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  1. #1
    Join Date
    Nov 2011
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    Central Va.
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    How low for cut-out?

    Just curious as to what those here tell their customers about heat-pump function in low temperatures. I usually tell them to let the heat pump do what it can and let the control determine when auxillary is needed.

    Good advice, or not?

  2. #2
    Join Date
    Mar 2005
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    Suppy NC
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    4,509
    good advise IMO

  3. #3
    Join Date
    Nov 2011
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    Central Va.
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    Quote Originally Posted by tinknocker service tech View Post
    good advise IMO
    I'm in Virginia where we can see some low temps, but not as severe (normally and regularly) as further north. We did see three feet of snow not long ago, and that was, in the thirty years I have lived here, far beyond normal (loved it though, with the exception of shoveling the driveway).

    The main reason I ask is that many have the "heat pumps are drafty and cold" mentality (definitely not the case) and do not trust heat pumps to heat their homes. In eight years or more now, I have yet to have a customer tell me that the system will not heat their home.

    Thanks for the response.

    S.T.

  4. #4
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,375
    I'd rather have the outdoor temp change it over. Since we get below zero, I don't want a system constantly switching back & forth between HP & gas which is what they would do if we had no forced changeover. Or what the old Trane kit would call "unrestricted." Changing over at 30 gives the pump a chance to do what it can, below that, get the warm air of the furnace going. In Virginny you may be able to get by without an outdoor stat if your control doesn't require it to do dual fuel.

    Another post that might be better in tech to tech.

  5. #5
    Join Date
    Nov 2006
    Location
    Southeastern Pa
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    16,995
    Quote Originally Posted by S.T.Ranger View Post
    Just curious as to what those here tell their customers about heat-pump function in low temperatures. I usually tell them to let the heat pump do what it can and let the control determine when auxillary is needed.

    Good advice, or not?
    Posts like this belong in Tech to Tech, not AOP.

    AOP is for homeowners to ask about THEIR equipment.
    [Avatar photo from a Florida training accident. Everyone walked away.]
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    RSES CMS, HVAC Electrical Specialist

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  6. #6
    Join Date
    Jan 2004
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    Lancaster PA
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    66,750
    Ranger. I moved your threads to Tech to Tech.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  7. #7
    Join Date
    Nov 2011
    Location
    Central Va.
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    257
    Quote Originally Posted by beenthere View Post
    Ranger. I moved your threads to Tech to Tech.
    Hello beenthere, I thought I was restricted to AOP, being new.

    S.T.

  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    66,750
    No. AOP is for home owners and equipment owners to ask about their systems. tech to Tech is for techs to ask about equipment and service. And to get their post count up to 15 so they can apply for pro membership.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  9. #9
    Join Date
    Nov 2011
    Location
    Central Va.
    Posts
    257
    Quote Originally Posted by beenthere View Post
    No. AOP is for home owners and equipment owners to ask about their systems. tech to Tech is for techs to ask about equipment and service. And to get their post count up to 15 so they can apply for pro membership.
    My mistake. I saw where it said "new guests" post in AOP, which is why I moved "New Brand" there.

    Almost at fifteen, though, so I hope to apply fairly soon.

    S.T.

  10. #10
    Join Date
    Apr 2001
    Location
    Over Here
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    1,105
    Quote Originally Posted by S.T.Ranger View Post
    Just curious as to what those here tell their customers about heat-pump function in low temperatures. I usually tell them to let the heat pump do what it can and let the control determine when auxillary is needed.

    Good advice, or not?
    If that control is W2 or Aux on the thermostat, that advice may be a disservice to them if you leave it at just that. A lot of folks are using setback features on programmable t-stats nowadays. That creates a lot of needless strip heat operation daily.

    If the control is an OD sensor that locks out strip operation above 35 deg, that is a good thing. Our local PoCo pays us an incentive for installing one on each of their customers that have heat pumps with resistance back-up. It is wired so OD temp supercedes W2 call, but allows them to come on with defrost.

  11. #11
    Join Date
    Nov 2011
    Location
    Central Va.
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    257
    Quote Originally Posted by thermojohn View Post
    If that control is W2 or Aux on the thermostat, that advice may be a disservice to them if you leave it at just that. A lot of folks are using setback features on programmable t-stats nowadays. That creates a lot of needless strip heat operation daily.

    If the control is an OD sensor that locks out strip operation above 35 deg, that is a good thing. Our local PoCo pays us an incentive for installing one on each of their customers that have heat pumps with resistance back-up. It is wired so OD temp supercedes W2 call, but allows them to come on with defrost.
    I kind of let my thoughts overlap on this one: for dual fuel we use for the most part a TCONT402 which we set with the lockout, but for systems that are not dual fuel, this is where we recommend that the heat pump be allowed to perform to its potential.

    This is an area where you guys could probably really help me, as I am not a fan of dual fuel, as it adds to the cost of the equipment, as well as adds another bill for heat (gas). There are times when it is requested, but for our climate, I have not had one customer that has switched to heat pump that has not been satisfied both with performance, or with cost.

    Our local PoCo recommends programmable T-Stats so they can "save money" by cutting the temp. back: this is not good advise, particularly in extreme weather. What usually happens is that the system runs forever to recapture setpoint, and in winter, this means heat strips energize...so there goes the "savings."

    But again, this is an area that I hope to talk about with you guys, being the heating season. The last DF we did, we set the cut-out at fifteen with the HP op to come back at 20. The customer was paying high gas (LP) bills, and has told me since that in the last two years he has saved about four K in op costs. (we put in 14 SEER)

    Thanks for the response, hope to discuss this in greater detail at some point.

    S.T.

  12. #12
    Join Date
    Apr 2001
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    Over Here
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    Quote Originally Posted by S.T.Ranger View Post
    Our local PoCo recommends programmable T-Stats so they can "save money" by cutting the temp. back: this is not good advise, particularly in extreme weather. What usually happens is that the system runs forever to recapture setpoint, and in winter, this means heat strips energize...so there goes the "savings."
    Not with OD tstat. But the system does run a long time if it is a heat pump to overcome setback.

    My original post had nothing to do with dual fuel. I believe the dual fuel application requirement is regional. In our area, there is no ROI for dual fuel. Our NG prices are low when compared to electric rates for equivalent BTU. Factor in heating comfort when comparing NG heat to heat pump heat without strips, and it is a no-brainer for us. NG is the way to go for us.

  13. #13
    Join Date
    Nov 2011
    Location
    Central Va.
    Posts
    257
    Quote Originally Posted by thermojohn View Post
    Not with OD tstat. But the system does run a long time if it is a heat pump to overcome setback.

    My original post had nothing to do with dual fuel. I believe the dual fuel application requirement is regional. In our area, there is no ROI for dual fuel. Our NG prices are low when compared to electric rates for equivalent BTU. Factor in heating comfort when comparing NG heat to heat pump heat without strips, and it is a no-brainer for us. NG is the way to go for us.
    I am really surprised at that. I would think heat pump would be a natural choice in Fl. I wonder how power costs compare with us.

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