New person here to the forum. Have a question about whether i should tie into my hvac or not. So here goes. Have a 1300 sq ft brick rancher circa 1965 with fireplace at south end of 14 x 22 great room, 8 foot ceilings throughout. Approximately 27 feet to my overhead return vent on my 2 ton package heat pump and 45 feet to the bedroom door on the north side of the home. Fireplace of choice, napoleon nz26 or flame monaco haven't picked between the two. Should i run approx 50 of ductwork to the back bedrooms split in a Y so i can supply heat to both, go up in the attic and tie into my 14 in return line for my heat pump with a gravity fed line from the fireplace or go up in attic and run a gravity fed line and vent it out next to the return vent. Or is this all unecessary because my 14 x 20 return vent is close enough to the fireplace to suck up the heat and send thru the whole house. By the way it is a straight shot from the fireplace to the return vent to the bedrooms. Thanks in advance for all your expert advice
Technical question about tying into HVAC
- Thread starter mildwild61
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Personally, I would start out doing nothing!
Air flow is such a complicated matter that any advice would be subject to many variables - but here is some general stuff....
First, using a central system to spread heat can be very ineffective - for this reason: Your ducts are designed for spreading an output of 30,000 to 70,000 BTU, but the excess heat given off by such a fireplace (other than what would heat that room) would typically be maybe 10-15K BTU. Losses in the ductwork can eat up some of that, so you end up using a lot of power (fan) to move very little heat.
It may be that your existing return does the job to some extent but you have to be careful it does not create a negative pressure on the fireplace and draw CO and soot back into the house...I've seen this happen! It may be that a setup which turns the HVAC fan on for a few minutes when it gets to be a certain temp at the ceiling of that room may do something - but, still, I'd experiment first.
I've had decent results in ranch houses putting a quiet bathroom or kitchen-type fan in the ceiling of the living area and then piping it down to the end of the happ in the attic with a well insulated smaller duct. You could even Y it and dump into two bedrooms - or, leave it alone and use a small oil-filled heater just to add 5 or 10 degrees to the bedrooms.
Hope that helps a bit!
Air flow is such a complicated matter that any advice would be subject to many variables - but here is some general stuff....
First, using a central system to spread heat can be very ineffective - for this reason: Your ducts are designed for spreading an output of 30,000 to 70,000 BTU, but the excess heat given off by such a fireplace (other than what would heat that room) would typically be maybe 10-15K BTU. Losses in the ductwork can eat up some of that, so you end up using a lot of power (fan) to move very little heat.
It may be that your existing return does the job to some extent but you have to be careful it does not create a negative pressure on the fireplace and draw CO and soot back into the house...I've seen this happen! It may be that a setup which turns the HVAC fan on for a few minutes when it gets to be a certain temp at the ceiling of that room may do something - but, still, I'd experiment first.
I've had decent results in ranch houses putting a quiet bathroom or kitchen-type fan in the ceiling of the living area and then piping it down to the end of the happ in the attic with a well insulated smaller duct. You could even Y it and dump into two bedrooms - or, leave it alone and use a small oil-filled heater just to add 5 or 10 degrees to the bedrooms.
Hope that helps a bit!
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