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  1. #1
    Join Date
    Oct 2006
    Location
    Midwest
    Posts
    282

    Confused Utility company control of residential heat pump?

    I'm trying to decide between a standard A/C unit or a heat pump when I replace my home furnace & A/C unit this Spring. An HVAC contractor mentioned that the electric rates for heat pumps were lower than for an A/C unit. I got the HP rate schedule from my utility co. which states that the HP has to have it's own meter installed. The rate schedule states that "The duration and frequency of interruptions will be determined by the company. The direct load control device will be cycled on a schedule of 15 minutes on and 15 minutes off normally for six hours with a maximum of eight hours per day. Interruptions will normally occur on high demand weekdays during summer months."

    Wouldn't this damage the heat pump or shorten its life span if the power is cycled off & on like this while it's trying to run? There's no mention of whether the furnace is also wired to the HP meter so it cycles off & on, too. In either case, am I looking at possible damage to it also? Sounds pretty flakey to me.

    BTW, the HP "reduced rate" is a joke - $6/month lower customer charge, but only $0.001 lower charge per KWH used, so it appears that an HP running off the existing meter would be the way to go.

    House is approx 2400 s.f. in South Dakota, built in 1994, tight & good insulation.

    Comments & advice would be appreciated. Thank you.

  2. #2
    Join Date
    Nov 2006
    Posts
    193
    works ok if you want to save, I've seen it both ways 24 vac and 240 vac, both had a time delay not to damage the compressor, so it could equalize, they do water heaters too...

  3. #3
    Join Date
    Oct 2006
    Location
    Midwest
    Posts
    282
    Quote Originally Posted by bltinnc View Post
    works ok if you want to save, I've seen it both ways 24 vac and 240 vac, both had a time delay not to damage the compressor, so it could equalize, they do water heaters too...
    Thanks, but it seems to me it would be just like a power outage and the heat pump could lose power without any time delay. However, I'm not an HVAC tech. How could a time delay protect the compressor if there is no utility co. connection to the control board? And wouldn't the cycling generate error codes in the control system/t'stat/furnace?

  4. #4
    Join Date
    Nov 2006
    Posts
    193
    they have a relay that breaks to circuit from the thermostat that cuts the condensor just you would if you cut the heat or ac, or it was satisfied....course they might cut it off on the hottest day r coldest when a brown out is occuring

  5. #5
    Join Date
    Mar 2006
    Location
    OK
    Posts
    2,144
    Quote Originally Posted by roymcoy View Post
    Thanks, but it seems to me it would be just like a power outage and the heat pump could lose power without any time delay. However, I'm not an HVAC tech. How could a time delay protect the compressor if there is no utility co. connection to the control board? And wouldn't the cycling generate error codes in the control system/t'stat/furnace?
    Cutting the power in itself isn't what damages equipment, it's the compressor cycling back on after a power blip before pressures have had time to equalize that's hard. The time delay keeps the unit from coming back on for XX minutes after shutting off. Many thermostats do the same thing.

    I haven't run into damage from one of these devices but I have seen no cooling calls from people not realizing they had one. Unless they offer a lot of $$$, it doesn't seem worth it to me.
    Never knock on Death's door. Ring the bell and run, he hates that.

    Views expressed here are my own and not neccessarily those of any company I am affiliated with.

  6. #6
    Join Date
    Oct 2006
    Location
    Midwest
    Posts
    282

    Lightbulb

    I understand now. Thank you.

  7. #7
    Join Date
    Feb 2007
    Location
    Kansas City, Mo.
    Posts
    264
    The utility company in my city is offering free new digital thermostats with free installation. This, of coarse, is a rouse so they may control the electricity to your home's unit to prevent brown outs. They'll cycle them off and on but give no one breaks on their bills, even for the extra amps drawn for each motor start-up (which we don't have any control over).

    I'll keep my old thermostat, thank you very much (in a sarcastic tone).
    CHECK PLEASE!

  8. #8
    Join Date
    Jun 2004
    Location
    4H: Hot, Humid Houston H.O.
    Posts
    3,304
    Quote Originally Posted by HOT SHOT View Post
    The utility company in my city is offering free new digital thermostats with free installation. This, of coarse, is a rouse so they may control the electricity to your home's unit...
    Utilities under regulation do all sorts of weird things that serve some kind of public purpose. Those cutoff programs to limit an AC to 50% duty cycle are just one example -- I do agree the customer deserves much better than $6/mo to compensate him. Think about it, the only AC which will be able to maintain setpoint will be one drastically oversized! It goes without saying this cutoff will be only during times of peak demand, when both you and the utility need the power.

    It will help at least one member (me) if you will tell the name of your utility. The rate plans are in the form of public records we can look up, and sometimes it will result in being able to help provide answers. Other times it will just help satisfy my curiosity.

    Is Westar the utility for Kansas City? Is Black Hills Corp the one for S. Dakota? Just sincere curiosity. Where I live in Texas they do less and less of that monkey business but rates are rather higher so I might envy you overall.

    Best wishes -- Pstu


    .

  9. #9
    Join Date
    Oct 2006
    Location
    Midwest
    Posts
    282
    My electric utility co. is Xcel Energy/Northern States Power Co. based out of Minneapolis. The rate schedules I compared are my existing - residential underground vs. residential heat pump service. There is a $0.023 / KWH savings (Winter) , $0.001 /KWH savings (Summer)and a $6.05 customer charge savings/month with the heat pump rate. The customer has to pay for the installation of the additional (2nd) meter socket for the heat pump meter (one time cost). Difficult to estimate overall savings compared to existing Nat Gas furnace & A/C split system. In spite of the better Winter rate/KWH, if I go with the HP, I'll probably not go for the 2nd meter & HP rate schedule so I can avoid handing operational control over to the utility co.

    Appreciate your help, guys!

  10. #10
    Join Date
    Oct 2006
    Location
    Midwest
    Posts
    282
    Quote Originally Posted by HOT SHOT View Post
    The utility company in my city is offering free new digital thermostats with free installation. This, of coarse, is a rouse so they may control the electricity to your home's unit to prevent brown outs. They'll cycle them off and on but give no one breaks on their bills, even for the extra amps drawn for each motor start-up (which we don't have any control over).

    I'll keep my old thermostat, thank you very much (in a sarcastic tone).
    Apparently that is the deal, at least in some locations, with Carrier's new "Edge" t'stat. Connected to & controlled by the utility co. (Not available in all locations, your mileage may vary - batteries not included - some assembly required - etc..........) Sounds like Big Brother to me - George Orwell was just 23 years off in his time estimate as far as HVAC goes!

  11. #11
    Join Date
    Jan 2007
    Location
    Mn the state where absolutey nothing is allowed
    Posts
    1,381
    if you go with the "utility curtailment" as carrier calls it..do not expect good cooling results if you have a setback thermostat.if excel is cycling their box when your t-stat comes out of a program your ac/hp will never catch up running only 50% of the time

  12. #12
    Join Date
    Oct 2006
    Location
    Midwest
    Posts
    282
    Carrier's "Edge" t'stat isn't available in my area as far as I know, but I wouldn't be interested anyway for the reasons posted above. It was the utility co. cycling of power to a heat pump that concerned me. Definately sounds like something to avoid.
    Thanks again.

  13. #13
    Join Date
    Jun 2003
    Location
    Chicago, IL
    Posts
    4,565
    if your system is properly sized, it will run almost continuously on the hottest day of the year. The hottest days are most likely the days which the utility will cycle the controller. If your system needs to run 100% of the time, but the utility only lets it run 50% of the time, i can guarantee you will not be comfortable.

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