Many people recommended against this, some even citing that it may be against code. I don't really care... if that offends you then quit reading now, but if you can swallow that then you may be interested in my experiences so far.
I have a Kozyheat Z42CD zero-clearance fireplace. For those that don't know, this fireplace has an optional ducting kit that comes with flex-duct, a register, and a register mounted blower to pull air from the fireplace which has 2 punch-outs on the top of the shield. The ducting kit really didn't look like it was #1 worth the money, and #2 going to satisfy my needs. But it did tell me one important thing, it must not be that horrible to take heat directly from the fireplace and move it throughout the house like "code" and those that mention "the code" say it is.
So being an independent man that can make decisions on my own without looking at a manual of how to live published by "big brother", I defiantly decided that I was going to duct the heat into my main air-blower system. Plus, I think it is arguable if this is even an "unsealed, solid-fuel, combustion unit" because it draws air from outdoors, and vents the exhaust outdoors, and the doors are sealed except when refueling. So IMHO, this would be classified as a sealed combustion unit and therefore the codes pertain to no HVAC return within X feet wouldn't apply.
What I did:
I took 2 sections of flex duct and connected the 2 ducts to the punch-outs, and combined them into a box-duct that runs into the HVAC air-return. This way the HVAC blower can draw the air out of the fireplace, through the HVAC units, and into the supply duct. The thermostat for the HVAC unit is in the same room as the fireplace. I then pulled the disconnect for the AC compressor unit, turned my thermostat to the "Cool" setting, and set the thermostat to the desired max temperature in the living room. Now, when the living room gets up to temp, the thermostat kicks the blower on and the heat is then drawn out of the fireplace and circulated to other parts of the house.
My experiences with this:
I had heard from many "experts" here that you lose a lot of heat in the duct-work. I think maybe they were just confused. I measured the temp of the air directly out of the fireplace, the temp of the room, and the temp of the air coming out of the ducts. The air right out of the fireplace was 130 degrees, the average room temp of the house was about 66 degrees, and the temp coming out of the supply duct was 88 degrees. Now some may say, "Look, see how much your temp dropped from the fireplace to the supply vent!". But I will counter with the fact that once that air from the fireplace gets into the supply duct it is mixing with 66 degrees air from the supply line, so obviously the temp is going to drop, that was expected. The thing that wasn't expected was exactly how well this has worked to keep the house at a constant temperature.
If I turn the fan off, the living room will stay right around 86 degrees or so (too hot IMHO), and the other rooms will stay around 65 degrees. We can place a fan in our bedroom to blow air out through the hall to the living room, but that only raises the temp to the high 60's or low 70's. That works ok, but it still leaves the bathroom frigid and the other rooms quite chilly. With the HVAC blow turned on, within an hour or so the temp of the whole house (except rooms that we keep closed off) is 72-77 degrees and it is quite comfortable.
Summary:
IMHO, if your fireplace etc has some sort of ducting option, and it is a sealed combustion unit similar to mine, it should serve you well to duct the heat into your main HVAC unit to help circulate the heat throughout the house.
I have a Kozyheat Z42CD zero-clearance fireplace. For those that don't know, this fireplace has an optional ducting kit that comes with flex-duct, a register, and a register mounted blower to pull air from the fireplace which has 2 punch-outs on the top of the shield. The ducting kit really didn't look like it was #1 worth the money, and #2 going to satisfy my needs. But it did tell me one important thing, it must not be that horrible to take heat directly from the fireplace and move it throughout the house like "code" and those that mention "the code" say it is.
So being an independent man that can make decisions on my own without looking at a manual of how to live published by "big brother", I defiantly decided that I was going to duct the heat into my main air-blower system. Plus, I think it is arguable if this is even an "unsealed, solid-fuel, combustion unit" because it draws air from outdoors, and vents the exhaust outdoors, and the doors are sealed except when refueling. So IMHO, this would be classified as a sealed combustion unit and therefore the codes pertain to no HVAC return within X feet wouldn't apply.
What I did:
I took 2 sections of flex duct and connected the 2 ducts to the punch-outs, and combined them into a box-duct that runs into the HVAC air-return. This way the HVAC blower can draw the air out of the fireplace, through the HVAC units, and into the supply duct. The thermostat for the HVAC unit is in the same room as the fireplace. I then pulled the disconnect for the AC compressor unit, turned my thermostat to the "Cool" setting, and set the thermostat to the desired max temperature in the living room. Now, when the living room gets up to temp, the thermostat kicks the blower on and the heat is then drawn out of the fireplace and circulated to other parts of the house.
My experiences with this:
I had heard from many "experts" here that you lose a lot of heat in the duct-work. I think maybe they were just confused. I measured the temp of the air directly out of the fireplace, the temp of the room, and the temp of the air coming out of the ducts. The air right out of the fireplace was 130 degrees, the average room temp of the house was about 66 degrees, and the temp coming out of the supply duct was 88 degrees. Now some may say, "Look, see how much your temp dropped from the fireplace to the supply vent!". But I will counter with the fact that once that air from the fireplace gets into the supply duct it is mixing with 66 degrees air from the supply line, so obviously the temp is going to drop, that was expected. The thing that wasn't expected was exactly how well this has worked to keep the house at a constant temperature.
If I turn the fan off, the living room will stay right around 86 degrees or so (too hot IMHO), and the other rooms will stay around 65 degrees. We can place a fan in our bedroom to blow air out through the hall to the living room, but that only raises the temp to the high 60's or low 70's. That works ok, but it still leaves the bathroom frigid and the other rooms quite chilly. With the HVAC blow turned on, within an hour or so the temp of the whole house (except rooms that we keep closed off) is 72-77 degrees and it is quite comfortable.
Summary:
IMHO, if your fireplace etc has some sort of ducting option, and it is a sealed combustion unit similar to mine, it should serve you well to duct the heat into your main HVAC unit to help circulate the heat throughout the house.
