Sizing Exhaust Gas Vent on Condensing Furnace.

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Skeeter Power-User Join Date: Jul 2007 Location: Montana, USA Posts: 357 Good Answers: 6	Sizing Exhaust Gas Vent on Condensing Furnace. 04/18/2008 12:30 AM
	When I had an old furnace replaced with a new high efficient type gas furnace, the installer used 2" diameter PVC vent pipe, connected to the exhaust gas blower in the unit, extending straight up about 14' through the roof. When perusing the installation instructions, I discovered that the furnace manufacturer specified that 3" diameter PVC should be use to exhaust combustion gases. I am wondering, if in this case size matters, as to diameter of the vent, since the factory installed exhaust orifice at the furnace is 2" in diameter. __________________ This is it... so live it up!
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shogun7 Commentator Join Date: Dec 2005 Posts: 92 Good Answers: 5	#1 Re: Sizing exhaust gas vent on condensing furnace. 04/18/2008 3:00 AM
	If the mfg said it should be 3" then the contractor should have installed 3 " If he didn't ask/discuss it with you then he should replace it . Call the mfg directly for the consequences of this installation for your family's safty.
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vicini Guru Join Date: Dec 2007 Posts: 588 Good Answers: 13	#2 Re: Sizing Exhaust Gas Vent on Condensing Furnace. 04/18/2008 3:47 PM
	my 100,000 BTU/hr says you can co 28 to 44 feet depending on elbows with a 2". The 3" line is good for 125 to 90 feet. There is a table in the owners manual, and there are tables in the universal vent codes for homes.
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ducon Guru Join Date: Dec 2006 Location: Hop around Toronto, New York & Karachi Posts: 1876 Good Answers: 19	#4 In reply to #2 Re: Sizing Exhaust Gas Vent on Condensing Furnace. 04/18/2008 11:33 PM
	If possible can you post a copy. Thanks __________________ I not only use all the brains that I have, but all that I can borrow. Woodrow Wilson
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miketheboilerguy Power-User Join Date: Mar 2007 Location: South East of Las Vegas just far enough to see the lights but far enough to not hear the coins falling Posts: 282 Good Answers: 8	#3 Re: Sizing Exhaust Gas Vent on Condensing Furnace. 04/18/2008 11:32 PM
	From the Field: I have installed a lot of condensing equipment and I think the 3" requirement is for horizontal runs out the side wall of your house. For horizontal run you can not expect the normal natural draft effect that you get from a vertical rise. I agree that your question is valid but read your installation manual again then call your installer before calling the factory. How is it working for you? Mike __________________ Rule number one; Never ask a question unless you are prepared for an answer that you may not like.
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