Heater exhaust vs air intake: too close to work?!

[Uncle Cereal]

Got my propane system inspected today. Clogged and pierced tubing, dysfunctional pilot, etc. After a couple hours of work and a couple hundred bucks of expenses, everything's working fine! ...well, almost.

Apparently, the air intake is taking in the exhaust fumes so the heater stops working after a few minutes. "The guy" said that my exhaust pipe should stick out further than the wall (i.e. stick out from the vent) to allow exhaust fumes to leave and to allow air intake.

I told him that I understood but that the original vent was one piece and didn't allow the exhaust pipe to stick out. In a nutshell, I'm not sure he even believed me. I understand that my vent might not allow the exhaust fumes to leave as well as the original vent that had slits from one edge to the other instead of a series of three louvers. But the guy insisted that it's almost possible that it was designed like that.

My options are:
1) Connect a piece of exhaust pipe to the existing pipe and make a hole in my vent so that the exhaust pipe sticks out.
2) Sell the heater since there's apparently a market for those...
3) Just put everything back together and not use it. (Our original plan as we are not planning on using the heater this summer.)

Any thoughts?

(Am I right to assume that I shouldn't put any butyl tape and any sealant since the vent will become hot?)

3 Pictures:
-old vent,
-new vent,
-heater exhaust (round pipe in the middle) and air intake (opening around the exhaust pipe).

Thanks!
[ATTACH][ATTACH][/ATTACH][/ATTACH]

[starbrightsteve]

If the bottom picture is your new vent, then I can understand why the furnace shuts off. The new vent is extremely restrictive. If you want to use the shiny new vent, you should mount it on a spacer that holds it 1/2" away from the plane of the fiberglass and use an extension for the exhaust gas that slightly protrudes through the louvered vent. It looks like there is a diverter on the end of the exhaust pipe and the extension will fit better if you just cut of the diverter. I would use butyl to mount the vent. If you use an extension for the flue gas, the vent will be relatively cool since it is surrounded by ambient air.

[Cheech00TS]

I've been dealing with some water coming into the bottom of the furnace (where the control valve is) by way of the two tubes. I'm hoping to find a new cover for the vent that will still allow for good air flow, yet be resistant to the elements and to insects, rodents, etc. My idea was to find something like a residential dryer vent but in aluminum or stainless steel, and put a mesh cover over the opening at the bottom. This way, it would act like a rain diverter but still provide adequate ventilation. Maybe this will help.

[Casita Greg]

With that louvered cover over both the intake and exhaust I can see why your furnace is not working. As was mentioned in a previous post, that cover has to go, or be seriously modified so that both the intake and exhaust orifices are unobstructed all the way out to "fresh air".

[Casita Greg]

Duplicate post

[k corbin]

An HVAC company that does fabrication work for custom items such as plenums can sort you out very quickly. They have the tools, the skills and knowledge of exhaust and air intake requirements. Plus they will have the materials on hand. It does not have to be an RV specific business to fabricate these parts.

[Borden]

Our intake is a 4 X 2 square pipe with a 1.5 diameter round exhaust pipe in the middle of it that sicks out about 3/8 of an inch more than the intake through the intake grill. Was looking after reading this article so do not know about what is causing the problems you are having. As stated in prior post maybe extend exhaust though the louver as in our furnace exhaust; Greg has a point.

[Cheech00TS]

I haven't been able to find anything that will allow for the exhaust to extend past the shell and also prevent rain, insects, rodents from getting in through the fresh air and exhaust pipes. Does anyone have a pic of their current setup (original or otherwise) that would help the search?

[Cheech00TS]

http://www.fiberglassrv.com/forums/f...nfo-54203.html
Just came across this. May help you get someone to custom fab a new grill and vent cap, both of which seem necessary to make the furnace work properly. Hope this helps.

[k corbin]

Originally Posted by Cheech00TS

I haven't been able to find anything that will allow for the exhaust to extend past the shell and also prevent rain, insects, rodents from getting in through the fresh air and exhaust pipes. Does anyone have a pic of their current setup (original or otherwise) that would help the search?

The reason you are not finding an extension because every RV furnace instruction manual you will read says the owner should not extend the exhaust tube.

You can get screens. They have a very large mesh size so that it does not restrict the air flow. It will serve to keep out rodents and large wasp. Wasp are attracted to the propane. You should not put on a screen with a smaller size mesh opening because it is dangerous to do so.

https://www.amazon.com/JCJ-M-200-fur.../dp/B0002UHWIG

or
https://www.amazon.com/Camco-42141-F...A2K19DEF13XE7H

or
https://www.amazon.com/Camco-42150-F...X7AS8XFHW5G7YD

They don't use rain caps because it would mess up the airflow.

[Cheech00TS]

Originally Posted by k corbin

The reason you are not finding an extension because every RV furnace instruction manual you will read says the owner should not extend the exhaust tube.

You can get screens. They have a very large mesh size so that it does not restrict the air flow. It will serve to keep out rodents and large wasp. Wasp are attracted to the propane. You should not put on a screen with a smaller size mesh opening because it is dangerous to do so.

https://www.amazon.com/JCJ-M-200-fur.../dp/B0002UHWIG

or
https://www.amazon.com/Camco-42141-F...A2K19DEF13XE7H

or
https://www.amazon.com/Camco-42150-F...X7AS8XFHW5G7YD

They don't use rain caps because it would mess up the airflow.

Thanks for this.

After reading the manual referenced above, I can see what I'm looking for and now its just a matter of getting it fab'd up and finding a grill that will finish it off without restricting airflow. I may just go with a residential furnace wall vent grill and paint it with some high temp paint to keep it looking good.