Andrelaplume2, a few comments. You do not state where you live. I have a similar situation. I have a 20 year-old, 1700 square-foot, all-electric, split foyer home in Baltimore. I have been in the house for 5 years. The heat pump is original Trane (we should count our blessings that they have lasted 20-plus years). I have a masonry fireplace in the below-grade family room. I have allergies (dust, pollen, grass, weeds, cats, etc - I get an allergy shot every 3 weeks and have been doing so since childhood). I have been using my fireplace w/one-of-a-kind wood-burning insert to suppliment the heat pump. The insert raises the temperature of the family room from 65 to 72 degrees. The thermostat is in the living room and set at 68. The layout of the house is not open so the heat does not directly go to the second floor living area (where the thermosat is located) and bedrooms, but it does add BTU's to the house and heats the floor of the living room. The fireplace does not affect my allergies. Neither does mowing the lawn. Are you so sure of the effects of wood-burners on your allergies that you write-off the best sources of heat from your masonry fireplace (wood/pellet insert or stoves)? Propane and electric resistance heat are the most expensive sources of heat - and by a large margin as compared to other sources of heat. I run the house fan in the summer only. This does 2 things. First, it helps to move air in the summer (I have ceiling fans also). Second, the wife doesn't know when the A/C compressor cycles off so there is less of a chance that she is playing with the thermostat. You can run your house fan in the winter with your new heat source and see how it works. I find that there is cold-feeling air blowing out of the vents in the winter time when the firepace is going in the family room (there are no return vents in the family room in the ceiling). Is there a return vent in the ceiling near your fireplace? I agree with Bob Brown from the HVAC Forum that your basement heating should be done with your current HVAC system. When you replace your current heat pump, you can increase it's capacity if needed and add ductwork to your basement. My opinions.

First, DO NOT get a ventless system. Many building codes actually outlaw them. I think they all should because the build up of fumes can be dangerous. Therefore, the choice is between a VENTED gas log system and something called DIRECT VENT system. A vented system works pretty much like your present conventional wood burning fireplace. It will provide some heat, but most of the heat will go up the chimney. It is not an energy efficient system. A direct vent system is comprised of a sealed firebox equipped with 2 vents that go up the chimney -- one to exhaust the fumes and the other to bring in fresh air to feed the combustion. It is very energy efficient, and can give off some serious heat. Direct vent systems are costly and take close to a whole day to install, assuming you already have a gas line in place. You really should consider this option if you want more than just the pleasant appearance of a flame. One more consideration: Since direct vent system can get very hot, it's a good idea to get one with a remote thermostat. Otherwise you'll wind up turning the thing on and off over and over again. But if you live in a climate zone where a kit of heat is not the primary consideration, for instance in Florida, a vented gas log system would be a reasonable option. If a really DRAMATIC dancing flame is what you're looking for, I think the Eiklor brand is the gold standard. But it will use a LOT OF GAS, and most of the heat will go up the chimney. So you're almost literally burning money with that one. I'm partial to direct vent. We have one here in North Carolina, and we love it. Make sure you find someone with a good local reputation to do the installation. Otherwise you'll wind up with buyer's remorse.

I think your best bet in getting an answer to your question is to contact the Heatilator manufacturer -- they should have a customer service 800 # -- and ask them. Be prepared with the model # of your unit when you call. But don't be surprised if they give you a vague answer. That could be because they do not want to be sued if something goes wrong. (That's what we were told in a similar situation.) So if you get an answer that is not helpful, the next step would be to go to a gas logs contractor and tell him what you want to do and ask him if he has ever put in gas logs in your kind of setup. That should help you understand what your options are. By the way, it might be helpful to you to search this forum for information on direct vent gas inserts. If you are interested in getting serious heat from your installation, that is the way to go. They are the best technology, highly efficient and have no adverse effect on indoor air quality. But they are expensive.

I recently bought a home that has half a fireplace. It is fairly new home (2006) the previous owners didn't have a clue so builder did like he wanted, looks like to me. The fireplace was never used, which seemed weird, I asked about it and previous owners told me it was a "ventless fireplace like they sell at Lowes". Now I am ready to buy some ventless logs for it (It was never used nor did it have a log set) I check model on tag underside it is Heatilator EL36. The damper is screwed shut and there is no flue/vent pipe to roof, which posed my first question to previous owner. From what I have read, the box is for wood burning, and of course would then need venting. I do not want to burn wood or install flue, don't want to knock wall out of living room. There are also (2) metal strips laying inside on log grate?? My question, can I install a ventless log set in this firebox, even though Heatilator decided not to approve ventless logs for any of their fireboxes? If I have to change firebox, it will be later on before I can buy one, what is good brand of ventless firebox that will fit same opening in wall? Thanks.