Tank sanitation leak

chevyman30 · 04-25-2022, 07:08 PM

Good evening all,

An issue that I have, and have been told by the dealer is a chronic failure of a check valve got is in line when you sterilize the tank.

This causes a leak under my bathroom vanity. Of course I will have to replace several boards of the vanity. I should have paid attention to the beginning of the boards being wet. Lesson learned the hard. Now for the Dilemma.

I cannot locate the exact location of this apparent valve has failed when I use the tank sanitizer on my 2015 Jayco greyhawk 31 f k.

I've seen a couple of pretty good YouTube videos in addressing the issue but none of which shows the exact fix or location.

Any and all help will be greatly appreciated.

dxrobertson · 04-25-2022, 07:27 PM

In reference to your "tank sanitizer"; do you meant the black tank rinse where you connect a hose to the fitting on the outside of the RV and rise the black tank?

If so, yes this has a check valve/vacuum break. These can leak. They are usually located in the general area of the outside tank rinse hose connection. Thus look inside "behind" about where the external hose connection is. Whatever is "there", you will have to remove to gain access to the flush plumbing (backside of cabinet, storage wall... whatever).

Where you have water damage from the leak "under the bath sink" would be a good place to start; is that area about where the external hose connection is?

chevyman30 · 04-25-2022, 07:53 PM

Thank you for the quick responsen

Yes it is a 'tank rinse'. When I use the tank rinse, it leaks. It starts from behind the toilet and from there it goes to underneath the bathroom vanity sink area. It sucks having to get behind the with the area as we have to crawl in there can unscrew a dozen screws from the panel. Poor design but of course modified following years.

I will start from exactly what you said, and get behind wet bay.

As far as the water damage I think I'm just going to have to custom make the boards and try to match the paint.

Thanks again and wish me luck.

pconroy · 04-25-2022, 08:11 PM

I have a 2016 31FK and I'm trying to visualize what you're saying. Let me think about it, but if you need me to look at something in mine, to compare, I'm happy to do so.

pconroy · 04-25-2022, 08:16 PM

Let's make sure I understand - you say "sterilize" but you mean the Black Tank Flush, right?

When you hook a hose to the black-tank flush and turn on the water - the water leaks from where? That's where I'm confused.

I don't know - and I can try to look up and under mine, but I had GUESSED that the tubing from the black-tank-inlet just went down from the water valves and under the coach to connect to the nozzles in the black tank.

Thus - my GUESS would have been that any leak in there would have dribbled onto the pavement and not gotten the vanity wet.

My 31FK is out front for a couple of days - let me know what I can do to help you locate the leak.

chevyman30 · 04-25-2022, 08:43 PM

I think my number one question would be if you know where the check valve would be located. Since while using the wrench I noticed water coming from the area of the toilet on the outside.

From what I can remember I believe the compartment behind the wet thing is water tight. I will go out there tomorrow and check to see if that apartment has the check valve. I always felt that it was a poor design because that is where the water filter is and I've not used to because of them manner in which you have to crawl in there and unscrew a dozen screws just to get access to behind a panel.

Attached are photos where I found the water damage inside.

And now I have to put my carpenter skills to the test

dxrobertson · 04-26-2022, 04:28 AM

Quote:

Originally Posted by chevyman30

I think my number one question would be if you know where the check valve would be located.

Usually the black tank rinse check valve/vacuum break is located just inside of where the tank rinse hose connection is. there should be an elbow at/near the inside of the hose connection, a short pipe run up, the valve, then a run of pipe back down. These are mounted at a high point between the hose connection and the rinser at the tank.

I had a leak from inside my bath cabinet. I was able to carefully remove the cabinet floor to gain access to the void under it. There I found all the plumbing runs. Maybe from there you could follow the leak back to its source. To remove the floor, I recall I had to 1st remove the inside cabinet walls (the floor slid under them).

Scoutmaster253 · 04-26-2022, 04:57 AM

Quote:

Originally Posted by chevyman30

I think my number one question would be if you know where the check valve would be located. Since while using the wrench I noticed water coming from the area of the toilet on the outside. ...

In my 2014 31FS, this valve is mounted under the sink in the bathroom. It is high, nearly touching the underside of the countertop.

When I discovered that mine leaked, I removed it and found that there is a small ball inside it that makes the seal to allow this valve to vent while also allowing the flushing water to get into the black tank. On mine, this ball had gotten out of its sealing area, so any water I tried to use to flush the tank actually went onto the floor under the bath sink. I think that the flush station water pressure was higher than the 125psi max this valve was designed for.

We need to be careful about the pressure at which these flush station supply hoses operate.

chevyman30 · 04-26-2022, 07:54 AM

Thanks for the quick replies.

Since I'm stationary for the next couple of months I'll wait another week or so before taking on this task of prying away the damage boards and reconstructing them. And of course with the weather getting a little warm and durable in the Northeast, I'll take all the trash from underneath my storage and get to the area behind the with the and start from there.

It's all about moving forward with progress and I like to thank everyone here. I'll chalk it up as lesson learned and I should have paid attention to the signs of water damage.

Happy trails to all and I will be forwarding any pictures that could be of some use to anyone.

Parrott · 04-26-2022, 10:39 AM

This has been discussed on her before. Some have replaced this valve with a shark bite back flow valve. You should find it’s mounted up high most likely in the cabinet

chevyman30 · 04-26-2022, 12:01 PM

Thank you all, as promised here are the pictures from behind my wet bay. A real pain in getting to it, but what isn't a pain when dealing anything.

Now to get into the cabinet/vanity.

Wish me luck.

PS sorry that the pictures are on its side just note that if you twist it to the right then that's what they are.

LuckyDuck · 04-26-2022, 01:52 PM

Quote:

Originally Posted by Scoutmaster253

… think that the flush station water pressure was higher than the 125psi max this valve was designed for.

We need to be careful about the pressure at which these flush station supply hoses operate.

Out of an abundance of caution, I put a cheap pressure regulator between my back flush hose and the hose bib it’s attached to. I may not get quite as strong of pressure in the tank, but I worry less about blowing out the cheap backflow fitting.

pconroy · 04-26-2022, 05:01 PM

That's exactly what the back of my wetbay looks like too. Good to know they didn't change much in a year.

Yeah, I was confused too. The only check valve I had heard of is the one right at the inlet. Where the hose connects. I had no idea there's another one behind the vanity.

I hope you can see it if you pull the drawers out maybe???