Plumbing problem.

LandKO · 04-17-2021, 01:22 AM

This afternoon, after flushing toilet (#2), draining of the toilet became sluggish and gurgling was heard coming out of the bathroom sink. Now there is standing water in the sink. The toilet still flushes but very slowly.
I thought the sinks used the grey tank while of course, the toilet, the black tank.
I also thought there is no connection between the two tanks other than the drain valves.
Does anyone have a suggestion as to what is going on?
Thanks

Bob Denman · 04-17-2021, 01:29 AM

Bathroom sinks drain into the black tank.
The question is: why are things moving so slowly?
Have you drained the black tank?

**16ACE27** · 04-17-2021, 01:31 AM

Your black tank is full. A short search of this forum would yield dozens of results telling you the bathroom sink is plumbed to the black tank in most Thor coaches. You can go to the Thor Owners Resource website and create an account with your VIN and download all kinds of resources for your coach including a plumbing diagram.

LandKO · 04-17-2021, 01:36 AM

Thanks for the replies. I’ll go and dump the black tank in the morning.
We’ve only been out 4 days. Have never had a black tank fill up so fast.

Bob Denman · 04-17-2021, 01:41 AM

At least the solution is pretty easy...

LandKO · 04-17-2021, 01:42 AM

We will see.
I’ll let you know.

**16ACE27** · 04-17-2021, 01:47 AM

Quote:

Originally Posted by LandKO

Thanks for the replies. I’ll go and dump the black tank in the morning.
We’ve only been out 4 days. Have never had a black tank fill up so fast.

A lot of factors to consider:
How full was it to start?
How much of the 26 gallon tank is usable?
Probably not real careful of bathroom sink water use if you think it's going to the grey tank.

I'm sure you'll find the solution tomorrow.

Bob Denman · 04-17-2021, 01:49 AM

. Let 'er rip!

Trophy1200 · 04-17-2021, 02:14 AM

Quote:

Originally Posted by Bob Denman

. Let 'er rip!

That's what caused the problem in the first place.....

standerson · 04-17-2021, 02:19 AM

Quote:

Originally Posted by Trophy1200

That's what caused the problem in the first place.....

LandKO · 04-17-2021, 04:22 PM

Quote:

Originally Posted by 16ACE27

A lot of factors to consider:
How full was it to start?
How much of the 26 gallon tank is usable?
Probably not real careful of bathroom sink water use if you think it's going to the grey tank.

I'm sure you'll find the solution tomorrow.

This was our first outing of the season. I emptied and flushed all (black, grey, fresh water) tanks at the end of last season, so the black tank should have been empty when we started out.
In the three years we’ve had this RV, this is the first time we’ve had an issue with the black tank being full, and we typically can spend 6 or 7 days out without having to dump.
My only guess is that somehow the bathroom sink was left running, however slightly, which contributed to the tank filling prematurely.
We are at a COE campground so there are only the park dump stations. So, this morning we disconnected water and electricity, pulled in the slides and we went and dumped.
Problem solved at least for now.
Thanks all.

Danny boy · 05-01-2021, 07:14 PM

Quote:

Originally Posted by 16ACE27

Your black tank is full. A short search of this forum would yield dozens of results telling you the bathroom sink is plumbed to the black tank in most Thor coaches. You can go to the Thor Owners Resource website and create an account with your VIN and download all kinds of resources for your coach including a plumbing diagram.

Where on the Thor site are the plumbing diagrams? I could not find any reference to them.

Thanks,
Dan

atreis · 05-01-2021, 07:31 PM

You can get all of the manuals and diagrams for your specific coach here:
https://www.thormotorcoach.com/owner-resource/

If you haven't registered, you'll need your VIN.

Danny boy · 05-01-2021, 10:23 PM

Thanks, Atreis!

LandKO · 05-01-2021, 11:09 PM

The plumbing diagram for Thor class C and A motorhomes is generic. The actual diagram shows the lavatory sink plumbed into the gray tank. However, there is a note at the upper r/h part of the page that caveats that “some” units have the lavatory plumbed to the black tank.

atreis · 05-02-2021, 12:28 AM

Mine is specific to my model, but not my unit. (There are a couple schematic variations for rentals vs. non-rentals for my model.) The sewage diagram clearly shows the bathroom sink going to the black tank in my unit. I added the red arrows and text.

Wandering Woods · 05-02-2021, 04:03 AM

My diagram is specific to year and model (2018 Axis 25.3). I was surprised to see the sink plumbed to the black tank especially when the kitchen grey pipe runs directly by the sink.

We used to dump wash waster in the toilet. No more and we even brush our teeth at the kitchen sink.

Pete'sMH · 05-02-2021, 05:02 PM

Quote:

Originally Posted by Wandering Woods

My diagram is specific to year and model (2018 Axis 25.3). I was surprised to see the sink plumbed to the black tank especially when the kitchen grey pipe runs directly by the sink.

We used to dump wash waster in the toilet. No more and we even brush our teeth at the kitchen sink.

They put the bathroom sink water into the black tank on purpose. It helps the black tank to empty more easily if it has more water than most people use when they flush. And also, for most people the grey tank fills faster than the black so it helps even it out. And, you should know that Thor’s drawings are proprietary and protected. You run a risk of getting censored by the moderator.

Wandering Woods · 05-02-2021, 07:41 PM

I don't know why proprietary would be an issue since they don't always follow them. Thor didn't build my waste lines like the diagram. At first I posted another thread about the dumb design for the 2nd black tank valve, but then I found the schematics and found the design was OK. Someone just decided to put the valve in a less accessible location. 1st quote to fix is $900. Ugh.

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