Propane Fireplace Log Inserts: Vented vs. Vent-free

We recently had our fireplace flue cleaned and inspected, and it turns out we need a new liner.

Estimates were as high as $8000 and as low as $3200, but it was also recommended that we consider a fireplace log insert (note: not a wood-burning stove insert or entire fireplace insert) since we do not burn a lot of wood (or care to).

The cost seems to be good (about $1500) but we do not have natural gas, so we need to get a propane tank. The price is not a deal-breaker, but I am worried about the smell. Been doing some research, so here is what I found out, followed by a question.

Looking at vent-free and vented.

The “pro” of a vented insert is that there is ample oxygen in the room, less risk/smell, and no need for a new flue liner. The “con” is that the damper must be open so there is less heating benefit and you lose a lot of the already-heated air from the house.

The “pro” of a vent-free insert is that there is much better heat transfer, since you do not need to open the damper, and still no need for a flue liner. The “con” is, even with the oxygen sensor, you have a controlled open flame in your home, and since we will be burning propane, there may be some smell.

So, my question is: do you have any experience with propane log inserts, and what can you tell me regarding the pros and cons I have listed?


I have a vent-free propane log system and there is really no odor associated with it. There is a general “something is on fire” smell that I can’t explain but it is not strong or unpleasant. I have heard the cheaper logs can produce odors so stick with the better known models such as Rasmussen.

I have fairly old and leaky windows. I have heard that, if your home is sealed very well and you have new windows, you should open them a crack or you may get moisture build-up in the room.

Also, you will have the option to rent or buy a tank. Rental looks like a good option up front but you have to buy propane from the company that you rent the tank from…at the inflated rental price. If you buy the tank outright (around $700) you can shop around for propane and possibly get it much cheaper than you would from the rental company.

Same goes for our vent-free natural gas log fireplace. If you didn’t see the flames or feel the heat, you wouldn’t know that it’s on.

I did install a second carbon monoxide / smoke detector just in case, but no trouble in over a year.

One little problem is the thermostat for the heating/AC isn’t too far from the gas logs - about 40 feet. Therefore the rest of the house gets somewhat cold as the thermostat thinks the house is at about 72 F degrees and the heater doesn’t kick on when set at 68 degrees.

Just this afternoon I took an infrared thermometer outside and checked how hot the old chimney was getting. The bricks near the flame and just above it were at about 50 F while the rest of the house was around 33 F degrees. No noticeable heat was coming out of the top of the chimney. I was wondering if I needed to insulate the fireplace better. Seems that it’s not all that necessary.

Yeah, my thermostat is relatively close to the fireplace and registers the increase in temp due to the fireplace. But my entire house at the fireplace level and above heats up. I’m not sure how big your mansion is but maybe you need more than one fireplace :slight_smile:

We are considering a second thermostat for the upstairs. But we’ll probably just live with things as they are now.

As a previous poster mentioned, there can be moisture buildup. I have a 500 sq ft vacation cabin, quite tight, and tried a vent free propane heater. The moisture buildup was so great that I got rid of the heater and went to a vented type. There would be a thin film of water on the floor under some of the furniture.

There is a formula (forget where I found it) that supposedly calculates how much volume is needed in the residence to make a vent free system viable, and it indicated that I should be OK. However, it didn’t work, at least in my case, and I ended up giving the heater away. Hated to, as the vent-free heaters are almost 100% efficient, while the vented types are only around 75%, but I could foresee vast quantities of mold and mildew building up.

Thanks… Do you know if there is a difference between a propane heater and a propane log insert in a fireplace?

I’m not an expert, but I don’t think there would be much difference. If either is non-vented, the results of the combustion have to go into the living spaces, and that’s where the problem lies. IIRC, the amount of moisture put out by the heater I had was on the order of a pint an hour. Certainly enough to be noticeable. You should be able to get this data from the manufacture of the appliance you’re interested in.