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badata2d · Jan 2, 2008, 09:11 AM

I recently purchased a new construction house that uses propane for heat. It has two units a Trane 80 and Trane 90. They service two different floors in the house. We keep the heat at 68% at it's highest and live in the Northeast so it's generally pretty cold in the winter. The house is a 3,400 sq ft colonial.

For just December we went through 400 gallons of Propane ! That's $1,000+ for a single month of heat. I've had natural gas and oil in the past with larger homes and never spent close to that for a single month.

Does that seem excessive for those with Propane? I'd like to get an idea before I start spending $$ bringing in people to start looking at the system.

Thanks... eric

asking · Jan 2, 2008, 09:51 AM

I have a smaller house than you, and keep the temperature lower as much as possible because, yes, that would be typical if I were doing what you are doing and living where you are. It's awful! I also have two heaters, one for upstairs and one for downstairs. I keep the one downstairs set for 59 degrees at night and about 61 during the day and go around in a jacket. The upstairs is where my office is, so I set it higher, maybe 64ish. I burn wood when I have lots of people in the house and want to warm it up to 68. I live in California, but it's been in the low 30s most nights. I think turning down your thermostat and bundling up is the only solution.

Also, of course, anything you can do to insulate the house. Thick curtains? Check the weatherstriping on your doors. If it's off kilter a little, that can make a huge difference. Usually, there are little screws you can loosen to adjust the angle so it seals better.

therinnaiguy · Jan 2, 2008, 10:19 AM

Make sure your gas pressure is correct. Hire a gas technician who owns a Combustion Gas Analyzer. This tool will give you an instant readout of each systems efficiency. Why did the contractor go with the 80% and not both 90"s?

Anyway, knowing what they are running for efficiency, you can calculate how many Btu's you are consuming to heat your home. In Northern Vermont, a new home 4-star or better would require a heat-loss of about 68,000 output. Add 10% to get the input for the 90% system and 20% for the 89% unit. Lets say 80,000 BTU input for the house. For every hour of operation, this furnace will use less than one gallon of propane (92,500 BTU in one gallon of propane). . 864 of a gallon to be exact. Your furnace will not run more than 6 times in one hour and you may have to add an hour meter to the gas valve wiring to see how many hours in a month it operates.

Assuming that your total system uses .86 gallons per hour times 24 hours times 30 days per month equates to 619 gallons. You know that it uses only 400 per month so you average a little more than 1/2 gallon per hour (47,000 Btu's). Not Bad!

Propane equipment being very efficient is less expensive to install than oil, however it will cost you more to operate than oil or natural gas. If I were you, shop around for a propane company who can provide you with the same product at a lower cost. Add more insulation where ever you can and only heat the areas of you home where you live. Keep all other areas at a lower heat not more than 5 degrees less than the main areas.

hvac1000 · Jan 2, 2008, 10:22 AM

Propane costs big$$. A heat pump setup would have been a better deal for you. If you can afford to buy a 3400 sq ft house you also have to pay to heat it.

Many folks in our area have already started to down size there housing because of taxes and utility bills.

asking · Jan 2, 2008, 11:40 AM

Originally Posted by therinnaiguy

only heat the areas of you home where you live. Keep all other areas at a lower heat not more than 5 degrees less than the main areas.

This was a fascinating answer.

Can you explain why it's better to keep unused areas no more than 5 degrees cooler? I can see that you would lose less heat to these areas if they are very cold (because of a higher temp. differential), but does that make up for the cost of heating areas no one is using?

I have a guest room that is normally empty and which is separate from the rest of the house and also less well insulated, so I don't heat it at all. At times, it gets extremely cold in there. Is that a bad idea?

badata2d · Jan 2, 2008, 11:50 AM

Originally Posted by asking

This was a fascinating answer.

Can you explain why it's better to keep unused areas no more than 5 degrees cooler? I can see that you would lose less heat to these areas if they are very cold (because of a higher temp. differential), but does that make up for the cost of heating areas no one is using?

I have a guest room that is normally empty and which is separate from the rest of the house and also less well insulated, so I don't heat it at all. At times, it gets extremely cold in there. Is that a bad idea?

I am very curious about this as well. The third floor of my house is my office which I just shut off the zone on weekdays. I find it stays between 50-55 even when it is 20 out because of heat leaving from the 2nd floor. I would have to imagine that is saving me more money than paying to have it at 63 degrees, which would be within 5 degrees.

Thanks to everyone for all of the fantastic answers!

therinnaiguy · Jan 2, 2008, 12:02 PM

Heat seeks cold, if one area of your home is 70 and the other area is 60, the heat will move from the warmer area to the cooler area at a greater rate than if it were 70 and 65. This air flow does a couple of things, air movement over the skin even if warm feels cool, and you have to replace the heat lost from the warmer room at a greater rate.

If you can separate rooms by a door, you can get by lowering the thermostat in the unused areas more than the 5 degrees I recommend.