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  1. #14
    Join Date
    Sep 2012
    Posts
    7
    Thank you all for your useful inputs. Now I have several good options to look at. I like the dual fuel (heat pump + propane) since it gets below freezing only for a short time in winter. Also, if later we have solar panels and power to spare, I can adjust the switching threshold lower and get our good old sun to good use.
    Now I can ask informed questions to my contractors.

    Benoit

  2. #15
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,145
    If the time below freezing is minimal the propane furnace may not have a reasonable payback time vs. electric heat strips.

  3. #16
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Quote Originally Posted by BaldLoonie View Post
    I don't buy that 15% is insignificant. BUT since you aren't in a real cold climate. I was thinking along the dual fuel line myself then I saw it brought up already. The cost to go split system 95% over staying packaged probably will negate any savings, something to keep in mind.

    Why no 95% pack? From what I've been told these are the 2 most common reasons: packs are usually used in the south so little need for the super efficiency. Also, packs are used light commercially and utility bills are paid by tenants so there would be little call for anything but the cheapest units.
    I think there also the whole issue of managing condensate in an outdoor unit.

  4. #17
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    6,371
    Quote Originally Posted by motoguy128 View Post
    I think there also the whole issue of managing condensate in an outdoor unit.
    Managing the condensate would be easy but like BL said residential packs are only used in the southeast mainly and we have a mild winter

  5. #18
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,699
    Quote Originally Posted by BaldLoonie View Post
    I don't buy that 15% is insignificant. BUT since you aren't in a real cold climate. I was thinking along the dual fuel line myself then I saw it brought up already.
    +3. Dual fuel absolutely.


    On the 80 to 95% issue. The savings isn't as simple as multiplying combustion efficiency gain by energy bill. Savings could be as much as 50%, lot of "it depends".

    On the flip side, I've seen 95% replace 65% and NO savings. Good design is one of the big "it depends" that often gets overlooked by people assuming this is a plug n play equation.

    How big is the annual bill? That's the place to start. 15-50% of $300 might not be very interesting, $3000 might be...
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  6. #19
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,699
    Quote Originally Posted by BaldLoonie View Post
    Propane? You are definitely a candidate for dual fuel. In our climate, the gas backup will hardly come on meaning cheap heat from the heat pump. We've been doing it for several years with nary a complaint. Get a control that handles the dual fuel and have it switch to gas at 30. you will be comfy.
    Oh.

    If you go with combustion instead of straight HP, that makes the split MUCH more appealing. Be a good idea to consider units that defrost on pressure rather than timer.

    Again, current annual consumption is really important place to start.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  7. #20
    Join Date
    Sep 2012
    Posts
    7
    Quote Originally Posted by tedkidd View Post
    Oh.

    If you go with combustion instead of straight HP, that makes the split MUCH more appealing. Be a good idea to consider units that defrost on pressure rather than timer.

    Again, current annual consumption is really important place to start.
    We are in the upper part of your range ($2760/year). Currently our cost is at $1.99/gal, so that means we consume around 1387 gal/year.
    What does "straight HP" mean, and what is the difference with combustion?
    I thought all propane furnaces used burners to heat the forced air...

  8. #21
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,699
    Oooo. Big bill.

    Straight heat pump means no propane furnace, just heat pump. Dual fuel is like a hybrid car. Has gas and electric, and attempts to optimize the source based upon conditions. Typically, gas runs below say, 20f, and heat pump runs above that.

    My inclination would be:

    If you stay with an outdoor unit, go with the highest efficiency heat pump you can find. Straight heat pump. Grid heat will come on to assist if the pump can't carry the structure alone on the coldest days.

    If you go with an indoor unit, energy assessment time. I'd want a lot more details about the house and your intentions, and property values/quality of your neighborhood. All these things have a stake in understanding your best interests and developing a really well tailored recommendation.

    An energy assessment before big, long term capital investments is a good idea. Pretty painful to learn about missed opportunities 1-2 years after spending a bunch of dough on improvements.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  9. #22
    Join Date
    Apr 2010
    Location
    NC Sandhills
    Posts
    391
    Do you have at least 200 amp service. Some older homes do not have enough power to handle a "straight heat pump" which uses electric resistant heat strips. With a dual fuel this wouldnt be a problem, like has been said. If your power supply can handle it a normal heat hump with aux heat strips may be cheaper than lp.

  10. #23
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,145
    Some heat pumps only need a double 30A braker, most only need a double 60A. A large home in a cold area could need 2 double 60's. Once you go over 1 double 60A then you would need 200A service.

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