LP sucking boilers

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    • #278131
      Willie J Davis

      Two of us have hydronic in-floor systems which we cannot use due to the appetite of our LP boilers. Mine is using 500 gallons per month while the house is unoccupied and some zones OFF. Have a boiler-mate hot water system attached. Any ideas why we’re using so much LP? House is 4000 SF, slab on grade. two-story. Installer says this is normal usage. Who could afford this?

    • #297783
      Harold Kestenholz

      A gallon of LP gives about 93000 btu. At 80% efficiency, it gives off 75000 btu into the house. A well-insulated new house built today has a heat loss of about 25 btuh per square foot. Your house is 4000 square feet. Your heat loss per hour is 25 btuh times 4000 square feet – or 100,000 btu per hour during the average coldest day.

      It is now a cold average month. So you will use 1.33 gallons of LP per hour times 24 times 30 days in the average coldest month If you keep your house at 68F degrees. Your maximum use will be 1357 gallons of LP in a month times the LP rate, which may be $1.70 per gallon, so $2306 in the coldest month is possible. Electricity would cost more, oil would cost about half that.

      A person who could afford that would be someone who could afford to live in and buy a 4000 square foot house with one of the most expensive (because radiant is the most efficient) heating systems.

      Most everyone else lives within a 1400 square foot home and pays about $300 per month on the budget plan. If you keep the house set back to 55F, you could expect to average about $1000 per month on the budget plan (evening out the cost over 8 months.) So you are doing very well. You could change over to oil and pay for a new boiler every year from the savings.

      If you would like to compare fuel costs there is a fuel comparison program at the Hydronic Network:

    • #297784

      For what it is worth;
      I too have an in-floor radiant heating system running off LP, and have found it to be very expensive. I had to change my propane tank from 500 gal to 1000 gal just to make it through the 30 day refuel schedule. No need to tell you how much fun it is to receive the fuel bill now. Only thing worse, is running out of fuel during the highest usage months in Jan and Feb, and being broke and cold.

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