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Old 06-30-2016, 01:20 PM   #1
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1974 25' Tradewind
Lexington , Kentucky
Join Date: Nov 2015
Posts: 15
Hepvo valves are new to me

We have the frame and floor redone......drifting towards ordering/working on the black and gray tanks.
Since we are getting new tanks, fittings, shower, toilet and sink.........thought about just letting the shower drain directly into the gray tank and not using a "P" trap on the shower! This lets the shower water go in the top of the tank, no p trap pipe entering from the side = more available tank volume.
Question 1: If I plug the shower hole with a stopper, will that be enough to stop the gray water smell into the camper (would also keep "odor" tablets in the tank).
Question 2: According to Hepvo p trap or vent to the outside needed .......has anyone verified this on their re-do?
Thanks for the help.

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Old 06-30-2016, 01:31 PM   #2
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1991 34' Excella
1963 26' Overlander
Central , Mississippi
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I've used hepvo valves on a couple of refits. The only thing I dislike is finding fittings to adapt them into plumbing. Oh, the price is kinda tough also.

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Old 06-30-2016, 01:35 PM   #3
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1991 34' Excella
Princeton , New Jersey
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Let me just say this. The smell coming from an older gray water tank smells far worst than the black water. And you will forget the plug at least once.

The vertical clearance under the shower may be a limiting factor unless you can stub the valve directly to the top of the tank. Tricky alignment issue.

Under a sink maybe yes because you could get to it if there was a problem.
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Old 06-30-2016, 01:44 PM   #4
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1955 22' Flying Cloud
1964 17' Bambi II
Clear Lake Shores , Texas
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1. I think you will want a Hepvo or P-trap. Open drain is a bad idea.
2. I have had mixed results with Hepvo's. I bought three for my tank project and the two vertically mounted ones work great. The one I mounted horizontally (for shower drain) failed to work and I had to use a p trap instead.
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Old 06-30-2016, 04:32 PM   #5
in the rising sun toaster
1956 26' Cruiser/Overlander
Wimberley , Texas
Join Date: Apr 2015
Posts: 52
Have you considered allowing the grey tank to be filled via its bottom "outlet" fitting? My AS didn't have a grey tank originally, so when I added one, ~30 years ago, I wanted a P-Trap so chose to have the tank fill from the tank's lowest point, its outlet valve, just like some airplane wing fuel tanks fill. My shower pan has its drain right at floor level and the P-Trap is plumbed in under that drain, and then to a "T" w/ one side proceeding to the grey tank's "outlet" thus filling that tank. The galley and lav sink drains enter this pipe via "T's". Downstream is the slide valve that's mounted in a commonly seen combo dump connector plumbing fitting that's designed to take 2 slide valves, with left side valve for grey tank dumping and right side slide valve for black tank dumping and center is the main outlet to slinky. A top-side-of-grey-tank "port" is there too for the required connection to the vent stack that goes up to the roof. Of course, constructed w/ just-right gradients so full draining properly occurs at dump time. 30+ years later, and w/ the required PM work on the slides' gaskets, this setup still allows 2 sinks and the shower to drain just fine, as fast as any top-fill draining tank system, and no odors.
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Old 07-01-2016, 09:22 PM   #6
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1962 19' Globetrotter
New River , Arizona
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Posts: 65
I used one Hepvo valve horizontally, between my sink - shower drain pipes, putting it just in front of the inlet for the Grey tank, under the floor. Fittings were tricky to manage. But, have eliminated J/P traps and vent stacks for each with no smell or drainage problems in 4 summers of traveling in our '62, 19' Globetrotter.
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Old 07-02-2016, 02:28 AM   #7
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Metairie , Louisiana
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My 2012 Airstream Interstate came equipped from Jackson Center with Hepvo valves on the shower (more-or-less horizontal) and both sinks. There are several advantages to Hepvo valves, not the least of which is that you don't have to fill them with antifreeze when winterizing— in fact you can't fill them!

And there is another quirk that may or may not be a benefit depending on how you look at it. A Hepvo valve is a type of check valve, and unlike a P-trap will not allow water to flow backwards. That means that if you overflow your gray tank from the galley sink, the only drain that backs up is the galley sink. Your shower will not back up just because it's lower than the other drains.
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Old 07-02-2016, 05:38 AM   #8
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1964 17' Bambi II
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Schererville , Indiana
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We used the Hepvo valves on our Bambi II rebuild for the shower & sink in the galley. In such a small space, the galley one worked out great. Gave us a lot more space under the sink for storage. No problems in 4 years. And yes, grey water does smell bad!

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1988 Avion 32S
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Old 07-02-2016, 05:55 AM   #9
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Old 07-04-2016, 07:18 PM   #10
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1988 32' Excella
Robbinsville , New Jersey
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I can't see how a stopper is going to keep all the odor out of your trailer if you're going to use the shower and have it drain directly into the gray tank.

You would need to take it out to drain the shower and let the smell in or not have a drain at all and bail the water into the sink.
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Old 07-04-2016, 07:50 PM   #11
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Cerritos , California
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I have one under the sink and one under the shower. Both are working as advertised.

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