Changing Tank Vent Cap

[LewF]

I want to change the tank vents on our coach to venturi type. I need some advice on this job - the picture shows the vent cap on our rig. How do I remove this cap and when I do what will I see? As you can see this thing has a large base that is sealed all around. It looks like when I remove it there is a hole that is larger that the approximately 2 inch vent pipe. I don't think I have any problem with installing the venturi caps I have and sealing them if I am just sealing around the vent pipe. This thing looks like it is covering a larger hole. Any help is appreciated.




Lew

[Rocky Larson]

If there is a real concern that something is lurking under that dome seal you might try sealing one end of the existing "T" and attaching an elbow to the other end. Attaching the venturi to the elbow should work just as well. If not no harm done.

[Mike Canter]

Ya know that Tee vent in the picture works on the Bernoulli Effect and is a venturi. When driving down the road the air passes through the horizontal tube and creates a vacuum on the vertical pipe and draws the air out of the tank.

[justlou]

If you peal off the self leveling sealer on the base plate you will find several screws (4-6 I think). Remove the screws and the vent will lift off of the pipe coming up from the tank. The hole in the roof will be about 1/4"-3/8" larger than the vent stack. Place the new vent over the stack pipe and replace the screws. Reseal with self leveling caulking. It took me about 20 minutes to change vents.

[puttin]

Hey Rocky... that's using your noodle!

[letsgo]

Hello, I just got done with this project very easy to replace, I used a 360 siphon vent from camping world. They were 23.00 $ a pc. comes with caulk tape, Well you must first remove the old caulk use a good scraper maybe a heat gun to loosen up only if needed.Then remove the old screws, clean up area with some denatured alcohol, fill old screw holes with 5200 marine adhesive sealant about 14.00$ a tube my personal preference, if you use the 360 siphon vent it comes wth a flange that fits inside the pipe you may have to shorten the pipe cuts real easy with a hack sawthen the caulk tape goes around the pipe coming out of the roof, put a generous amount of sealant uner the flange and attach it with stainless screws and seal around the edge of the flange and cover srcews, hope this helps the 360 siphon vent comes with good directions

[LewF]

justlou and letsgo

Thanks for the information. With your information and another good look at my installation I can see the fasteners under the sealant and understand how to remove the existing cap.

justlou, what type of sealant is "self leveling", brand, etc. I would like to use something that flows and smooths out like the sealant in the picture.

Mike, I am looking to have a venturi cap that will still work when parked by rotating with the wind - if there is any. I see that the installed will work as a venturi when the coach is driving. Thanks for that information - when I looked again I see what you mean.

Thanks to all.

Lew

[LewF]

letsgo

I have looked at the 360 Siphon vent cap you installed and I think I prefer that to the Cyclone vent cap I was going to install. I am a little concerned that the Cyclone sticks up too high and that it might be knocked off by tree branches, etc. It looks like the 360 Siphon is simple and will work with air/wind from all directions. Has it worked for you. I am basically trying to eliminate odor from the commode when it is flushed. It doesn't bother me but my DW has a particularly sensitive nose and I need to solve the odor problem for her. Thanks for the help so far.

Lew

[Mike Canter]

Lew, let me know how it works out. My problem is that the drain trap in the washing machine dries out if I don't use it on a regular basis then I get gray tank odors in the bedroom. The other thing that sometimes makes it really bad if the traps dry out is if you are hooked up to the campground sewage system with the gray tank drain left open. Now sewage gases from the whole campground can come up through those dried out drain traps. I always keep the black tank closed and just drain it about every three days and I kept my gray tank open. Now I keep them both shut to prevent sewage gases from backing up.

[letsgo]

the 360 siphon vent is very low i dont have any odors at all, i hear the cyclone vent is very easy to break and does not work well in a calm wind condtion, hope this helps