Why can't you mix single wall and double wall pipe?

[CTburning]

I have always accepted the rule that you can't mix single wall and double wall pipe. I am not trying to argue but why the universal rule? I am rethinking my basement installation and slightly stretched the limits to combustibles on the ceiling. I have come up with a simple and inexpensive solution of using two 45's instead of a 90 to surpass the inch or so that I need. One of my options was to use double wall and that got me thinking.

 

[vvvv]

only you or i can! shhhhh...

 

[polaris]

No worries. Just the fact that your thinking/asking about it shows your logically thinking it through as opposed to your average Joe. I assume it's the price difference that's got you thinking about your choices.
Joe

 

[begreen]

They often don't mate well, but the primary reason would be clearances with a secondary reason of keeping the flue gases from cooling down. What is the specific clearance issue and why not do it with double-wall 45's?

(Caveat, Pook uses a MagicHeat to accomplish this heat loss.)

 

[vvvv]

They often don't mate well, but the primary reason would be clearances with a secondary reason of keeping the flue gases from cooling down. What is the specific clearance issue and why not do it with double-wall 45's?

(Pook uses a MagicHeat to accomplish this heat loss.)

if clearances are met, i see no reason why u cant mix & match however St. Picasso might want it.

 

[Pagey]

Can that cat flush?

 

[Wood Heat Stoves]

safely or logically it is possible, but the pipe makers have never tested for mix match like that, so you wont have ul listed stack, and it wont be "to code"

 

[vvvv]

Can that cat flush?

that 20 yr old prick refuses or forgot how to chit in the sawdust pile in cellar. never laid on tank be4 + other strange actions lately. he does still sit upon request

 

[Pagey]

Can that cat flush?

that 20 yr old prick refuses or forgot how to chit in the sawdust pile in cellar. never laid on tank be4 + other strange actions lately. he does still sit upon request

Sounds like he's a candidate for prescription meds.

 

[tiber]

I'll speak for duravent here, which is what I'm familiar with. Double wall has "vents" (little circles) which I suppose are to be vented to the outside. If you're mix and matching, those are probably filling up with deposits, aside of the fact that the double wall is making hot spots in the system where the single wall is present. I think I'd just keep an eye on it to make sure it's not filling up the airspace in the double wall with creosote or whatever.