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Energy Cost Comparison - Am I doing this right?

Singh -
According to tekmar, use of outdoor reset reduces standby losses. I don't know if there's a formula. You may want to read tekmar's Essay 004, which you can get at their site www.tekmarcontrols.com.
FYI, in my present house, I went 13 seasons at 180°F., and am about to start my 7th season with injection mixing. I can't tell you what contribution to savings the reset has made, because at the same time, I replaced the boiler with a more properly sized one (0.75 gph vs. 1.75 gph); began using outside combustion air; added 2 zones for more precise temperature control; installed an indirect water heater (old boiler had a dhw coil); and added another R-25 to the attic insulation. This was all in 1999. Annual fueloil consumption went from 1250 gallons to 900; this is for heat and hot water. I also added hydronic heat to a sunroom which was previously heated with electric baseboard. So, while saving about 28% on fuel, I'm heating an additional room, and my basement is cooler in summer, reducing my air conditioning load. I'm about 50 miles south of Albany, NY. Hope this helps a little.


  • John Starcher_4
    John Starcher_4 Member Posts: 794
    I have a client........

    ...who needs a new furnace. Existing fuel oil unit has worn out its welcome. Client is asking for recommendations as to what to replace it with, relative to fuel costs (crystal ball, anyone?).

    Anyway, here's what I am coming up with based on our local rates:

    Electricity = 0.11/KWH = $3.22 per 100,000 btu

    LP Gas = 1.64/gal (today) = $1.94 per 100,000 btu

    Fuel Oil = 2.39/gal (again, today) = 2.02 per 100,000 btu

    Now, to complicate things, how would a heat pump factor in? The heat loss is calculated to 80,700 btu @ design, cooling load is 2 1/2 ton at design.

    Can anyone help me out?

  • John Starcher_4
    John Starcher_4 Member Posts: 794
    Just to clarify....

    ...the above numbers are based on efficiencies of 100% for resistive electric, 92% for LP, and 85% for fuel oil

  • RadPro
    RadPro Member Posts: 90

    nice to updated cost per btu comparisons ... thanks Paul
  • thfurnitureguy_4
    thfurnitureguy_4 Member Posts: 398

    Sorry just more questions. If radiant electric heat is 100% efficient than how could a heat pump be better? Is it more than 100%? What ever pickup you get from the environment would have to be the diference between baseboard and a heat pump.
  • Steve Ebels_3
    Steve Ebels_3 Member Posts: 1,291
    I just ran a comparison

    Heat pump (Climate Master Tranquility, ground source open loop vs 92% LP furnace) Operational costs with the HP were $1440 annually as opposed to $3,100 for the Furnace and sepsrate LP water heater. That was with LP at $1.40/gl. Who the heck knows where it's going now. Electric here is about $.085 per KWH.

  • Heat pumps generate 2 or 3 times as much heat per KWH as using straight electricity does.
  • Steve Ebels_3
    Steve Ebels_3 Member Posts: 1,291
    A heat pump

    Adds the energy (heat) stored/dumped into the ground to the KW input to run the compressor. The Tranquility that I priced for these folks has a ratio of about 3:1 energy produced vs energy consumed. In areas where you have the grround space to use a heat pump, furnaces are obsolete. The most efficient system you could get would be a good GSHP coupled to a low temp radiant system.
  • John Starcher_4
    John Starcher_4 Member Posts: 794

    thank you. I should have clarified, though, that this would be a straight air-to-air heat pump, not a geo.

    HSPF of the unit I'm looking at is a minimum 7.3, but we'll look at higher efficiency units, also.

  • singh
    singh Member Posts: 866

    I am also running some annual energy cost numbers.
    But I am unsure about the way to offset the result if
    outdoor reset is used.
    Can some one give me a formula for this?

    Thanks in advance.
  • singh
    singh Member Posts: 866

    george where are you? I'm in columbia county.
This discussion has been closed.