Our house is heated with propane. The cost of propane is currently $2.49/gallon. We have a propane fireplace. We have not been using it as a cost saving measure, but I got to thinking I could probably calculate apporximately how much is costs, say per hour to use. What information regarding the firplace do I need to find out. I assume there is not a sticker on it somewhere that says 1 gallon per hour or something. And of the information I need, what can I expect to find on the installed fireplace somewhere vs having to research it? For this question we will assume the fireplace is turned up as far as it can go.
I did find a sticker that says output is 32,500 BTUH. I assume this means 32,500 BTU/H although the “/” is not there.
What sort of a fireplace?
If you mean there is a hearth open to the room, and a chimney open to the sky & a propane fire plays over some rocks which look like logs, well …
The cost of that is huge because, net, it pumps more air warmed by the furnace up the chimney than it sends into the room as heat. In other words, you’d be spending more on gas to achieve a colder house with both running than you would with just your propane furnace running. Even burning 100% cost-free wood in a traditional decorative fireplace will increase your gas consumption & cost to heat the house.
Now if the fireplace you’re describing is designed for heating, the equation changes. I have one which is sealed. Air is drawn through an insulated duct from outside the building directly into a glass-fronted firebox where the flame & fake logs are. From there, the heated air goes up a chimney th the ouside again. No room air ever touches the outside air.
Meantime, room air is blown by a fan around the outside of the firebox & chimney, transferring the heat to the room air. And the fire radiates heat into the room through the glass as well.
For that kind of fireplace, most of the energy in the burned gas ends up in the room, and none of the heat provided by the furnace gets sucked out the chimney.
Once we know what kind of thermal transfers you have, we can start to talk about consumption of gas & how many dollars / hour that translates to.
Propane contains about 90,000 BTU per gallon, so you’ll be going through a bit more than 1 gallon every 3 hours.
Never mind, Q.E.D. beat me to my intended addendum.
We actually have two fireplaces. One can be converted to wood so it has a typical flu and chimney. We can pretty much isolate it from the house by shutting the glass doors and vents. It is designed to get it’s oxygen from outside the house, so while it really won’t heat the house, I don’t think it sucks that much heated air out of the house. We use it for ambience rather than heat.
The second is mainly decorative as well, a zero clearance model that vents ouside. It has glass doors that do not open. I believe it gets it’s oxygen from drawing in room air. It does heat it’s local environment, however. This allows us to keep most of the house cooler than we normally would, because we can be comfortable where we are.