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mikebough · 08-03-2014, 09:58 AM

Rvers and Future Rvers
If you have or plan to purchase an RV please be sure to check the plumbing, especially the way the black water tank is vented and whether a sink or something else is connected to the vent.
I have worked in construction for over 40 yrs. And have always had an rv because of so much time on the road. I have owned a Newmar, a Fleetwood, a Jayco, A Beaver, A Coachman and now a Keystone. Each one of these had the tank vented to the atmosphere out the roof except the Keystone Cambridge.
We have had this fifthwheel for about a year and from the start noticed that something was wrong with the blackwater tank. We were getting a sewer smell in the unit, we were having to dump the tank twice a week and some of the time when the tank was about ¾ full and you flushed the commode there was air pressure from the tank that would blow the water and whatever else was in the commode out and over the bathroom walls. I thought the vent may be blocked so I got on the roof and ran a hose in both vents for about 10 min. but both were clear.
Last week I was flushing the black tank the same as I and many other rvers do by filling the tank ¾ full and then dumping it. While I was doing this a friend came by and I didn’t pay attention to what I was doing and I overfilled the tank. I have seen this happen a dozen times to other people and the waste water would always come out on the roof but with the way Keystone plumbed this unit the water came out the bedroom sink . It flooded the entire unit with dissolved tissue paper and crappy smelly water.
Instead of running the drain from the sink over to the shower drain they ran it to what should have been the blackwater tank vent and added a pro vent to the drain line under the sink cabinet. The pro vent is nothing more than a check valve that lets air into the drain but won’t let air out thus the pressuring of the black tank and rendering it without a vent. What was happening was the tank would pressurize because of the heat and chemical reactions and force gas back through the P trap for the bedroom sink and smell up the unit or if we flushed the commode it would spray everything in it out onto the floor and walls.
I don’t know if this was done like this as a cost savings or what. I contacted Keystone and they said that the previous owner must have changed the plumbing because they would not have done it like this. I have since went online and found the same exact unit in Alabama and Tennessee at Camping World. I had the salesman E-mail the pictures of the plumbing and they were identical to mine. I find it hard to believe that three different people from three different states would make the same stupid change. So check everything carefully when buying because it’s a big investment and not all companies will admit to a screw up.
I have cleaned the unit and carpet as good as possible but we are staying with my wife’s mother until all the smell is gone which may be a while as the carpet pad was soaked and the crappy water seeped under the bed, the shower, all of the cabinets , the fridge, and all of the slides.
Be careful
Mike B

bamaboy473 · 08-03-2014, 10:07 AM

Hate to add bad news to what is already a lot of it for you, but can you file a claim with your insurance company? I imagine that it's a total loss unless you remove all carpet and pad and under all cabinets.

The kibbles 'n bits that are in sewer water will morph into mold and dry rot within the closed spaces and luan sheets. There is no way to correct sewage that's hit carpet pad. Sorry to hear of the event.

Fred1609 · 08-03-2014, 01:39 PM

Definitely call your insurer...What a crazy plumbing set-up

mikebough · 08-03-2014, 05:21 PM

Quote:

Originally Posted by Fred1609

Definitely call your insurer...What a crazy plumbing set-up

Some dumb ass engineer thought that because it is called a pro vent that it must be good. A pro vent is actually an air admittance valve that lets air into the line but won't allow gasses out.
Mike b

Dog Folks · 08-03-2014, 07:56 PM

We have a pro vent just like you describe in our Keystone Outback, except, I know for a fact that the tank also has a stack vent going through the roof.

We only have two vents on our roof. They are side by side. One is for grey water holding tank, and the other is for black water.

mwwade · 08-03-2014, 09:17 PM

Sorry to hear about your problem, and I thought I had problems! Why was I not surprised to hear the reply from the rv company.

paz · 08-04-2014, 05:11 AM

Quote:

Originally Posted by Dog Folks

We have a pro vent just like you describe in our Keystone Outback, except, I know for a fact that the tank also has a stack vent going through the roof.

We only have two vents on our roof. They are side by side. One is for grey water holding tank, and the other is for black water.

Ditto on the roof vents, and each drain also has an air vent under the sink. The air vents are designed to allow air in, but not to allow gasses out. They should also prevent water from flowing out.

mojoracing · 08-06-2014, 05:45 AM

I had a similar issue on a gulf stream independence super c. Couldn't figure out why the black tank was filling up so quickly. Discovered the bathroom sink drained into the black tank. Always had an odor in that coach and Im assuming it was due to the p trap draining when bouncing down the road.

MtCamper · 08-06-2014, 04:50 PM

Believe it or not that was probably by design. Lots of RV manufacturers have had black tank complaints related to not using enough water when you flush. Many, if not most, now plumb the bathroom sink into the black tank. some do the shower as well, but that's not too common. Easy to figure, hookup your drain and use one fixture at a time and see what tank floes from. Never heard of anyone filling the black tank to the point it comes out the roof. Sounds as if that was a negligent act on your part and don't think your insurance should be responsible. We all pay tuition at the school of hard knocks.

mojoracing · 08-07-2014, 12:45 AM

I did it just last week. Not that big a deal if it comes out the roof vent but he's saying the factory didn't vent the tank out the roof and just used a pro vent so it came out the sink. Negligent? Maybe, but if it was plumbed like 99% of rv's it would have ejected outside the unit and not into it. If he was just flushing it, I would think the water wouldn't be that bad. I was lucky and had already dumped and flushed the tank once already so the water coming off the roof was clear.

chertz · 08-07-2014, 05:35 AM

I am confused here. .. If in fact the bathroom sink is plumbed to the black tank, and assume there is a vent out the roof... how again would an overflow come out the vent pipe before the sink 4-5 feet lower than the vent?

Also, assuming the OP was filling the black tank with a hose thru the toilet, vent or not the tank would have overflowed out the toilet with the valve held open by the hose, as it would be the lowest point.

In his situation a vent wouldn't save his unit from flooding unless the black tank was vented with no p trap appliances inside the unit and the toilet valve not held open by the hose.

mojoracing · 08-07-2014, 11:05 PM

I was assuming he was flushing via a sani flush and the rig either didn't have a roof vent or whatever type of back flow valve or lack there of failed on the sink drain.

Tony Lee · 08-08-2014, 12:22 AM

Quote:

I am confused here. .. If in fact the bathroom sink is plumbed to the black tank, and assume there is a vent out the roof... how again would an overflow come out the vent pipe before the sink 4-5 feet lower than the vent?

Exactly - and the same would happen on any rig with a basin draining into the black tank. Those who get water coming out of the roof vent either don't have other fittings running into the black tank, or have a check valve between the basin and the black tank.

Burping when flushing the toilet once the black tank is partly full is often due to the roof vent pipe extending too far into the tank

rivraton · 08-09-2014, 12:59 AM

Quote:

Those who get water coming out of the roof vent either don't have other fittings running into the black tank, or have a check valve between the basin and the black tank.

Even if this were the case, the vent cap is not sealed to the stack, it's only function is to keep out rain /debris, so if you could force the tank contents up and out of the vent stack, a good portion of it would end up in the wall cavity that the stack travels through!