Chimney within a chimney

Jon mackay · 05-08-2007, 09:52 AM

I came across this installation today where a metal chimney was covered by one of those fake metal brick looking encloseres. It seemed to me that there could be draft issues but I thought I would check.
Any information would be appreciated.

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**neal lewis** · 05-08-2007, 01:13 PM

Jon,

The installation was designed that way, so I would doubt that there would be a draft issue.

I would be moew concerned about clearances with the with metal flue, most likely a b vent. I find that when those were installed years ago, no one seemed to care about proper clearances to framing, etc.

Jon mackay · 05-08-2007, 01:20 PM

OK, thank you Neal.
You are correct, bad clearance in the attic.

I noticed a lot of soot coming out of the front of the unit also. I am not real familiar with this type of installation for mobile homes but it just looks a bit scarfey to me..

**DavidR** · 05-08-2007, 06:54 PM

Did you happen to check the draft on it Jon?

Jon mackay · 05-09-2007, 05:14 AM

I was unable to check for draft because it was all enclosed. I did not detect any CO in the area while running but due to the warm weather, it did not run for long.

**Bob Harper** · 05-09-2007, 05:29 AM

We need a lot more info. here. You need to identify your system here because that will guide you to your answers.

The furnace appears to be an oil unit with a gas conversion burner. That flex connector is too long and not approved to penetrate cabinets, btw. Any rating plate or firing data? These oil furnaces used an 1,800F triple walled listed chimney. What I'm seeing here appears to be single walled pipe stuffed in at an angle into a different single walled pipe or possibly B-vent. It also appears they ran 6" into a crimped down 7". You cannot mix B-vent with factory chimney, btw. It also would need elbows and supports for that offset.

The factory chimney had its own termination plate and this ain't it. This appears to be some bastardized single walled pipe stuffed into a factory chimney housing. This makes the housing a "shroud", which is illegal and most be removed.

I recommend this entire abortion be replaced with the appropriate chimney or vent. For oil, you would need a UL103 factory chimney or L vent. For gas, only if this unit was approved for it, could you use properly sized and installed B-vent.

Just curious, where would you have tested for draft and CO and how?

Jon mackay · 05-09-2007, 08:38 AM

Very good information, thank you.

I have attached the information plate picture along with all other views of the unit.
Thank you again for your input.

I checked for CO at the register although there was not much air flow. As far as draft, I was not able to check for that.

I also could not see any duct work at all so who knows what that looks like.

Jon mackay · 05-09-2007, 08:39 AM

And here is the info plate, I had to downsize the photo a bit.

**Jim Luttrall** · 05-09-2007, 09:37 AM

Did everyone note it is a mobile home listed furnace? Safety is safety, but there seems to be a very different meaning of "safety" when talking about tornado bait, er, I mean mobile homes and the associated codes.