How much to run your gas fireplace.

[Snagglefoot]

I recently serviced my Regency gas fireplace and calculated how much per hour to run it.

Here is the formula, firstly for propane.

Fireplace heat rating from name plate in BTU/hr
Converstion factor for BTU per gallon of propane. 91,500 BTU / gallon
Price per gallon of propane, all in including delivery and taxes
Efficiency of fireplace. Usually .6 if it draws air from the room and 0.7 if it draws air from outside.

Here is an example.

Fireplace rating = 30,000 BTU per hour.
Conversion factor = 91,500 BTU per US gallon
Price per gallon = $2.50
Efficiency = 0.6

30,000/91,500 x 2.5 /0.6 = $1.37 per hour.


Now, if the fireplace is being controlled by a wall thermostat, once it reaches steady state, the fireplace might run only say 1/3 of the time which reduces the cost to $ 0.46 per hour.

For natural gas delivered for $/mcf, the conversion factor is 1,000,000 BTU per mcf.
The price per mcf might be say $10 or whatever they charge you. The efficiency is 0.6 or 0.7.

For the example we have:

30,000/1,000,000 x 10 / 0.6 = $0.50 per hour. If it runs only 1/3 the time, the cost is $0.17 per hour.

Hope that helps. Lemme know If I missed something. Snag.

 

[Hall]

Efficiency of fireplace. Usually .6 if it draws air from the room and 0.7 if it draws air from outside.

What does that mean ? Isn't efficiency based on output ? We had a vent-free gas fireplace in our old house and my HVAC neighbor always pointed out that we should use it as much as possible since it's (almost) 100% efficient. All of the heat produced stays inside, not vented outside.

 

[Snagglefoot]

What does that mean ? Isn't efficiency based on output ? We had a vent-free gas fireplace in our old house and my HVAC neighbor always pointed out that we should use it as much as possible since it's (almost) 100% efficient. All of the heat produced stays inside, not vented outside.

There should be a metal plate somewhere with the efficiency. Even my condensing propane boiler is only 95% efficent.

So if the plate on a fireplace says 60% efficient, 40% is lost out the exhaust.

For a vent free fireplace, yes it would be 100% ( confirm it with the plate). What you trade off is you will be breathing in the small amount of whatever is in the exhaust. ( which is not much), no more than what comes off a gas cooking stove.

 

[97prizm]

I recently served my Regency gas fireplace and calculated how much per hour to run it.

Here is the formula, firstly for propane.

Fireplace heat rating from name plate in BTU/hr
Converstion factor for BTU per gallon of propane. 91,500 BTU / gallon
Price per gallon of propane, all in including delivery and taxes
Efficiency of fireplace. Usually .6 if it draws air from the room and 0.7 if it draws air from outside.

Here is an example.

Fireplace rating = 30,000 BTU per hour.
Conversion factor = 91,500 BTU per US gallon
Price per gallon = $2.50
Efficiency = 0.6

30,000/91,500 x 2.5 /0.6 = $1.37 per hour.


Now, if the fireplace is being controlled by a wall thermostat, once it reaches steady state, the fireplace might run only say 1/3 of the time which reduces the cost to $ 0.46 per hour.

For natural gas delivered for $/mcf, the conversion factor is 1,000,000 BTU per mcf.
The price per mcf might be say $10 or whatever they charge you. The efficiency is 0.6 or 0.7.

For the example we have:

30,000/1,000,000 x 10 / 0.6 = $0.50 per hour. If it runs only 1/3 the time, the cost is $0.17 per hour.

Hope that helps. Lemme know If I missed something. Snag.

Are there more efficient fireplaces? Or is the value given fairly standard? How does this cost compare to the processed logs for regular fireplaces?

 

[FZ1]

I recently served my Regency gas fireplace and calculated how much per hour to run it.

Here is the formula, firstly for propane.

Fireplace heat rating from name plate in BTU/hr
Converstion factor for BTU per gallon of propane. 91,500 BTU / gallon
Price per gallon of propane, all in including delivery and taxes
Efficiency of fireplace. Usually .6 if it draws air from the room and 0.7 if it draws air from outside.

Here is an example.

Fireplace rating = 30,000 BTU per hour.
Conversion factor = 91,500 BTU per US gallon
Price per gallon = $2.50
Efficiency = 0.6

30,000/91,500 x 2.5 /0.6 = $1.37 per hour.


Now, if the fireplace is being controlled by a wall thermostat, once it reaches steady state, the fireplace might run only say 1/3 of the time which reduces the cost to $ 0.46 per hour.

For natural gas delivered for $/mcf, the conversion factor is 1,000,000 BTU per mcf.
The price per mcf might be say $10 or whatever they charge you. The efficiency is 0.6 or 0.7.

For the example we have:

30,000/1,000,000 x 10 / 0.6 = $0.50 per hour. If it runs only 1/3 the time, the cost is $0.17 per hour.

Hope that helps. Lemme know If I missed something. Snag.

Is a flu open to the outside?

 

[IndyIan]

What does that mean ? Isn't efficiency based on output ? We had a vent-free gas fireplace in our old house and my HVAC neighbor always pointed out that we should use it as much as possible since it's (almost) 100% efficient. All of the heat produced stays inside, not vented outside.

Yikes, unless you have a very air leaky house, or a big heat recovery unit(that you actually run), at the very least you would have serious moisture build up, but also the other combustion by products aren't good for you either!

 

[thastinger]

I recently served my Regency gas fireplace and calculated how much per hour to run it.

Here is the formula, firstly for propane.

Fireplace heat rating from name plate in BTU/hr
Converstion factor for BTU per gallon of propane. 91,500 BTU / gallon
Price per gallon of propane, all in including delivery and taxes
Efficiency of fireplace. Usually .6 if it draws air from the room and 0.7 if it draws air from outside.

Here is an example.

Fireplace rating = 30,000 BTU per hour.
Conversion factor = 91,500 BTU per US gallon
Price per gallon = $2.50
Efficiency = 0.6

30,000/91,500 x 2.5 /0.6 = $1.37 per hour.


Now, if the fireplace is being controlled by a wall thermostat, once it reaches steady state, the fireplace might run only say 1/3 of the time which reduces the cost to $ 0.46 per hour.

For natural gas delivered for $/mcf, the conversion factor is 1,000,000 BTU per mcf.
The price per mcf might be say $10 or whatever they charge you. The efficiency is 0.6 or 0.7.

For the example we have:

30,000/1,000,000 x 10 / 0.6 = $0.50 per hour. If it runs only 1/3 the time, the cost is $0.17 per hour.

Hope that helps. Lemme know If I missed something. Snag.

I have one house that is propane and one house that is NG. I own the tank at the LP house.
BLUF is that NG isn't cheaper per BTU than propane is. The actual gas is much less expensive but once they utility adds in all the distribution charges, meter charges, taxes, environmental charges etc. it is the same cost as LP on a BTU basis, of course I prepaid all of the infrastructure costs for the LP up front.

 

[IndyIan]

There should be a metal plate somewhere with the efficiency. Even my condensing propane boiler is only 95% efficent.

So if the plate on a fireplace says 60% efficient, 40% is lost out the exhaust.

For a vent free fireplace, yes it would be 100% ( confirm it with the plate). What you trade off is you will be breathing in the small amount of whatever is in the exhaust. ( which is not much), no more than what comes off a gas cooking stove.

I had assumed that most gas fireplaces were condensing, but after talking to a guy in the business, apparently that's not common at all. He says they are a bit of a backup heat source, but primarily sold for the aesthetics.

I think almost anywhere, if its available, NG wins for cheapest BTU per dollar, except maybe in Quebec or Manitoba where super cheap electricity might let a heat pump (in ideal temperatures) come close. A NG condensing boiler with a hydronic system is usually the most efficient heating system in terms of fuel, but pretty expensive to install for a small house.

 

[thastinger]

Are there more efficient fireplaces? Or is the value given fairly standard? How does this cost compare to the processed logs for regular fireplaces?

Yes there are, some of the actual wood stoves are in the 90s, they draw combustion air from outside the house.

 

[Snagglefoot]

Is a flu open to the outside?

Yes.

 

[IndyIan]

Are there more efficient fireplaces? Or is the value given fairly standard? How does this cost compare to the processed logs for regular fireplaces?

NG usually beats wood stoves fueled with split and delivered firewood, for cost per btu of actual heat delivered.
In the average cord of hardwood you get 20-24 M btu at $300-400/cord So right away you are paying more for fuel and its not as efficient as a good condensing furnace or hot water tank.

Now a decent wood stove and chimney is like $3-4-5k, and goes for 30-40+ years with some basic maintenance.
Probably getting 50-60% of heat out of the wood would be running it well.

In 20 years our stove has needed the glass and door gaskets reglued a couple times, 6 fire bricks replaced, and 2 secondary air tubes replaced, so like $80 in maintenance. I clean the chimney every couple years with a brush on threaded rods from inside, and once in a while I check in attic to see how the whole roof is doing including the chimney. So far no rust or loose pieces.

It doesn't really pencil out if you are buying wood and have NG available, but with free trees and only $4+/gal propane available, its a cheap hobby that heats your house for a couple hundred bucks a year.

 

[FZ1]

Yes.

Losing some conditioned air when the fire ain't burnin' if the flu remains open.

 

[Hall]

Yikes, unless you have a very air leaky house, or a big heat recovery unit(that you actually run), at the very least you would have serious moisture build up, but also the other combustion by products aren't good for you either!

No moisture "issues" at all, besides some add'l moisture in the winter isn't a terrible thing. Combustion byproducts ? No idea.... House seemed pretty air-tight too, in fact, after we replaced the definitely leaky old basement windows with glass-block, that winter, the fireplace insert wouldn't stay lit. My neighbor told me to open one of the vents in one of the glass-block windows to let more air (oxygen) in (???) and that worked.

Vent-free inserts are pretty common here too.

 

[2strokeNorthstar]

Wife stopping complaining > Price to run gas fireplace

 

[mk378]

The nameplate rating is input BTU, a theoretical number based on the designed flow rate of gas and the heat realized were the fuel to be completely burned and the resulting water vapor condensed.

The gallons or cubic feet of fuel per hour entering the appliance, and thus the operating cost per hour can be computed directly from the input rating.

BTU delivered to the room as usable heat is input * efficiency.

Pilot lights can use a significant amount of gas during standby.

 

[Snagglefoot]

Yes.

Actually it exhausts up a sheet metal chimney. The front of the gas fireplace has a sealed glass front and the air intake is at the front of the fireplace below the propane burner. There’s very little air movement with the furnace off. By flue, I took that to mean it vents outside as opposed to some who had a non-venting gas fireplace. There on no moving flue like in a wood burning fireplace.

 

[Snagglefoot]

Yes.

Actually it exhausts up a sheet metal chimney. The front of the gas fireplace has a sealed glass front and the air intake is at the front of the fireplace below the propane burner. There’s very little air movement withe furnace off. By flu I took that to mean it vents outside as opposed to some who had a non venting gas fireplace. There on no moving flu like in a wood burning stove or chimney for it.

The nameplate rating is input BTU, a theoretical number based on the designed flow rate of gas and the heat realized were the fuel to be completely burned and the resulting water vapor condensed.

The gallons or cubic feet of fuel per hour entering the appliance, and thus the operating cost per hour can be computed directly from the input rating.

BTU delivered to the room as usable heat is input * efficiency.

Pilot lights can use a significant amount of gas during standby.

All good except that age old error of rating gas appliances in “ BTU”. It’s actually “BTU per hour”.

 

[Leo99]

Sounds about right. I run my gas fireplace in the winter and don't notice much of a difference in my gas bill between the winter months when I run it vs don't run it.

 

[FZ1]

Yes.

So the flu closes when the fireplace is not burning?

 

[Cropduster172]

I have a ventless "see through" fireplace that is both in our living room and our family room...
No vent. It warms the downstairs of our house depending on outside temperature, 3-4 degrees in 20-30 minutes. It was 18 this AM. I keep the thermostat at 68. Within 30 minutes it was 70. Problem is, the thermostat for the entire house sits 12-15' from the fireplace...so upstairs could be 63....and our master bedroom often is in winter, but downstairs is 70-72. Never had a C02 detector trigger and I just bought a digital readout one... always 0.
It's a NG Petersen Real-Fyre with an adjustable flame remote. I like it.