all elecric or propane back up?

Discussion in 'Quotes and Proposals' started by HHarpel, Mar 29, 2013.

  1. HHarpel

    HHarpel New Member


    My husband and I are building a house in Bellefontaine, Ohio, and we have had some conflicting information given to us. Some tell us to do all electric geo unit, such as climatemaster or waterfurnace, and some tell us to do a carrier geo system with a propane backup furnace. The winters get very cold here, but we are doing sprayfoam insulation. I've heard of people with very high electric bills during colder months with the all electric unit using backup heat strips when the geo can not keep up, but today I had an installer tell me that doing a propane backup is not the way to go? Any information would be helpful. Electric or propane backup?
  2. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Much depends on your local energy costs. Compare the delivered energy by each fuel. A gallon of propane (92,250 btu) burned in a non-condensing furnace (AFUE ~80%) delivers ~74,000 Btu, about the same amount of heat as 22 kwh electricity. Stated another way, if electricity in your area costs a dime per kwh, propane would have to cost less than $2.20 / gallon to be a cheaper source of heat. I'm willing to bet propane back up would be significantly more expensive to buy and install, as well.

    Also know that total cost of aux heat usage shouldn't be more than $100-200 for a well-designed system in a typical home. I can't know what you mean by "very high electric bills during colder months", but I doubt propane would be of much help.

    Propane is an excellent fuel for grilling meat, operating standby generators, and starting wood fires, but cost per delivered Btu should be carefully compared to alternatives before using it for bulk heating tasks such as space heat, water heating, or clothes drying.
  3. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Generally a split system geo on a propane furnace has a similar installation cost to a packaged geo in my AO.
    Generally split systems with propane back-up have slightly higher operating costs than package geos (heat pump, blower and aux all in one package). This is not only due to Curt's explanation, but also due to the fact that the (in a split system) geo fan coil is downstream of the furnace, so they can not run simultaneously. Meanwhile auxiliary on a pkg unit is downstream and they can run in tandem therefore the geo is still contributing heat while aux is on.

    So why would people pick a split system?
    1) Auxiliary coils can require as much as 100 amps to themselves which requires quite a bit of extra electric infrastructure.
    2) Some folks have natural gas available (this is often cheaper than electric aux. even though they can't run in tandem).
    3) Smaller generator is required to run a furnace in areas with frequent and prolonged power failures.

    Reason #3 is the most common in my A/O.

    Something about the way you phrased " and some tell us to do a carrier geo system with a propane backup furnace." makes me think "some" means "one". My spidey sense is tingling. Does that company have a lot of installs with geo?
  4. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    The supplement heat electric element is designed to save you money, both upfront and in operational costs.
    You only reach spikes of very cold days a few days or nights per year. I does not make sense to design and install a capacity which you only use a few days/year. Plus the smaller system now runs more efficient the rest of the year. So paying $50-150 actually saves you $100 in overall operational costs/year. Plus you pay less upfront, since the system now can be smaller. Only when the system is not sized correctly, the supplement heat portion is too much.

    The propane backup does not make much sense at all. Operational costs for propane almost equals those for electric heat, now you are paying significantly more upfront, and you need to maintain now a propane furnace, electric heat elements do not require any maintenance.

    If a company tries to sell you a geo system plus a propane backup, don't walk away from them,....RUN!

    It clearly indicates a lack of experience on the side of the company.
  5. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Not suprisingly I disagree to both of these comments.

    I did mention my antennae were twitching about the installer who suggested split.

    I also mentioned that reasons exhist where one may select propane or other auxiliary. We have some aging and unreliable grids in my area and people experience lengthy black-outs. A propane furnace particularly with ECM blower uses very little generator capacity where package geo in many cases would cause my customers to buy 3 times the generator.

    Without many of the particulars it is easy for us to have a little bit of a cookie cutter mentality, but if the company that works in your area suggests something it may be due to local anomalies that we are not privy to.
    This is why we suggest you vette the contractor first and pay attention to design later. If you have a good and experienced contractor, the rest will take care of itself.
  6. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    I don't disagree with Joe a lot, but this time I do. Get a softstart/Intellistart and disengage the aux heat, and your generator need can be rather minimal. Especially for a 3-4 ton unit. Thus I don't see a scenario where a propane furnace for backup reasons would be make much economical sense, mainly because of maintenance and upfront costs. The reasoning for propane here in this post was "cold winters". If your geo system does not serve you well during a cold winter, it is not designed/sized well.
  7. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Agree to disagree on whether propane ever makes sense for auxiliary.
    Still disagree on the mere suggestion indicating a lack of experience of installer and advice to "run away".......(cmon doc you might scare a customer off me :cool:)
  8. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Having initially failed to consider the cost impact of loading 60-120 amps of additional electric circuits on homes that might only have just 100 amps, I temper some of my condemnation of propane backup.

    A weak, failure-prone grid in a cold climate would tip the scale further in favor of propane backup, even if pricey. Nat Gas, (NG) would be virtually a no-brainer in those circumstances, though NG is rarely piped to rural addresses.
  9. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Some of the wealthiest neighborhoods in the Detroit metro area are rife with power failure due to aged grids and overhead powerlines susceptible to storm damage. Outages often last days. Natural gas is available to these same homes who all have 20 or 30 K standby generators. They also have multiple heat plants which means 30K might not be enough generator to start their geo systems.
    Don't tell these folks they need more generator- put in an NG split.
  10. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    OK, let me rephrase.
    I personally yet have to see the the project where going with propane backup makes economical sense, both upfront and for operational costs.
    Suggesting this without a very good reasoning still suggest a lack of experience of the installer.
    Intellistart soft start kits from WF work on other HPs as well. They significantly reduce the start up amperage.
    Homes large enough to use multiple heat plants are obviously special considerations. But they mostly have fireplaces which are no cost supplement/emergency heat plants.
  11. wisailor

    wisailor New Member

    Here is a thought.

    I talked to several installers and received several different replies in regards to propane back up, one said DEFINITELY NOT!!!, the other felt it was a good idea.

    My deciding factor was a dual fuel electric rate. If I had a propane furnace my winter cost for electricity would be $.066 per KWH and summer rate is $.126 per KWH. If I went with an electric backup my year round rate for electricity would be $.128 per KWH.

    I went with the dual fuel rate and a propane backup.
  12. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Is that for supply (the power plant) and the delivery (the grid) combined?

    Plus how much more did the dual heat setup cost?
  13. wisailor

    wisailor New Member

    I put in a 96% 120000 BTU Goodman furnace with ecm motor $1100.00 before utility rebate. 5 ton water A coil, Bosch 5 ton unit water to water unit, and a B&D 2 pump flow center $7500.00 before utility rebates, There was a field in the house that was installed in 1984, that I had to clean up the connections and rebuild the manifold. Since it is a water to water unit I am also putting hydronic towel bars in the bathrooms and a heated floor in the master bath.

    The electric rates I listed where the final billing amount.
  14. moey

    moey Member

    The more propane you buy the cheaper it gets. You will not be using much so you'll pay a lot more for it then your neighbor who uses 1400 gallons a year. You wont get that cheap price someone tells you they got without jumping through hoops. Something to think about. If your concerned about power failures consider a wood stove or something that doesn't require electricity. Unless your rolling in money then get a standby generator and a propane backup and may as well add in a electric coil so you can use what is cheaper.

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