registers are in the ceiling or high on the walls)...curved blade registers are much better and can be set to throw the air out into the room, not onto you.

  3. #3
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,058
    Quote Originally Posted by phillbo View Post
    Hi all -

    5 year old AC / Heat Pump , unknown age of the Honeywell Thermostat ( can't find a model number on it anywhere). I was told the unit is a 5 ton. House is about 2200 sf.

    I'm concerned about the short periods between cycles. If the thermostat is showing a temp of 68* and I bump it up to 70* the unit will run and produce very warm air. Once it reaches the set temp it runs for about 10 minutes but blows air that is not as warm and once it shuts off, it cycles back on after about 5 minutes.

    I hope this makes sense. I find myself bumping the temp up a couple degrees, letting it run to get to that temp and then bumping it down a couple degrees so it does not cycle on and off so much and blow cooler air. It's like it is trying to hold the temp exactly as set with no variation.

    Do I need to cal someone out to install a newer Thermostat ?
    Can you post a picture and we can tell you what Tstat you have?

  4. #4
    Join Date
    Jan 2003
    Location
    Olathe Kansas
    Posts
    246
    Often people blame the stat for short cycles but usually it is not the problem. If it just started acting up for no reason I doubt it is the thermostat. Hard to tell from here. Could be a number of things. Good luck.

  5. #5
    Join Date
    Jun 2004
    Posts
    37
    It's an older Honeywell.
    Attached Images Attached Images  

  6. #6
    Join Date
    Jan 2007
    Location
    bowie md
    Posts
    116
    This is not a heat pump thermastat

  7. #7
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,709
    could bumping it up a few degrees be bringing on aux heat ????????

  8. #8
    Join Date
    Jun 2007
    Location
    Pigeon Forge, TN
    Posts
    295
    no this stat is single stage

  9. #9
    Join Date
    Jan 2007
    Location
    bowie md
    Posts
    116
    It is possable that cool air is coming from wall . Is hole for t-stat wires sealed?

  10. #10
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,773
    That could be an early Chronotherm lll, 2 stage heat, 2 stage cool. But its not for heat pumps, its for conventional.

    If its single stage, then its bringing on strips.

    Have a service company come out and check oout your system. Its probaly been a while since you had it sericed.
    Ask for them to install a new HEAT PUMP thermostat while they are there.
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  11. #11
    Join Date
    Jun 2007
    Location
    Pigeon Forge, TN
    Posts
    295

    are you sure its heat pump?

    When you put it in heat does the outside unit run?

    This single stage thermostat can run a heat pump in single stage (no aux) or electric strips but not both so if you have both you have the wrong thermostat. Anotherwords it will only use the strips or only use the heat pump. If you have both you need a heatpump stat with aux heat.

  12. #12
    Join Date
    Mar 2004
    Location
    Grottoes VA
    Posts
    5,856
    That t-stat is a lowes special. I've only seen the RTH models with the selector switch.
    Karst means cave. So, I search for caves.

  13. #13
    Join Date
    Jun 2004
    Posts
    37
    Quote Originally Posted by JumpSteady View Post
    When you put it in heat does the outside unit run?

    This single stage thermostat can run a heat pump in single stage (no aux) or electric strips but not both so if you have both you have the wrong thermostat. Anotherwords it will only use the strips or only use the heat pump. If you have both you need a heatpump stat with aux heat.

    Yes, I can her the compressor run. It runs for a couple secs before the fan kicks in (just like when on AC for cooling ). I have no clue if the unit has aux heat strips... I'm in Arizona so not sure if they are needed.

    What would explain the difference in the air temp out the vents ?

    I'll get a tech out to take a look ... Hey, can the blower speed be turned down? It sounds like a turbo jet taking off and blows like a mofo ..

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