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cvsmoove · Apr 4, 2009, 10:15 AM

I am looking to replace my hvac unit. I have had one installer tell me I need 2 pvc lines, one to bring in combustion air and one to vent out. Another installer told me that the intake is not necessary. The equipment is Goodman 95%, variable speed fan.
How important is this?
Chris

Joshdta · Apr 4, 2009, 10:22 AM

Depends on the size of the room your furnace is in and what is located neer it

Joshdta · Apr 4, 2009, 10:22 AM

If you have plenty of free space I would just go with 1 pipe system

cvsmoove · Apr 5, 2009, 12:47 PM

Originally Posted by Joshdta

If you have plenty of free space i would just go with 1 pipe system

Is there an advantage to have two? I was told that It would improve air quality. Does it require less humidification? I live in Wisconsin, so it gets pretty cold.

letmetellu · Apr 5, 2009, 01:06 PM

I have never installed a Goodman 95% but I have others and I always use the two pipe venting system. I am including a site that you might read about to help make up your mind.

http://www.djsonline.com/gmhspecs.pdf

cvsmoove · Apr 5, 2009, 01:41 PM

Originally Posted by letmetellu

I have never installed a Goodman 95% but I have others and I always use the two pipe venting system. I am including a site that you might read about to help make up your mind.

http://www.djsonline.com/gmhspecs.pdf

Is there a formula for determining if I need 2" or 3" venting? I have a 2" pipe on my current furnace, about 22' length w/ 1-90 and 2-45 degree turns to outside wall. This does not include the outside piping. I would like to use this if I can, but don't want to cheap out at the risk of performance.

Joshdta · Apr 5, 2009, 01:49 PM

How many btu's is your new furnace going to be?

Joshdta · Apr 5, 2009, 01:50 PM

You should be able to go up to 30 foot on a 100,000 BTU

cvsmoove · Apr 5, 2009, 01:53 PM

Originally Posted by Joshdta

you should be able to go up to 30 foot on a 100,000 btu

92000 btu's. So the sxisting pipe should be OK?

Joshdta · Apr 5, 2009, 01:54 PM

Yse I would say so inless goodman has some special requirements. Do you have 1 pipe or 2 now?

Joshdta · Apr 5, 2009, 01:55 PM

Usually you only need 3 in pipe for 125,000 BTU furnaces or inles you are going over 45 feet or so

cvsmoove · Apr 5, 2009, 01:59 PM

Originally Posted by Joshdta

Yse i would say so inless goodman has some special requirements. Do you have 1 pipe or 2 now?

1 pipe, Do you have an opinion about Goodman quality?

Joshdta · Apr 5, 2009, 02:02 PM

As for myself I have never had much good luck with the goodman of janitrol brand. I have never installed 1, just serviced them.

Joshdta · Apr 5, 2009, 02:19 PM

Is goodman the only brand you were considering? The 95% eff is good as is the varable speed, how is the warranty on the unit? A varable speed fan will run you around $450 if it goes bad

KISS · Apr 5, 2009, 02:26 PM

I just saw this post. Use a concentric vent kit: http://www.htproducts.com/literature/lp-166.pdf

Th install won't look ugly. It's looks like one pipe out of the wall. No U bends or large pieces of pipe.

Drawing cumbustion air from outside is a good idea. When this is is used, the cumbustion chamber is isolated from the house.

mygirlsdad77 · Apr 5, 2009, 02:46 PM

Originally Posted by cvsmoove

1 pipe, Do you have an opinion about Goodman quality?

I have had great luck with the newer goodmans. 2" is good for under 105,000 input. 105 and over requires 3". Also, exhuast slope is very important. Goodman is one of the highest eff forced air furnaces out there. And purchase price is very reasonable. I don't think you will regret the choice, however, all furnaces will work only as good as the install. If you are doing this yourself, I would suggest two pipes, intake and exhuast. Follow the venting directions very closely. This will allow you to sleep better at night knowing that you have done everything as professionally as possible. Does the board on your goodman have a spot on it to switch from 1st stage to 2nd stage. This will be a very small set of three switches. One will be for blower on time. One will switch from 1 to 2 stage, and one will switch from auto to 5 minute switch over(from 1st to 2nd stage)

wmproop · Apr 5, 2009, 08:17 PM

just a thought

don`t know where you are getting your furnace,but if you are not a qualified/certified /licensed contractor,you probably won`t have a warranty on a furnace you install yourself.the parts,even if you know how to install can get pretty expensive if bought with no warranty,, especially that variable speed fan motor
Ive not been convenced that they are worth th extra bucks

just something to consider

cvsmoove · Apr 7, 2009, 04:08 PM

Originally Posted by wmproop

just a thought

don`t know where you are getting your furnace,but if you are not a qualified/certified /licensed contractor,you probably won`t have a warranty on a furnace you install yourself.the parts,even if you know how to install can get pretty expensive if bought with no warranty,,,especially that variable speed fan motor
Ive not been convenced that they are worth th extra bucks

just something to consider

I had considered doing it myself, but decided to go with a local licensed contractor for the very reasons you gave, Thanks

Joshdta · Apr 7, 2009, 04:17 PM

Did he agree to use the 1 vent or did you add a second pipe?

mygirlsdad77 · Apr 7, 2009, 04:18 PM

Great decision. Hope all goes smoothly.