Different Systems Can Yield Efficient Heating
QUESTION: My old furnace needs to be replaced and I want to get a super-efficient model. How do I determine whether gas, oil, wood or a heat pump is best and what are the most efficient models of each available?
ANSWER: There have been many recent efficiency and comfort improvements in each type of central heating system. Selecting the proper model and fuel type for your area can lower your heating costs by up to 50%.
The most efficient model is not always the best economic choice for every home. For example, if your home is energy efficient with low energy usage, the additional savings from installing a super-efficient model over a regular high-efficiency one may not pay back the higher initial cost.
Natural gas is typically the preferred fuel over oil and propane. Some of the new gas furnaces have efficiencies as high as 95% and have special blowers and controls for extra comfort.
A propane furnace is similar to a gas furnace in efficiency, comfort and design (a different burner orifice is used), but propane fuel is more expensive than gas for each BTU of heat.
There have been fewer efficiency improvements in oil furnaces in recent years. Efficiencies are typically in the 80% range. An oil furnace also requires more maintenance than a gas or propane furnace.
If gas costs 70 per therm, then propane could cost no more than 60 per gallon for equivalent heating costs. Oil would have to cost less than 80 per gallon to compete with a super-efficient gas model.
Electric heat pumps are a viable option, especially if you air condition in the summer too. Some new ground-source heat pumps, which draw extra free heat from the ground, have heating efficiencies higher than 300%. Depending on your relative gas and electric rates, using one may be cheaper than gas.
New natural gas powered heat pumps are the ultimate in efficiency year-round. The heating and cooling outputs are nearly totally variable for the greatest comfort. Although a gas heat pump is expensive to install, the monthly utility bills savings can pay back its higher cost over its lifetime.
If you have a good source of firewood, a wood-burning furnace is the least expensive heat. Many of these are dual fuel units. When the wood burns down, a backup gas or oil burner automatically comes on with no heat interruption.
Before selecting any new furnace, have several contractors do lifetime cost analyses using various fuels and for various efficiency models.
Write for Update No. 606 listing the most efficient gas, propane and oil furnaces, electric, ground-source and gas heat pumps, dual fuel wood furnaces, fuel cost comparison charts and do-it-yourself work-sheets. Please include $2.00 and business-size SASE. Write to James Dulley, Los Angeles Times, 6906 Royalgreen Drive, Cincinnati, OH 45244.
Vinyl Siding Can Go Over Wood Shingles Q: My house has wood shingle siding now and some of the shingles are rotten and in poor general condition. I would like to add new vinyl siding. Do I have to remove the old shingles first?
A: You do not have to remove the old wood shingles first. They form a solid base for the vinyl siding and create an extra layer for additional insulation. Replace the badly deteriorated shingles first.
For increased energy efficiency, add 1/2-inch rigid foam board insulation over the old shingles first. Use 2-inch galvanized nails to attach the siding to the wall. Be careful not to nail it too tight to the wall.
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Letters and questions to Dulley, a Cincinnati-based engineering consultant, may be sent to James Dulley, Los Angeles Times, 6906 Royalgreen Dr., Cincinnati, OH 45244.
