[Latitude 28]

Gurus,
On out last trip we smelled exhaust fumes inside the coach when we ran the AH or the generator.  I could see smoke exiting the exhaust elbow joint at the AH.  The horizontal exhaust pipe going across the coach to the vertical exhaust pipe had a ragged fiberglass wrap that needed replacement anyway.  Investigating on how best to wrap the pipe I went ahead and removed the pipe or should I say "Sawzalled the pipe".  Once removed, the AH elbow joint was rusted at least half way around the joint hence the smoke exiting,  Also, under the wrap there were several holes rusted through the pipe.  At least from the AH I am sure this is the source of the fumes and possibly from the generator given the common connection point to the vertical exhaust pipe.  The fix is in work and will update when completed.
               

[BusNit]

That's not too bad. Put some muffler tape on it and stick it back in there! I think those pipes need to be replaced every so often from non use. Stainless steel replacement? Set it and forget it.

[Trainer]

The exhaust exits the heater through a 6 inch vertical nipple connected to an elbow connected to a 4 inch nipple. Purchase them at hardware store and replace using never seize on threads. Because installer did not use never seize, use 4 foot pipe to remove existing one from heater. These only need to be finger tight.

[Jack Houpe]

I use 308 stainless steel on most of my car projects, seems that should have been done here in the beginning. Good that you smelled that!

[Trainer]

Well Jack, it is always about the money. First, the nipples and elbow come with the new heater. That steel pipe set up is installed by the builder. So, you are wanting the manufacturer or builder to step up and spend money that will not be noticed till years and years out of warranty.

I do like your idea a lot. Where do you find that size pipe easily?

[Jack Houpe]

Yes sir Rudy I purchase it in 5-6 foot lengths on ebay I make all my exhaust systems, you can buy mandrel bends couplings all on ebay. You would be right to just replace the galvanized pieces more than likely they would out live us. 

https://www.ebay.com/itm/174536298538?ep...BMyrGimLJh

[Trainer]

Jack, I thought you were referring to the two nipples and the elbow. The steel exhaust piping lasts for a very long long time and is never a problem removing. The nipples and elbow is where the corrosion and very hard to un-screw from heater occur.

But stainless steel exhaust tubing, especially pollished like the tips one can purchase would be very nice indeed.

[Latitude 28]

Rudy,
My AH exhaust tubing was wrapped with a fiberglass blanket that in a word looked horrible!  The generator exhaust is not wrapped.  Does one have to wrap the horizontal AH exhaust tubing?

[Trainer]

Wrapping is your choice.

[Latitude 28]

That's good news....seemed like the fiberglass blanket held moisture against the pipe causing the rust on the outside of the pipe.  The generator which is unwrapped has no such rusting going on with it.