Page 1 of 2 12 LastLast
Results 1 to 13 of 18
  1. #1
    Join Date
    Jun 2009
    Posts
    33

    Air Heat Pump Systems with Natural Gas Heating

    What are the best air heat pump systems that use the heat pump for cooling but use a natural gas heater for heating?

    Are there any reasons to not consider that design instead of an all-electric heat pump for cooling and heating? Obviously we are hoping to save on heating costs by using cheaper natural gas, but I understand it may not be so straightforward, and in certain temperature ranges using the air heat pump for heating may be more efficient than natural gas. I guess the perfect unit would sense those conditions and switch between electric and natural gas heating based on outside conditions?

    I also understand that an air heat pump does not work well with the temperature outside below 40F, so the unit would of necessity need to switch to natural gas in that case.

    I would have preferred the simplicity and low operating costs of geothermal, but I have sadly concluded that this is a technology only for the extremely rich.

  2. #2
    Join Date
    Jun 2009
    Location
    Kamloops B.C.
    Posts
    31
    There are a number of systems that do use air source heat pumps and switch automaticly to nat gas Carrier Infinity and Bryant Evolution systems

  3. #3
    Join Date
    Jun 2009
    Posts
    33
    Quote Originally Posted by HVAC_James View Post
    There are a number of systems that do use air source heat pumps and switch automaticly to nat gas Carrier Infinity and Bryant Evolution systems
    Do you have any experience with either of those, and how do they compare against a more standard approach of an electric condensor HVAC system combined with natural gas heater?

  4. #4
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,770
    Pretty much ALL manufacturers. Make units that can be used as dual fuel heat umps.
    And you can always get straight A?C with a gas furnace.
    Contractor locator map

    How-to-apply-for-Professional

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

  5. #5
    Join Date
    Dec 2002
    Location
    SouthEast NC ICW & Piedmont Foothills
    Posts
    7,635
    are you reffering to a kool-fire

    had a ribbon burner under the o/d coil
    It`s better to be silent and thought the fool; than speak and remove all doubt.

  6. #6
    Join Date
    Jun 2007
    Location
    The Twilight Zone
    Posts
    2,964
    Quote Originally Posted by westes View Post
    What are the best air heat pump systems that use the heat pump for cooling but use a natural gas heater for heating?

    Are there any reasons to not consider that design instead of an all-electric heat pump for cooling and heating? Obviously we are hoping to save on heating costs by using cheaper natural gas, but I understand it may not be so straightforward, and in certain temperature ranges using the air heat pump for heating may be more efficient than natural gas. I guess the perfect unit would sense those conditions and switch between electric and natural gas heating based on outside conditions?

    I also understand that an air heat pump does not work well with the temperature outside below 40F, so the unit would of necessity need to switch to natural gas in that case.

    I would have preferred the simplicity and low operating costs of geothermal, but I have sadly concluded that this is a technology only for the extremely rich.
    It sounds like you are talking about a "dual fuel" system - heat pump with gas furnace back-up. Very common.

    What is your delivered price for electricity (in cents per kw-hr)? Delivered price = generation + transmission + distribution.

    What is your delivered price for natural gas (in $ per therm or $ per ccf)?

    Heat pumps put out heat down to below 0. They'll run contantly and the output temps/btu's drop like a rock, but they still put out heat. The question is of cost effectiveness for you, and to know that, you need to know your utility rates.

  7. #7
    Why not a gas-absorption heat pump? It is an air-source heat pump using natural gas instead of electricity and providing heating and cooling alternatively.
    Visit ww.robur.com/us and you will find all thenecessary information

  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,770
    An absorber would be fine. Until he finds he can only get one company in his area to work on it. Or has to wait a long time for parts when its needs a part..
    Contractor locator map

    How-to-apply-for-Professional

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

  9. #9
    In which area is he located? Here in Europe absorption HP are pretty well known and I know that they are growing fast also in the US.

  10. #10
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,770
    Quote Originally Posted by fsprea1977 View Post
    In which area is he located? Here in Europe absorption HP are pretty well known and I know that they are growing fast also in the US.
    How fast are they growing in the USA. And where did you hear this.
    Contractor locator map

    How-to-apply-for-Professional

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

  11. #11
    Join Date
    Jul 2005
    Posts
    5,381
    Quote Originally Posted by westes View Post
    Do you have any experience with either of those, and how do they compare against a more standard approach of an electric condensor HVAC system combined with natural gas heater?
    Net savings will require an extensive amount of calculating. Note that even if the calculations yeild $XXX.xx savings in energy dollars per year, there are no guarantees that you'll actually save anything at all in reality, it could even end up costing more in the long run. It's impossible to predict utility rate changes, maintenance costs, and equipment longevity.

    In some areas dual fuel actually costs more to run, especially if the fossil fuel being used is propane. The dual fuel system also will generally cost more up front.

    The primary advantage of the dual fuel system is that the furnace will operate on a portable generator, whereas the heat pump portion of the system typically will not. So with dual fuel you can heat the home during a power outage if you have, or get, a portable generator.

    There are several online energy comparison calculators available. I don't have any links handy, but you can Google, or wait and somebody here might post a link or two.

    I can't guarantee the accuracy of any of those calculators. Some simply do not take into account all the parameters involved, and some make assumptions that won't necessarily apply to your installation or habits.

    The Infinity/Evolution systems are high end, top of the line. They provide exceptional comfort, but cost a bit more. Virtually any heat pump can be configured as dual fuel though. The options available to you, as far as equipment types, brands, and pricing can be overwhelming. If you decide on a system, the quality of the installation and set up are going to be more important than the brand. Warranties also vary considerably, so figure those into your equation.

  12. #12
    Join Date
    Apr 2009
    Posts
    523
    Geothermal doesnt have to be that expensive. Really depends on the type of wells required. I'm assuming in your case that is the expensive part.

    Dual fuel around here is esp. cost efficient. I even went that route in my own home. Its even better around if you do have propane because propane cost are very expensive here.

    Switching from gas and a/c to dual fuel is usually benefitial, switching from a heat pump to dual fuel is hit or miss. However there is usually increased comfort with a fossil fuel furnace vs heat pump air output temp.

    The infinity stuff is nice because its a packaged deal. Its all designed to not only work together but work very well together. But you can use any heat pump + furnace you'll just need a good installer/tech to set it up for you...

  13. #13
    Join Date
    Jan 2007
    Location
    TN
    Posts
    49
    I read all I could before I ordered my Nordyne (Frigidaire) ihybrid 15 SEER 4 stage heat and 2 stage cool VS motor etc duel fuel package unit. We replaced an old Heil gas pack running on propane it was killing me with gas bills....... Second week in service and we have a problem with low temperature compressor startup. It will be fixed tomorrow so they say. With all these bells and whistles I can just imagine continuing problems. Technology is great WHEN IT WORKS. Really high reviews of the product but from what I understand when they changed the old E type unit to a F type that meets the Obama tax credit criteria the Nordyne engineering group had decided that a crankcase heater would be unnecessary since its 70 watts of power usage would decrease the SEER rating too much for the unit to qualify for the tax credit. They were exactly right that under normal conditions the crankcase heater is unnecessary but when the temp drops to zero for several nights and the unit has only been run on aux since the compressor lockout is setup at 30.The temp never got back above 30f for 5 days but the the sun comes out and on day 5 and shines ever so bright and warm on the poorly placed outdoor temp sensor. Then by the magic of solar energy the 9421 tstat believes it is 31f outside when in fact it is 19f, the tstat kicks the unit into heat pump mode and low and behold the copeland scroll compressor is trying to start up and hammering like it is going to knock the entire side of the house in. SLUGGING. I am negotiating for a new unit but they are going to add a heater and do a restart and test, they say the compressor is probably not harmed. How much hammering can a compressor take without damage? I may have to bring my wood stove back in from storage Sigh I thought those days were over and technology had saved me.

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event