This spring I moved a high efficiency furnace. The air intake and air exhaust vent/intake are outside, at the time I just cut off the PVC air lines and now that it is time to hook everything back up I have forgotten which is which? one snorkels up and one elbows down, which should be the intake and which should be the exhaust? And my second question: Do I have to use Scd 40 2.5″ PVC, I have several twists and turns to make to route this out and a flexible length of something would really help. (I’m well within the overall distance/bend limit) does it really need to be PVC? and why? As always, thanks in advance.
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Wow......I can't believe it! I was going to start a new thread tonight titled "Death by DIY". I was at a customer's house today doing some home maintenance and I happened to notice some work by the ex-husband. He decided that the high efficiency furnace should be vented through the side of the house instead of the roof. He used flexible dryer vent pipe with duct tape and hose clamps. The pipe was riddled with holes. He terminated it with a louvered dryer vent cap! AND he vented it underneath a bedroom window!
They don't have a carbon monoxide detector. The customer also happens to be my sister-in-law and my wife says she's been complaining of headaches!
What is the thought process in performing this kind of home improvement! AND it's in a half-million dollar house!
AAAAAAAAAAGGGGGGGGGHHHHHHHHHHHHH!!!!!!!!!!!!!!!!!!!!!!!!
jocobe
AND he vented it underneath a bedroom window!
Depending on the distances, that can be ok! Most (all?) 90+ high effienciy furnaces can be side wall vented. You need to get the manufacturer's installation instructions and follow them
But the flex vent with holes ain't right! (Small holes in a naturally drafted flue and in some 80+ flues are actually probably not a problem - the natural draft of the hot flue gases through the flue will suck air intpo the flue through small holes. OTOH, why tempt fate?
A 90+ furnace draft inducer pressurizes the flue, do flue gases and CO will get out through those holes!
And, of course, bozo wotrk is bozo work.
Yes it needs to be PVC because of the acidic natute of the condensation from the flue gases.
You need to get the ionstallation instructions for that brands and model of furnace and follow them to the letter.
Don't screw around with this one, you can cause CO problems or cause premature failure of the furnace, and they aren't cheap.
Thanks. I guess PVC it is. Corrosion,,, on several levels should have known that! I guess that is why I asked, a faint little bell going off waaaay back in my head. I should have made my 1st question more clear, I am re-hooking up what was there and done by a pro (I assume he did it right). I just can't remember if the exhaust snorkeled up as it left the house or if the exhaust elbowed down. Shorkel and elbow are still in place about 24" from each other. I had cut them on the basement side, and i am now ready to reattach them, I just wanted some input before i tried to go from memory as to which was which. (I think/thought it was exhaust was down, and the intake was up). I'll call the installer and see what they/he says.
"I think it was exhaust down and intake up..."
I think you're wrong...but your best bet ( and safest) is to confer with the Heating specialist who installed your furnace .
Davo
Exhaust on a 90+ always has to be pitched up, away from the furnace, like any other flue, although in this case is's so condensate can drain back to the furnace and the condensate lines there.
Edited 9/15/2002 8:54:59 AM ET by Bob Walker
I would think that the intake is turned down so that rainwater does not enter the combustion chamber.
The exhaust pipe should be angled so that condensate will drain back to the furnace regardless of the elbow direction, but I would turn it up anyway.
Think about this: If the pipe is pitched wrong, and the elbow is turned up, the entire pipe could fill with water, whereas if the pipe was pitched wrong and the elbow was down, the pipe would probably drain out the elbow end. I don't think the elbow up direction is to facilitate condensate draining.
Edited 9/15/2002 9:42:20 AM ET by MARKH128
Each manufacturer has its own installation instructions, but as general rule you don't have to turn the end of the flue/exhaust down. Any water getting in will just drain through the system - the exhaust flue is designed to handle condenate from the flue gaes, it can handle rain water.
If you look at the flue on a condensing 90+ unit, you'll see that there are various drainage provisions on the flue.
BUT, you gotta follow the instructions for the particular unit.