macv - he was talking about using isokern for our other 5 fireplaces (2 in basement, one screened porch, one den, one keeping), not the fireplace in the small study, which is 12 x 12, where there is currently not one. I think he was talking about the depth difference between traditional masonry and isokern standard - he did say the fireplace was 2 feet (?), and the back to back isokern (in keeping and screened porch) is 4 feet. As one is on an interior wall and one is a back to back fireplace, we don't have the option of pushing the chimney outside, and our rooms are not very big so the 2 feet for the fireplace and 20 inches for the hearth make a difference I am finding! I think the plans are getting very close to being finalized and we were able to put two doors in the study (one from entrance hall and one connecting den and study with walk through butler's pantry like bar in the short hallway, which is a great place for the bar which we have been struggling with). I am going to have an interior designer look over the plans to be sure about room size as far as furniture placement, sight lines, flow, etc. and I will have her weigh in about the fireplace as well. How deep is a traditional b-vent? If we just have to find a foot for it that is less problematic. . . The hearth doesn't bother me as you can easily push an ottoman right up to the hearth (it will not be raised) if you need to. I still would like to have one but now that the room is not a dead end I feel much better about it not being necessary.

The hearth must be composed of noncombustible material. There is no wiggle room around that. If a manufacturer of a synthetic brick you are interested in cannot claim IN WRITING that the product is noncombustible and suitable for the purpose you intend, I would not use it, because you incur a safety risk, which may be compounded by building code violation risk. Your mantle can be made of wood so long as you observe the required clearances, the distance between the edge of the firebox and the edge of the mantle, which must be bridged by noncombustible material. Prefab units typically specify the clearances in their manuals. If you're planning a custom-built unit, you need to rely on the local building codes and the expertise of your installer. You might want to post your question in hearth.com for further comment.

We have natural gas here, and installed a Valor direct vent fireplace, several years ago.It has been trouble free since installation. It has saved us a tremendous amount of money (Utility bill-wise) for both electricity as well as gas. It heats the whole downstairs of our 2700 sq ft house, so we rarely use the forced air heating system with its big burners and fan. (We use it once in a great while) to heat the upstairs master bathroom, but eventually I hope to install another direct vent fireplace in the master bedroom. The gas fireplace is controlled by a hand-held remote control with a built in temp sensor, You can put the remote control next to your easy chair, (or wherever You Like), it will turn the fireplace up/down as needed to keep the temperature set to whatever is set on that remote control. Valor is one of the few direct vent fireplaces that is able to turn the fireplace from full on to nearly full off from the remote, most fireplaces will only go down about 20% or so. You can turn the fireplace off from the remote too. Good luck on the hunt!!! I'm sure Valor makes fireplaces for LP too. Here's a picture of the fireplace. Gary

Although these units have very few moving parts, they do need periodic preventive maintenance, probably best done by a professional. Ours, a different brand, is still too new to need any maintenance -- preventive or otherwise. How often you do it depends in part on how much you use it, assuming that certain components get dirty and need cleaning out. I think once a year is probably too often unless you use it as a main source of heat. But I haven't anwered your question. I think it needs diagnosis by a professional who knows exactly what to do to troubleshoot. Here's my speculation: If the thing sometimes stops firing spontaneously, and then goes back on spontaneously, that suggests that the vent that provides oxygen to feed the combustion may be partly clogged. That should not happen if the right kind of cap was installed on the chimney, but it's still possible after a period of time. If you can easily get to the chimney top without risking life and limb, go up there and see if anything obvious is clogging it.