Flue vent older furnace


  #1  
Old 03-15-06, 08:30 AM
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Flue vent older furnace

I have installed an old Reznor ceiling mount natural gas heater in my garage. It's an oldie but goodie. The garage is a 5 car space with a 10' ceiling. The old flue appears to be an 8 inch. Can I reduce this to a 6"?? Was it just old standards why they built them with 8 " flues?? I'd like to use a 6" B vent through the ceiling and out through the roof.
There is a large opening on the front of the heater that probably provides combustion air and also goes directly up the flue. In order not to lose a lot of warm air from the garage, I am planning on sealing off this large opening on the front of the heater and installing a pipe to bring in outside air for combustion.
I know if I asked Reznor, they would probably say can't do.
Is it feasible??
 
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Old 03-15-06, 07:38 PM
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Originally Posted by c21guy
I have installed an old Reznor ceiling mount natural gas heater in my garage. It's an oldie but goodie. The garage is a 5 car space with a 10' ceiling. The old flue appears to be an 8 inch. Can I reduce this to a 6"?? Was it just old standards why they built them with 8 " flues?? I'd like to use a 6" B vent through the ceiling and out through the roof.
There is a large opening on the front of the heater that probably provides combustion air and also goes directly up the flue. In order not to lose a lot of warm air from the garage, I am planning on sealing off this large opening on the front of the heater and installing a pipe to bring in outside air for combustion.
I know if I asked Reznor, they would probably say can't do.
Is it feasible??
How many BTU is the unit itself?

Older equipement was not effcent, so more heat going going to up the flue. I do NOT advisee going down to 6". Also, The large opening in front of the heat is more likey a draft hood, and that MUST be left open.
 
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Old 03-17-06, 01:46 PM
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??

This heater is listed at 120,000 BTU's - Output. It also says the input is 150,000 BTU's. Is it that inefficient?? Or is that normal?? What is a normal input and 0utput for a regular efficiency furnace or heater.
Maybe I'd be better off buying a newer unit??
When I said oldie but goodie, it is listed as built in 1977, but still worked when removed from a Daycare Facility.
Thanks for the info.
 
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Old 03-17-06, 01:50 PM
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Ps

This unit looks just like the newer models. The exchanger tubes and overall design. Would it be cheaper to change out the burner assembly for a more efficient one??
 
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Old 03-17-06, 02:38 PM
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That's alot of heat!

150,000 BTU..

is the garage doors going to be open and closed often?

Where are you out of?

Changing out the burners is not going to make any dffirance in efficeny of the heater.
 
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Old 03-17-06, 07:29 PM
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120,000/150,000 = 80% efficient. More like 70% actual.
 
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Old 03-18-06, 05:14 PM
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I live in Rochester, NY. The temps can get pretty cold here in winter. Doors usually will not be opened while heating.
 
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Old 03-19-06, 06:34 AM
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I'd say you could go low as 80,000/90,000 for the garage. Unless you plan on having the unit off, and turn it on and want a very quick warm up.
 
 

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