Leaking toilet flush valve

[bazza44]

Our van has a Thetford c200 toilet fitted, it has NO cistern for flush water. The flush water is drawn from main van tanks when flush button is pressed. The van has been sitting for 11 months not being used and I always remove the cassette when van not being used so seal is not compressed ( I think this helps retain shape ).

In it's place I put a 4ltr container under the bowl outlet for  "just in case"  and as it turns out just as well I did. Last Sunday I went to remove the 4ltr container and put the cassette in place as we were leaving Monday morning and found the container full and overflowing with water, damn what to do leaving in the morning ! After cleaning up I felt around up under the bowl where the Thetford hoses are but they were dry and after thinking about this I realized the water could only have come from the bowl outlet, this means flush water.

When the van is sitting at home I open up and turn on pumps and taps to let water run through every month or so and then when finished turn pumps OFF and depressurize a bit by turning one tap on for a second or so.

Some how the flush water valve ( Thetford 23709 ) has been opened and water has been pumped through with the remaining pressure in line. With no way to turn off water to toilet I took bits and pieces with me to enable cutting the Thetford hose and blocking it and then use a dipper for flushing if needed.

It all worked fine on park water connection until coming home and stopped for a cuppa on side of road, saw water on van floor near toilet, it must have leaked flush water into bowl and van movement through it out over bowl, Pumps were turned off.


I am going to remove toilet and take it inside my shed and set it up with a temporary pump etc and try, but the only thing I can think of is a faulty water flush valve that opens under a little pressure sometimes. Has anyone come across this before.

Barry

[gerrym]

Barry, did you remove the anode from your HWS while in storage?  Assuming it is a Suburban.

These are always helpful:

carac.com.au/products/john-guest-12mm-push-on-shut-off-value-suits-12mm-tube?variant=40414629920903&currency=AUD&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&gad_source=1&gclid=CjwKCAjwz42xBhB9EiwA48pT7yQ1NX7cnECnaqbkYxojJB3HMUkIA_tU9uVVkQSM8M3MrjKIrUfDIxoC1eEQAvD_BwE

This may be some help: 

Or: 

[bazza44]

Thanks Gerry, I have already seen those speedfix shut off valves and will be installing one in the line to toilet, it will have to be under the van as no room in the toilet body. Yes watched those videos and decided to take the toilet out of the van and then I can put it to any height and turn it to any angle to make it easier for my back.

Maybe there is a bit of grit in the valve. I will have to wait for rain to stop before starting toilet removal.

No I have never removed the anode from the hot water system when home, just replace when needed.

Barry

[gerrym]

Apr 21, 2024 13:29:24 GMT 10 bazza44 said:

No I have never removed the anode from the hot water system when home, just replace when needed.

Barry

Barry, the anode will increase your water pressure, even when not connected to the mains or pump not operating.

Probably no use in this case, but I have found the addition of food colouring helpful in spotting water leaks.

[spaceland]

Apr 21, 2024 13:36:05 GMT 10 gerrym said:

Barry, the anode will increase your water pressure, even when not connected to the mains or pump not operating.

Gerry, you have me intrigued. Please explain how the anode increases the water pressure?

[GerryP]

Sorry to butt in, but yes, it certainly does... to the point where the pressure relief valve on the unit can open.

The cause is that the continuous electrolysis between the anode and the tank, which protects the unit, creates a gas which eventually builds up pressure in the closed system. Normally, you probably don't notice as this gas is relieved when you open a tap. Have you ever noticed that the hot water tends to splutter a bit if you haven;t used it for a while? That's a buildup of gas in the HWS tank.

This is also why some people drain the HWS and remove the anode in order to prevent pressure buildup, but also to stop any electrolytic action and get extra life from the anode.

[gerrym]

Apr 21, 2024 17:20:32 GMT 10 GerryP said:

Sorry to butt in, but yes, it certainly does... to the point where the pressure relief valve on the unit can open.

The cause is that the continuous electrolysis between the anode and the tank, which protects the unit, creates a gas which eventually builds up pressure in the closed system. Normally, you probably don't notice as this gas is relieved when you open a tap. Have you ever noticed that the hot water tends to splutter a bit if you haven;t used it for a while? That's a buildup of gas in the HWS tank.

This is also why some people drain the HWS and remove the anode in order to prevent pressure buildup, but also to stop any electrolytic action and get extra life from the anode.

You have done your homework Gerry P.

There is also the small matter of the gas being flamable. (Hydrogen)

[bazza44]

Well GerryP and Gerrym you have given me something to think about. Although in my case don't forget that I open taps every now and then. Is there any indication of when gas is starting to build up ?

Barry

[GerryP]

Barry, only by opening the hot water tap occasionally, or if you see a wet patch on the floor under the pressure relief discharge.
Ours does the latter quite regularly parked in the shed.

[bazza44]

What you have said fits the symptoms Gerry. I have the toilet out and tested with temporary hook up but no leak yet. I wonder if the relief valve need replacing, I would not see any discharge because our van is under caravanport roof and water would fall onto ground.

I can get a new Thetford valve tomorrow and replace it anyway then maybe the relief valve and hope it is fixed.

Barry

[gerrym]

Apr 22, 2024 16:41:47 GMT 10 bazza44 said:

What you have said fits the symptoms Gerry. I have the toilet out and tested with temporary hook up but no leak yet. I wonder if the relief valve need replacing, I would not see any discharge because our van is under caravanport roof and water would fall onto ground.

I can get a new Thetford valve tomorrow and replace it anyway then maybe the relief valve and hope it is fixed.

Barry

Just a couple of thought bubbles Barry.

If the valve isn't leaking, why replace it?

Relief valves are safety devices, so they will discharge when the pressure builds up, but generally not all the time.

[gerrym]

Apr 23, 2024 8:01:16 GMT 10 gerrym said:

Apr 22, 2024 16:41:47 GMT 10 bazza44 said:

Just a couple of thought bubbles Barry.

If the valve isn't leaking, why replace it?

Relief valves are safety devices, so they will discharge when the pressure builds up, but generally not all the time.

Barry, probably a silly question, but I will ask it anyway.

Does the relief valve discharge water at all?

Your Suburban HWS, working on raising 20deg water to 60deg, without draw-off would discharge something like 350ml, under normal conditions.

You are probably aware that the HWS relief valve has two potential triggers. Temperature in case of thermostat failure and pressure.

If it doesn't discharge at all, then perhaps pressure build up could open the toilet solenoid valve, depending on design.

[jr]

Barry, can you exercise the HWS safety valve they usually have a little leaver on top that can be pulled up to force the valve open. Best test would be when hot and system under pressure but you need to be sure you are not in the firing line.
I would think if the toilet flush valve would be capable of handling a lot of pressure even to the point that a pipe joint would fail first.

JR

[bazza44]

I do use the trigger to let excess water out of the system now and again so I know it is not blocked but whether it discharges by itself I do not know. I can set a bucket under the suburban door to try and catch water.

I have the new Thetford valve so that will be eliminated now so other testing will be able to be done, also have a speedfit inline on/off tap for in the water line before the toilet so it can be isolated if necessary.

Thanks for your suggestions

Barry