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  1. #1

    Prestige IAQ - low temp lock out for A/C ?

    Hi guys I have a Prestige thermostat with IAQ board and a RF out door temp sensor. I have just had a 3 ton A/C unit installed and all is working well. But I was told by the techs who installed the system to make sure I do not run the A/C compressor below 55'F or 13'C. Well I noticed last night the the system was kicking on the odd time with out over night outdoor temp being at 9'C. So I would like to set my Prestige to lock out the A/C compressor from starting if the temp is below 13'C to prevent damage. Problem is the techs have no idea how to program this controller and I had to assist them in just adding the cooling stage so the new system would work. Honeywell is telling me to contact the hvac company that did the work. So I am stuck in this loop of no help.


    I understand that you may not be able to tell me exactly how to do this my self, but if you know this can be done any maybe know what menu or setting to change and I can pass it along to the contractor when they come back out.


    Thanks for any help you guys can provide.
    Landon

  2. #2
    Join Date
    Jul 2007
    Location
    Delaware
    Posts
    3,824
    At the end of the set-up sheet, you can choose the temps the a/c & heat will operate in.

    For example: Cooling 65 to 90. Anything out of that range the system will not operate, you won't be able to set to 64.
    You can go to Honeywell and download the instructions.
    Always here

  3. #3
    Join Date
    Dec 2007
    Posts
    4,697
    The lock out described is for INDOOR temp not outdoor, is that what you were after?

    If you were talking about outdoor temp, then to my knowledge it has to be done with add on controls.
    The Food Stamp Program, administered by the U.S. Department of Agriculture, is proud to be distributing the greatest amount of free meals and stamps EVER.
    Meanwhile, the National Park Service, administered by the U.S. Department of the Interior, asks us to "Please Do Not Feed the Animals". Their stated reason for this policy "... the animals become dependent on handouts and will not learn to take care of themselves."
    from an excerpt by Paul Jacob in Sun City, AZ

  4. #4
    I am looking for a outdoor temp lockout. I will call our mechanical company that did the install and see what they have to say.

    Thanks for your input guys, you have been super helpful. I think I may have just had two installers out that day that were having a off day. Maybe I can talk to someone better at the company when I call today.

    Have a great week guys

  5. #5
    Join Date
    Jul 2007
    Location
    Delaware
    Posts
    3,824
    The indoor lock out is all you need. Why would you run the a/c when it is below 55? Is this a commercial application?
    Always here

  6. #6
    No it's a residential unit, it's our first central A/C unit, and now that we have it my wife has decided she likes the house at 20'C at night.

    We have a portable RF honeywell thermostat in our bedroom (2nd story) and it has been cooling off quite quickly out side the last couple days, but the house is holding heat still. Temp was set to 20'C and when I got up to let the dog out last night I seen it was below 13'C out and the A/C had kicked on for a few minutes. Not sure what kind of damage this could cause but I would like to avoid any damage at all if I can.

    Not sure how to proceed, I may call another mechanical company now. As after speaking today to the ones who installed it they spoke to me like I was a moron for even asking questions like this. It says right in the carrier manual not to run it below 12.78'C. So I want to make sure I we are not damaging it. We have only had it for 11 days now but I would like to take care of it as best we can.

    Thanks guys.

  7. #7
    Join Date
    Jan 2008
    Posts
    2,001
    68F (20C) is at the limit. When it's 55F (13C), the coil may freeze. Other controls can be added to make it operate in cooler temps.
    "Hey Lama, hey, how about a little something, you know, for the effort." And he says, "there won't be any money, but when you die, on your deathbed, you will receive total consciousness." So I got that goin' for me, which is nice. - Carl Spackler

  8. #8
    Sorry I'm a little confused, we should not set the indoor temp lower then 20 or we should not use it if the outdoor temp is below 20 ? What other controls should I be looking at or asking for ?

    Thanks

  9. #9
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    6,793
    You shouldn't set the thermostat lower than 13C (68F) because the indoor coil can freeze and can cause damage to the compressor. A low ambient kit can be installed to keep this from happening in low ambient conditions. Usually consists of something that slows the condenser fan to raise the pressure and a freeze protection thermostat to shut down the unit should it get to the freezing point. Or an EPR valve which is usually used in refrigeration applications.

  10. #10
    Quote Originally Posted by jtrammel View Post
    You shouldn't set the thermostat lower than 13C (68F) because the indoor coil can freeze and can cause damage to the compressor. A low ambient kit can be installed to keep this from happening in low ambient conditions. Usually consists of something that slows the condenser fan to raise the pressure and a freeze protection thermostat to shut down the unit should it get to the freezing point. Or an EPR valve which is usually used in refrigeration applications.
    I dont think we would ever set the indoor temp lover then 18'C. I guess I will have to look into some of these other controls so we can have the house at 20'C over night even if the outdoor temps dip down to 10-15'C.

    Thanks guys

  11. #11
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    6,793
    Most of us are in the US so posting in Fahrenheit is better communicated on this forum, for future reference.

  12. #12
    You got it. Can you even set the thermostat indoors to 13'C (55'F) ? I re read your post and was not sure if you meant indoor or outdoor temps ?

  13. #13
    Join Date
    Dec 2007
    Posts
    4,697
    Most Honeywell thermostat have a range for heating and cooling that can be adjusted.

    The OP is referring to outdoor temp.
    The Food Stamp Program, administered by the U.S. Department of Agriculture, is proud to be distributing the greatest amount of free meals and stamps EVER.
    Meanwhile, the National Park Service, administered by the U.S. Department of the Interior, asks us to "Please Do Not Feed the Animals". Their stated reason for this policy "... the animals become dependent on handouts and will not learn to take care of themselves."
    from an excerpt by Paul Jacob in Sun City, AZ

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