Propane Gas Fireplace or Central Heating

[kbuhagiar]

Hello Folks,

It is a cold rainy evening here in Northern California, sitting in the living room in front of a (propane) gas fireplace, and I am contemplating energy costs.

Our house is heated with propane gas. We usually sit in the living room for TV with the propane fireplace blazing, so the flame may be on for five hours continuously. My first instinct is to think that this is more economical than running the central forced-air heat for five hours. However, the central heat cycles (turns on) only four times an hour, for maybe five minutes each, so total 'flame time' with central heat is 20 minutes per hour.

Stay with me here...so the central heat would burn propane for a total of 100 minutes per evening, while the fireplace would burn propane for 300 minutes.

All things being equal, wouldn't the central heat be cheaper to run? And be more efficient, as it heats the whole house, as opposed to only one room?

Granted, there are additional energy costs associated with the heater fan, but I would think they are insignificant.

Anyway, please feel free to shoot holes in my logic.

 

[acmikee]

how old is your propane heater
you could have propane heat with a heat pump...use the heat pump until it gets below 40deg outside then use the propane to heat below that temp when the heat pump is less energy efficient ..

 

[kbuhagiar]

how old is your propane heater

Two years old

you could have propane heat with a heat pump...use the heat pump until it gets below 40deg outside then use the propane to heat below that temp when the heat pump is less energy efficient ..

We have a Bryant single-stage heat/AC unit, no frills.

 

[MattT]

Stay with me here...so the central heat would burn propane for a total of 100 minutes per evening, while the fireplace would burn propane for 300 minutes.

All things being equal, wouldn't the central heat be cheaper to run? And be more efficient, as it heats the whole house, as opposed to only one room?

Running cost depends on the input BTUs of each appliance. Your gas logs probably use a good bit lower BTUs per hour runtime than the furnace. Your furnace should have a plate on it with the input BTUs on it. The logs might have or it should be in the paperwork if you still have that.

Regards efficiency the gas logs would have to be much less efficient than the furnace to cancel out unnecessarily heating the entire house rather than one room.

 

[Showkey]

Fireplace is maybe 50-70% efficient

Furnace is likely 80-96% efficient depending on model.

 

[Milton Shaw]

If the fireplace is vented, how much warm air is going up the chimney. Gas logs around here are 30K Btu for un-vented and 60k to 90K for vented. So look at BTU ratings and efficient ratings and air loss to determine which is more efficient. I would think the furnace would win after counting air loss plus its safer and the whole house is warm.

 

[finn]

If your furnace has a pvc exhaust and draws outside air for combustion, it’s probably around 94-96% efficient.

The gas fireplace probably has a metal stack, maybe 5 or 6” in diameter and uses inside air. It’s probably 50–60% efficient, as stated.

Draw your own conclusion.

 

[Jackfre]

I'm in Nevada City and had the same central system as you. The equipment was ok, but the install and the ductwork were beyond help. I pulled it and took it all to the dump. I have a Rinnai Energysaver direct vent wall furnace and tankless water heater and mini-split heat pumps. The entire house is zoned. I have never turned the heat on upstairs as he heat rises up the staircase and I like the bedrooms cool anyway. I run those units for cooling in the summer. We are comfortable and H/C the areas we are actually in and are very comfortable that way.
If your central system is in good shape and the ductwork is properly installed, well, you own it now. Your vented gas log or heater is likely in the 60% eff range. What make and model is it? As to which is better, over the next week or so pay attention to how much time you actually spend in areas around the house. Is it worth keeping the place warm bases on how much time you are in those areas? You might find that the best way to improve your comfort is to upgrade your lp heater. Even when I lived in MA I found that my Rinnai Wall Furnace actually became my primary heat. I had the boiler in the basement and could easily heat the place up, but we spent all of our time in the kitchen/family room and the Rinnai handled that very well. The other side of this is the cooling. If you need supplemental cooling then perhaps a mini-split would be the right way to go. Any decisions you make you need to look at the whole picture.