I prefer to buy a small electric heater at Wal Mart, and use it to blow heat at my feet. As long as my feet are warm, then I am warm.
Any electric heater will produce up to 3.4 Btu's per watt of input electric. Nothing more. Using a quartz lamp some claim they can make more heat, but they don't. Might be even less heat, because some of the heat is turned into light, not heat.
The only way to make more heat from a electric system is to run a heat pump, and transfer heat. But that is not the subject.
As for saving money, 1 gallon of propane can change in price from one area to another, depending on shipping from the refinery and greed of the retailers among other things. Electric costs also vary from one area to another. Here in Portland Oregon, where they have lots of hydroelectric, it is around $0.10 per KW, and electric heat makes sence.
To get about 80,000 Btu's, you can burn 1 gallon of propane or have an electric heater burn 22 KW. So my cost is $2.20 for electric heat, or about $2.49 currently for propane. To run a heat pump at 40F outside temp, it would take about 8,000 watts to collect and transfer 80,000 Btu's inside. Or about $0.80. At less than 20F, heat pumps become less efficient, however continue to work, and will keep you warm.
Modern R-410 freon heat pumps are even more efficient, and will produce much warmer supply air than a R-22 based system that might be more than 6 years old. The designers have figured out they needed to move more outside air, and the R-410 has a much higher boiling point, so the pressures are higher in both the heating and cooling modes. Of course RV heat pumps change over automatically to electric heat or the furnace at 40F outside air temperature, however home heat pumps can work at 0F by cooling the outside air to -20F discharge temperature, and frequent use of the defrost cycle when the outside coil gets to cold. RV heat pumps do not use the defrost cycle, but would rely on the fan blowing air more than 33F across the coil to remove any frost from it. Thus they just chut off with a built in thermostat at around 38-40F.
When I was living in my RV in Portland Oregon, I had a 120 volt extension cord plugged into the main panel, and my 30 amp RV too. Then I ran one 1,500 watt heater from the extension cord (12 gauge) and from the RV had 2 electric heaters run on 800 watt setting. Also ran the refrigerator on electric too. Never tripped a circuit breaker all winter.
Fred.
