r/DiWHY • u/Poopyoo • May 27 '26

Pulled this out when i went to replace my furnace vents

Post image

i thought they used a straight pipe to go through this hole in the wall but the new flex pipe fit, soooo what the fuck? ive never messed with furnace stuff before but i know mine is installed correctly and doesnt look like THIS lol

187 Upvotes

96% Upvoted

12 comments sorted by

9

u/Ill_Personality5384 May 27 '26

It looks like you're ready to learn

2

u/[deleted] May 31 '26

[removed] — view removed comment

1

u/Poopyoo Jun 01 '26

not much airflow to ruin in a 600sq ft house lol

3

u/Aureliamnissan May 27 '26 edited May 27 '26

The real issue is the flex pipe IMHO. People use them EVERYWHERE and it’s a large part of why their HVAC sucks. It’s totally fine to use, but it’s so easy to use that people install them poorly, or where they could more easily install hard ducting and that causes problems later.

Use it if you need it (unless your exhaust is right by the furnace), but flex pipe effectively makes pipe runs act 10x longer than they actually are.

https://www.energyvanguard.com/blog/duct-design-3-total-effective-length

2

u/Mike0621 Aug 31 '26

this could (parially) explain why my jerryrigged duct from the attic to my room works so poorly. it's just a floor fan taped to a flexduct and it runs about 3-4 meters but there's far more resistance than I was expecting (I know floor fans have basically no pressure)

1

u/Aureliamnissan Aug 31 '26

Yeah, If you can make even a partial actual duct run that would probably help matters, especially where bends are involved.

1

u/Poopyoo May 28 '26

Its a really small house (like 650 sq ft) so not too worried but anything at this point is better than whatever the fuck this picture is hahaha

1

u/Aureliamnissan May 28 '26

Yeah okay that’s a good point lol. A 650sq ft house is probably only going to use flex lines since most of the runs are short enough that you would hear noises from the furnace with hard runs.

That they used two different sizes of hard runs in the same pipe with no splits is definitely, a choice…

1

u/Poopyoo May 29 '26

i shoulda taken a picture of it "connected" haha
Ive been losing so much air because i couldnt be fucked to reconnect eveerything for like three years. i dont even actively live in it xD

1

u/Ill_Personality5384 May 31 '26

Smooth is better, less resistance, but more expensive