Propane furnace vs. heat pump operating costs

[John_Canfield]

Since we are parked for most of the winter with the coach in 'storage' in our RV port, I was thinking about the operating expense of the heat pump vs. the propane furnace.

We keep the thermostat set at about 63 and in the electric heat mode. Most of the time, the heat pump is running except when we dip down into the 20s and 30s at night.


Obviously I can set the thermostat much lower and save money, but I wonder if it would be less expensive to use the propane furnace exclusively? Has anybody done the math?

[John_Canfield]

Since we are parked for most of the winter with the coach in 'storage' in our RV port, I was thinking about the operating expense of the heat pump vs. the propane furnace.

We keep the thermostat set at about 63 and in the electric heat mode. Most of the time, the heat pump is running except when we dip down into the 20s and 30s at night.


Obviously I can set the thermostat much lower and save money, but I wonder if it would be less expensive to use the propane furnace exclusively? Has anybody done the math?

[smlranger]

Happy New Year, John.

I've not done the math but have asked myself the same question. Our rig is stored outside and I keep the thermostat set at about 55 F. I know the little dial on the electric meter spins pretty fast when the heat pump is on and the cost per KWH with our local co-op is fairly high. I can also fill the propane tank when I do my monthly coach exercise run to a shopping mall.

However, what I've settled on is one of those oil filled electric heaters set in the galley area. On it's lowest setting, I can maintain 55- 56 F in the coach.

Obviously, this doesn't help warm anything else if the coach is not winterized. Mine is, so the little heater just keeps things inside from exposure to freezing temps.

[John_Canfield]

Hi Gary and Happy New Year to you

I think I want the propane furnace running so the basement compartments get at least some heat, otherwise the portable heater sounds like a great idea. I've been concerned about my windshield cleaner and other liquids I keep in the little outside cubby-hole compartments freezing and making an ugly mess. Surprisingly this has never happened (yet.) If it looks like we are going to get into the teens here, I probably should remove anything that could freeze in an unheated compartment.

[KIX]

That will be a very difficult problem to get accurate. However, here are some conversions that will allow you to make the calculations yourself.
1 gal. propane contains 91,500 BTU's
1 Kw of electricity contains 3412 BTU's

So 26.82 Kw = 1 gal. propane...speaking BTU content.
If electricity is $.10/Kwh it would take $2.68 worth of electricity vs. 1 gal. of propane which may be $3.00. Your results may vary.
Now you'll have to make some assumptions.
Which fuel and heating method is more efficient? What are the taxes on each fuel? What's it going to cost you to drive your rig to get more propane? As temps fall heat pumps become less efficient. There are just too many variables to make a non-laboratory accurate comparison.
My thought is: if you live in a warm climate and have few heating days use what's convenient.....if you live in a climate with many heating days then start doing your homework if you really want an answer. Good Luck.
Happy New Year!

[JWatkins]

I think you have to be aware of the hours on your heat pumps and the potential for repair costs as well. I think the propane solution sounds like a better one, even if it costs a little more. A ac/heat pump repair will cost a lot.
Joe

[Ray,IN]

If KIX will allow me to add some comments to his accurate reply; most RV furnaces are around 60-65% efficient, electric is virtually 100% efficient for heating. Find the input BTU for your LPG furnace then divide it into the BTU content of one gallon of propane 91,501-91,690(depending on source), if you use butane 102,032. Factoring in furnace efficiency, the propane multiplier is 22 X the cost of electricity per KWH, of course butane is different. Compare that result to the cost of LPG per gallon.
Some interesting LPG sites are: altenergy.com
propane safety
engineeringtoolbox.com

[jimandsue60]

John, if your coach is in storage, why don't you winterize it? If you are planning to use it now and then, I understand your question.

I would have a local propane company deliver a larger external lp tank and tap into the rv system. Keep the temperature at a nominal setting that will prevent the coach from freezing. Your rv tank will remain full for travels and you might get a discount for buying bulk.

Jim

On edit, let the heat system run on propane and leave the basement system stagnant. My thought is that the basement system is a bit more finicky and more expensive to repair or replace.

[John_Canfield]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by jimandsue60:
John, if your coach is in storage, why don't you winterize it? If you are planning to use it now and then, I understand your question.--snip-- </div></BLOCKQUOTE>Jim - we do use the coach every so often in the winter, so I don't want to 'pickle' it.

Thanks to everybody for the great responses!

[Shuffster]

There has been some good input in this discussion, but I must point out that heat pumps are rated on COP (co-efficent of performance). Typical air to air heat pumps run in the 2.0 to 3.0 range, Meaning that compared to resistant heat, the heat pump can provide 2 to 3 times the heat as just heating up a piece of wire.

This would put the economy of using the heat pump, way beyond using propane. (unless Texas still has 59 cent propane!)

Finally, as I understand the house thermostat, if the heat pump fails to maintain inside temperatures within 5 degrees of the set point, that the propane furnace will operate.

The heat pump is clearly the economic choice, but the warmth of the gas heat is more comfortable when the outside temps approach freezing.

Tidings from Idaho

[SCVJeff]

I thought the heat pump basically quits working around 40 degrees or so, yes? But even if it did work, there is no circulation through the basement anyway, so wouldn't that be the same as an oil can?

[ichn2go]

John/Gary,,why keep your thermostat set so high?
I too have the oil filled radiator and set on low it does a good job.

I keep my thermostat on 45, knowing this will keep the compartments warm in a freeze. John , I can't tell you which is cheaper, but I can tell you the cost of everything has sky rocketed.
Just pump gas at the Marina $3.47 per gal. First I pumped in two years, so you can see why I am not fishing. How many miles will we travel in the MOHO this year? I just grin and bear It. Happy New Year to all

[John_Canfield]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by SCVJeff:
I thought the heat pump basically quits working around 40 degrees or so, yes? But even if it did work, there is no circulation through the basement anyway, so wouldn't that be the same as an oil can? </div></BLOCKQUOTE>Jeff - the heat pump's lower operating limit depends on the humidity I have decided. When we wintered in Florida, we would have it freeze up with the temp in the 40s. We've also had it work with temps in the 30s in a drier climate.

I think the best solution for us is to lower the thermostat to about 55 and leave it in the electric heat position. One thing I just thought of is the heat pump I believe will still dehumidify unlike propane heat.

Hi Jimmy - I don't think we are going to put as many miles on the coach this year as we did last year. We were spending almost a thousand bucks a month on fuel alone last summer.