Thetford Macerating Toilet

boowho · 08-03-2015, 08:34 PM

This is probably a venting problem, but as my black tank nears full, the toilet will not retain any water after a flush. Water that is supposed to stay in the bowl after flush get's sucked out, leaving the bowl dry.

Empty black tank, everything is fine again.

This is only on this particular toilet. Have standard marine type head in the half bath, never exhibits the symptom.

Any plumbers out there? Anyone else had this issue? Maybe I should regard as a "feature" since I always know when the black tank is nearly full.

Boowho??

15berkxl · 08-03-2015, 09:18 PM

Is the control panel toilet symbol red or yellow when it acts up?

Wayne

boowho · 08-03-2015, 09:25 PM

Quote:

Originally Posted by 15berkxl

Is the control panel toilet symbol red or yellow when it acts up?

Wayne

No.... Always Green.....

Boowho??

15berkxl · 08-03-2015, 09:39 PM

That's strange mine turns yellow when tank gets almost full and then turns red when full. Of course it won't flush when red.

Wayne

dan-nickie · 08-03-2015, 09:55 PM

I believe it is a feature. My rear bath toilet acts similar, but I haven't paid much attention to the lights.

What is strange on mine is that it seems to be wired to the grey tank. When the grey tank gets full my rear toilet won't flush. Strange huh?

15berkxl · 08-04-2015, 06:23 AM

Upon delivery I discovered that FR installed the dump valves backwards so the black had a gray handle and gray had a black handle.
If they did that they could easily wired things wrong.

Wayne

Gottawonder · 08-04-2015, 08:18 AM

Dan I have reached the conclusion that mine is wired to grey tank as well.

dan-nickie · 08-04-2015, 08:33 AM

Quote:

Originally Posted by Gottawonder

Dan I have reached the conclusion that mine is wired to grey tank as well.

Must be a thing with the 2014 390RB model..

Neanderthal · 08-04-2015, 10:03 AM

Mine was wired wrong as well and always showed yellow. Had the dealer fix and ended up with sensors on grey and black took another repair shop and they corrected the problem and found the root cause was the sensors had been placed on the tank behind a metal brace a phone call to Thetford revealed that this would cause interference with the sensors causing false readings after modifying the bracket to allow clearance for the sensor all is good.
Also, by design the water will not fill if sensor starts reading full and will stop flushing this is per owners manual.

boowho · 08-04-2015, 10:43 AM

Quote:

Originally Posted by 15berkxl

That's strange mine turns yellow when tank gets almost full and then turns red when full. Of course it won't flush when red.

Wayne

Mine used to do that..... That feature of the toilet was disabled when my SeeLevel gauges were installed. I don't believe that would have any bearing on my problem.

Boowho??

Phil57 · 08-04-2015, 03:52 PM

Boo if I understand correctly the issue is the water drains out of the bowl. It has nothing to do with tank levels. Correct? If so mine does the same and. I have had the board replaced twice and FR replaced the toilet and still the same. No matter what I do the water will not stay in the bowl but to confuse the issue it works correctly sometimes. Nothing but fun.
The fix according to Thetford is to use a wire tie to hold the discharge hose up higher. I haven't done this fix yet but plan to. I'm not sure if the toilet needs to be pulled or if it can be accessed from the carpeted panel on the back.
Before I do it I will call Thetford again to get a better understanding of the fix.

boowho · 08-04-2015, 04:42 PM

Quote:

Originally Posted by Phil57

Boo if I understand correctly the issue is the water drains out of the bowl. It has nothing to do with tank levels. Correct? If so mine does the same and. I have had the board replaced twice and FR replaced the toilet and still the same. No matter what I do the water will not stay in the bowl but to confuse the issue it works correctly sometimes. Nothing but fun.
The fix according to Thetford is to use a wire tie to hold the discharge hose up higher. I haven't done this fix yet but plan to. I'm not sure if the toilet needs to be pulled or if it can be accessed from the carpeted panel on the back.
Before I do it I will call Thetford again to get a better understanding of the fix.

Yes, the water that comes INTO the bowl AFTER a flush will not stay in the bowl, but drains out immediately; making gurgling and belching sounds as the bowl goes totally empty. FUN..... hate it when I have visitors!!!

But only does it when my black tank is full or nearly so. I really think that the black tank being full (or nearly full) is creating a vacuum somehow.

I've dropped a note to Randy to see what FR may know about it. I'll post back when I hear from him.

Boowho??

Phil57 · 08-04-2015, 05:07 PM

Boo that is what mine does although I never associated it with the tank being full. I plan to call Thetford again to get better instructions. I do know that as of last year no one at FR new about any fix.

Phil57 · 08-04-2015, 07:00 PM

Well Boo forget all the BS I just said. I tore mine apart ant the discharge hose they are talking about is set above the water line in the bowl. I did make it a little taller and it had zero effect on it. I will call them tomorrow. I did notice that the touch pad is cracking. That is a side note and has no bearing on the issue. I also don't seem to be able to adjust the water level in the bowl. I haven't done it in awhile so I have no idea what is up with that. I guess I will add it to the Goshen list.

boowho · 08-04-2015, 07:09 PM

Quote:

Originally Posted by Phil57

I tore mine apart ant the discharge hose they are talking about is set above the water line in the bowl. I did make it a little taller and it had zero effect on it.

Right.... As long as the discharge pipe is above the water line, then it will not run out. That's basic.... Water always "finds it's own level".

That's why I KNOW a vacuum is sucking the water out. Well, ALMOST certain....

Boowho??

Phil57 · 08-04-2015, 07:15 PM

I checked and rechecked and I'm certain that my BT vent is working so there is no vacuum in mine. Out if ideas. I'll check with Thetford in the AM.

boowho · 08-04-2015, 08:47 PM

Quote:

Originally Posted by Phil57

I checked and rechecked and I'm certain that my BT vent is working so there is no vacuum in mine. Out if ideas. I'll check with Thetford in the AM.

OK, I'll wait until you find out something (maybe) at Goshen....

I still think it's vacuum..... Something has to PUSH the water out or PULL the water out. It's (should be) just that simple.

Thanks

Boowho??

Phil57 · 08-04-2015, 09:02 PM

Thinking out loud could a syphon cause the water to be sucked out? It's odd because since you have said the water is sucked out that's what it sounds like. Funny that in mine it happens 90% of the time on a solids flush and maybe 30%on a fluids flush. So if more water was being flushed it would be more likely to cause a syphon.
I did also have an issue with the yellow light not going out after a dump but After a thorough BY rinse the green finely came back. I do flush the BT very often so not sure if something hung up on a sensor.
Between the fridge not cooling the washer not spinning and the toilet not holding water I'm officially sick of working on motor homes.

15berkxl · 08-05-2015, 04:37 AM

Quote:

Originally Posted by Phil57

Between the fridge not cooling the washer not spinning and the toilet not holding water I'm officially sick of working on motor homes.

Now now Phil if you didn't have issues what would you write about lol.

Wayne

Phil57 · 08-05-2015, 08:57 AM

Quote:

Originally Posted by 15berkxl

Now now Phil if you didn't have issues what would you write about lol.

Wayne

I'll be happy to get back to complaining about nothing like I usually do. It's almost like work lately. LOL.

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