Oil Furnace with flexible exhaust to concentric wall vent

Looking for some advice. I am seeing 2 things I have not yet seen with an oil burning furnace. Flexible tubing leading to a wall concentric vent. I’m in Quebec and haven’t seen any concentric vents and certainly no flexible tubing. I am recommending a certified technician verify the set up but am lacking some knowledge as to the code. Any advice?






I have seen this setup here in Ontario and it is just fine.

It’s a good thing to suggest having it checked by a qualified contractor if you are not sure.


I Agree however I have found them leaking at the seams. They are not a really good design. The sealant on the connections must be able to handle the heat and they fail all the time.

I disagree with the assessment that everything is fine.

  1. Unless you know manufacutures specs you don’t know its correct.
  2. The reduction form 6" to 5" to 6" is odd. Most always if a reduction then it should be uniform through out.
  3. Is this high efficiency ? Is so the venting should have a double walled intake - fresh air and exhaust in two different tubes.
    I as with original poster suggest further evaluation by licenced technician prior to close of title.

Maybe I should have been a bit more clear in my response.

I have seen this setup in a small community north of where I live.

I have inspected two homes there and both are setup like Jarrett’s picks.

Like him, I was unsure, so I checked with a local HVAC contractor at the time and he stated it was fine. The client checked with an HVAC contractor and the client let me know that his HVAC contractor agreed with the one I spoke with.

I just offered an opinion based upon my previous experience
Sorry Raymond


is there a power vent on this unit?

What type of burner? ** Beckett or Riello

The mere fact that high temp silicone is smeared all over the reducer is indication enough for me this set up is questionable.

The third picture does not look like a manufactured certified thimble, more of a made in field.

If its a true concentric set up there would be a secondary incoming combustion air line.

On the exterior picture the gas line is in very close proximity of the exhaust.

And without further info on the type and make of furnace along with age or whether its a complete replacement of upgrade those would be my concerns fwiw.


Echoing Mr. Wand’s post, if it’s concentric, how is this design supposed to work?

Thanks all…will be getting a further opinion from an expert on this one. Will repost with further information when available.

Late Followup to this original post. I did have a furnace specialist check this out. According to them, everything was up to code. The side vent, silicone and flexible tubing met the norms and that it was a ‘‘more recent’’ type of set up. Personally, I find it cheap. We are talking a + 1 million dollar home here. I strongly suggested a carbon monoxide detector and that personally I wouldn’t be very comfortable with this set up in my own home. Didn’t phase the buyer at all. Well…I did what I needed to…a good CYA clause and the rest is up the them! Thanks all for your responses!

I have nailed 2 HVAC installers for saying the same thing and doing an air sample to prove there stupidity of this set up. Both were shocked to see what can happen with this design.
One of the HVAC contractors was so shocked that his set up could be detected from the bedroom upstairs. If anyone says this is OK, it does not mean it is OK! until a proper test is done.
Make sure you recommend a kidde gas detector and CO.