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  1. #1

    Question

    What is the value of an outside thermostat? I am having an Amana RTG Ultron 16 SEER Heat Pump with Variable speed indoor air handler and two-stage compressor put in next week. One of the options is an outside t'stat. I live in southern Georgia and have a 3200 square foot home.

    Saw somewhere that somebody suggested adding outside t'stat but can't remember why or what part of the country they were from.

    What are the benefits, initial costs, etc.

    Thanks in advance for all replies.

    J. D.

  2. #2
    Join Date
    Apr 2005
    Location
    NE PA
    Posts
    698
    Outdoor thermostat options can be for a couple of purposes. Most common is to have an outdoor stat to lockout the auxiliary heat when the outside temperature is above a set value. This prevents the costly auxiliary heat from coming on if you turn up the thermostat setting more a a couple of degrees, and it is warm enough for the heat pump to reasonably handle. The lockout is usually set at 30 or so degrees.

    The other use of an outside stat is to lock out the heat pump at extreme cold temperatures, where available heat extraction is minimal, and operation may do more harm than good. This is usually set to the low teens or single digits as a cutoff.

    paul

  3. #3
    Join Date
    Mar 2004
    Posts
    1,042
    Having an outdoor thermostat would be useful in your area for the first reason tecman cited... unless you intend to set the thermostat to one temperature and not really adjust it thereafter.

    It doesn't get cold enough in your neck of the woods to worry about shutting off the heat pump (tecman's second paragraph) in very cold conditions. This is really only necessary in areas where it routinely drops below zero degrees.

    Depending on what (indoor) thermostat you get, this function may be included without the use of an outdoor thermostat. Many nice thermostats with an outdoor temperature sensor can be configured to restrict the use of the auxilary heat when it's above X degrees outside. Since you're getting a two-speed condensing unit, you won't have much choice but to get a nice thermostat, so there's a fair chance this will already be included.

    Have you selected your (indoor) thermostat yet?

  4. #4
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,038
    The Vision Pro with outdoor thermistor will allow high limit to shut off backup and low limit to shut off pump. Personally if you have a time/temp defrost, I'd shut off the pump around 0. My personal feelings from experience around here. And certainly lock out backup as cool as you can, especially if you have people playing with the stat all the time. Or lock the screen

  5. #5

    out door thermostat

    I live in Memphis Tn. and we put out door thermostat to shut heat pump condensor down any thing below 40 so the gas heater will come on hope you putting this on gas furnance. that way lot people doing now since gas is so high that is what i will do when my unit goes out

  6. #6
    Join Date
    Mar 2004
    Posts
    1,042
    This is not a dual fuel application, thurman- electric backup.

    As for zero degrees, this install is in south Georgia. That one's a non-issue

    The VisionPro would be a great thermostat choice, no doubt, and of course with the outdoor thermistor. Dunno what the OP's contractor has proposed, though.

  7. #7
    Join Date
    May 2002
    Location
    Houston Texas
    Posts
    6,320
    If you are purchasing the Ultron and the 1213431 humidity control t'stat I recommended in your other thread the outdoor thermistor is used to reduce winter window condensation. This only a heat pump option so I am not familiar with what it does to do this and can't speak to the other reasons stated.

    As to cost it is not that expensive an option in conjunction with the 1213431-humidity control t'stat.

  8. #8
    Join Date
    May 2002
    Location
    Houston Texas
    Posts
    6,320
    The problem with the Vision Pro is for humidity control it only over cools it does not control CFM. When installing the RTG it is important to get a t'stat that is designed to work with the software of the ECM.

    If you buy a Lennox get the Signature stat if you buy Carrier get the Infinity or Thermidistat. When buying advanced technology go with the horse that brung you.

  9. #9

    Thanks ALL

    Classical & others:

    Thanks for your input about the thermostat choices. I feel like I now know what to tell my installer I want -- so far, I am very happy with how he listens, explains things, checks out entire house, and returns my calls. He will begin install in a few days. I have called several people that he has done work for and all are very pleased.

    If anyone is in the South Georgia (Valdosta) area I would be happy to share with you his name. I contacted nearly everyone in Valdosta and am by far most pleased with him. However, he has not installed anything yet -- I trust him as much as I could any installer so I hope all goes well.

    J. D.

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