2023 400 BD Shower Pan Check Valve

fwunder

Curious. A couple of times now we have filled grey tank to capacity - galley sink stops draining. In previous RVs it was always the shower drain that backed up first ( lowest ). I suppose there must be a check valve ( ball valve ) for shower pan drain?

Binghi

That certainly is our experience. Kitchen drain clog means gray tank is full. We have relied on that method probably 30-40 times. Hasn’t failed yet. I always wondered why the kitchen drain would back up before the shower drain. I bet you’re right - must be a check valve for the bathroom.

MuttonChops

Just a Question:

Do the TAB 400 have a standard P-Trap at the sink.

Believe they have a HepvO at the shower drain.

Could that be why the sink drain reacts to a full tank?

Sharon_is_SAM

I thought the 400 kitchen sink had a HepVo?

Binghi

I think it’s a HepVo. Here’s a pic of ours.

manyman297

We’ve had the shower drain overflow a few times but usually after hitching up and moving. Looking under the shower pan I don’t see any kind of check valve on our 2021 400.

Sharon_is_SAM

@fwunder - nuCamp have been adding a HepVo valve to the 400 sink drain starting with the late 2019 models.  I don’t think there is one on the shower drain - just the usual P trap with no check valve.  If you bought used, then it may be modified.

Info from a different thread: 

Denny16 Member Posts: 5,432

 March 2022 edited March 2022 75.144.241.171

Since this was originally posted, I have discovered that some. 2018/2019 TaB400s have a HEPVO valve instead of a trap on the shower drain, and some did not, but later builds of,the TaB400 have a HEVPO vlalve in the galley sink.  A HEPVO valve will not let water from the gray tank backup into the shower or sink where one is used.  The work like a one way check valve, only allowing flow from sink/shower drain to waste tank or sewer drain.  

If a shower has the HEPVO valve, the gray tank will not backup into the shower pan very easily, until pressure on both sides of,the valve are equal, then water might flow in from tank to shower or sink.  Water backing up the plumbing is going to find the path of least resistance.  If the shower has a HEPVO valve and the galley does not (as was the case in our TaB400, then water will try to back out of the sink.  If the sink and shower both have normal traps or only sink has the HEPVO, then the shower being lower path of resistance, will back up first.

Here is someone who added a HepVO to their shower along with the installed one at the sink.

https://tab-rv.vanillacommunity.com/discussion/13719/hepvo-trap-for-the-400-shower-not-for-the-faint-of-heart

qhumberd

We have a HEPVO in our sink and an trap under the shower in our 2019 (Build date Oct 2018)