Montana Vents

[elkrott]

2008 Montana 5th wheel
Two vents on top that aren't connected to pipes and I need to replace them.
What are they for and what are they called?
About 5 inches in dia with a disk inside with 5 one inch holes in it.
Connects with a threaded shaft and nut.
Part of the cover is broken off.
One at each end of the roof.

[JRTJH]

Welcome to the forum. There are four types of vents on your roof. First is the refrigerator vent, it's about 9" wide by 24" long. Second is the "roof vents" which are 14" x 14" and may or may not have a fan and a cover over them. Third are the plumbing vent's which are about 4" in diameter and finally, on some RV's (on your Montana) are "attic vents". The vent in your picture is an "attic vent". The purpose is to ventilate condensation/moisture out of the "sealed attic space" during use. There should be one on each end of your RV roof, to set up a "flow of air" through the attic space, helping to dry the air in that "dead area". Your vent, in the picture you posted has the "cover" missing. It should look like the picture I'm posting in this response.

It seems that most plastic roof attachments are "designed to fail" with UV rays, hail and age, so they are intended to be "easy to replace". Just how easy depends on how you can access the roof, how simple the job of removing old sealant around your vent stack and how much care you use not to damage the TPO/EPDM roof membrane during the job.

The vent in your picture "should be available" at most RV parts stores, but it may not be "in stock". Since it's not used on all RV's, it may need to be special ordered for you.

Here is one source for the vent: http://www.shop.classarvrepairs.com/...776-102776.htm

NOTE: The vents in your picture are, I believe, the old style. The new caps are "covered" and have a "grid work" instead of the holes. They less prone to leak during rain storms and prevent flying insects (wasps and dirt daubers) from entering.

[elkrott]

thanks for the information on my vent question.

[Williston324]

Further to these mushroom vents. I was just up on the roof doing some routine cleaning and broke the cap and base. A replacement on eBay was under $14 inc shipping and will be here Thursday. What I discovered was the original vent installation was useless. There is a 4" hole cut through the plywood and the EDPM has a three sided cut in it forming a flap that doesn't, can't move because its tight against the foil covered insulation. To reach the "attic" space the insulation needs to be cut out a bit as well. On top of this there is only one vent in the rear - no front = no air flow. They must have been in a hurry that day at the factory!!

[Clays390]

Just a quick note: to slow the UV breakdown of the plastic give it a coat of plastic compatible paint with UV protection prior to install. Makes them last longer.

[PARAPTOR]

Yes the UV does a job on these caps, had to replace both of mine. Can not find pictures?? Lets just say what was left was as brittle as potato chips Have not done it but was thinking of spraying the caps with that advertised rubber spray "flex seal" Comments??? When I find pictures, if ever, I will post. $14 sounds like a good deal. replaced my two about two years ago was $17 including shipping and still had holes rather than grid. Since my caps were only damaged just spun new caps on existing original base, did not want to disturb original seal if I did not have to

UPDATE: picture added, John you were right replacement units have a screened type base, guess was thinking about the original one that I decided not to remove

[Clays390]

Krylon makes a clear for plastic that has the UV protectant, http://www.krylon.com/products/fusio...plastic-clear/