TMC toilet is filling the bowl 24/7

[Karlsenkystfiske]

Even after the pump has stopped running water is flowing into the bowl. The system is not fitted with a hose bend above waterline on the intake side, like it should. But the boat is 10 years old and it has worked okay this far. So besides getting a longer hose on the intake, what would need replaceing? My knee jerk reaction is that the impeller could be bad, as a intact impeller should not let any water through the pump when idle.

 

[RunAgroundHard]

They have so called joker valve, a non return valve, fitted immediately after the bowl base, between the macerator and bowl base. If this is damaged it will allow back flow into the head via the discharge pump. The discharge pump and impeller will not seal, as they are not designed to do that. You therefore need to replace the joker valve to reinstate the head as currently installed.

 

[LittleSister]

Unless it's a Lavac, which you don't have, or the toilet is above the waterline - unusual in small boats - it 'should' have both the inlet and outlet pipes going up above the waterline (including when heeled - n.b. less height needed nearer the centreline), and an anti-syphon valve (quite cheap*) at the highest point in each pipe. The anti-syphon valve stops anything coming out of the pipe out when it's under pressure (i.e. when you're pumping), and allows air in - to break the syphon - when the pipe has negative pressure (i.e. when you stop pumping).

For your type of toilet (and most others apart from the Lavac) the inlet loop and anti-syphon valve goes between the pump and the toilet, not between the inlet and the pump.

Without an anti-syphon valve the water can flow (by syphoning) even if the pipe goes above the waterline.

As RunAgroundHard suggests, it is probably your outlet joker valve that's leaking and allowing water to syphon back into the toilet, but it could instead be that the seal has gone in your inlet pump (the inlet and outlet pumps are linked in the TMC and most other common toilets, so when you pump both are working, but they are actually two separate pump mechanisms for incoming water and outgoing waste water).

So long as both pumps seal OK and are in good condition, then you don't get water flowing into the toilet (except when you're pumping). The pipe loops and anti-syphon valves save you a terrible mess or sinking your boat if (or, rather, when) the pumps fail to seal. I've had boats with no loops and anti-syphon valves, and it was fine during my ownership, but sooner or later there would have been a problem, perhaps a catastrophic one.

Some people rely on closing the seacocks every time after the toilet is used, but that depends both on the seacocks being easily accessible, and everyone on the boat remembering every single time.

p.s. Example of suitable anti-syphon valve (other manufacturers & suppliers available) - n.b. you don't need for your toilet the much more expensive Vetus and metal etc. ones designed for engine cooling circuits .
Seaflow Plastic Vented Anti-Siphon Loop (19mm Hose) | ASAP Supplies

 

[Bodach na mara]

The last two answers both seem to be wrong in that the OP seems to suggest that the water filling the bowl is coming from the inlet. Us such the joker valve is not the problem as it lies between the bowl and the outlet pipe. Joker valves do give problems ( and don't see to last long on Jabsco toilet) and when they fail they allow the bowl to partly refill with stuff from the outlet pipe, which is not pleasant.

The position of the anti siphon device is in the inlet loop between the seacock and the pump. It can't be between pump and bowl because on Jabsco, Blake's and possible others the pump is part of the toilet unit and is permanently mounted next to the bowl. The inlet tube is connected to the pump inlet and the pump outlet is a short tube of about 6 " feeding into the bowl. No anti siphon loop here.

 

[LittleSister]

The last two answers both seem to be wrong in that the OP seems to suggest that the water filling the bowl is coming from the inlet. Us such the joker valve is not the problem as it lies between the bowl and the outlet pipe. Joker valves do give problems ( and don't see to last long on Jabsco toilet) and when they fail they allow the bowl to partly refill with stuff from the outlet pipe, which is not pleasant.

The position of the anti siphon device is in the inlet loop between the seacock and the pump. It can't be between pump and bowl because on Jabsco, Blake's and possible others the pump is part of the toilet unit and is permanently mounted next to the bowl. The inlet tube is connected to the pump inlet and the pump outlet is a short tube of about 6 " feeding into the bowl. No anti siphon loop here.

Harrumph!

I specifically said it could be coming via the inlet
The OP did not say it was coming via the inlet, though seemed to assumed it was (without any evidence provided - a syphon on either inlet or outlet would result in water coming into the toilet. If you get foul water coming in, you obviously didn't pump enough when flushing! ).

It can't be between pump and bowl because on Jabsco, Blake's and possible others the pump is part of the toilet unit and is permanently mounted next to the bowl. The inlet tube is connected to the pump inlet and the pump outlet is a short tube of about 6 " feeding into the bowl. No anti siphon loop here.

You are wrong!

And on both points!
1) Put the anti-syphon loop between seacock and pump and you will struggle to pump any water in - it will just suck air!
2) The pump on a Jabsco, TMC etc. (I can't remember details of the Blake) is indeed permanently mounted next to the bowl, but it has a pipe between the pump and the bowl for the incoming flushing water. It is that pipe which needs to be replaced by a longer pipe with an anti-syphon loop and valve, as clearly shown in the manufacturers' instructions. The separate pump inlet pipe from the seacock does not need, and should not have, an anti-syphon loop & valve.

(Only the outlet flows 'internally' (i.e. without an external pipe) between the bowl and the pump housing. The outlet anti-syphon loop and valve should be placed in the outlet pipe between the pump and the outlet seacock.

 

[Bodach na mara]

Thanks LittleSister, I have sailed on a few boats with Jabsco toilets (and always hate them) an currently own one. They have never had a loop in the pipe between pump and bowl despite being installed below the waterline and have always used the wee short pipe supplied with the toilet and seemingly permanent but as people say "Every day is a school day." I have looked at the Jabsco toilet manual and you are absolutely correct. Thanks for the information, and for adding another job to the winter layup list!

I might just replace the Jabsco with a Lavac that I have in the attic at home. The Jabsco joker valves need renewed every year it seems. I never seem to get a second year without back leakage and they are a pig to remove and an even bigger pig to replace.

 

[Karlsenkystfiske]

Wow. This is already more than I couldehave hoped for. Thanks guys
So I will order syphon valves and some hose. I see that it is possible to install the syphon valve between pump and bowl, but what is the benefit of doing so? I would rather hide it away in the technical room if that is an option.
And yeah, I think the joker valve is gone. I have seen things coming back up

 

[RunAgroundHard]

Have a look through this lot, it explains stuff to install and maintain the TMC heads: -

http://webserver.flak.no/vbilder/06612.pdf
http://www.five-oceans-images.com/articulos/1560/1560_M01.pdf
https://static.watski.com/files/marin-toalett-elektrisk-112987-11pFA.pdf

 

[FWB]

Trying to remember the set up on my boat which has the head well below the waterline.
The inlet from the seacock goes up to an anti syphon loop above the waterline and from there to the pump. Similarly for the discharge.
It does mean that you have to put your finger on the hole on top of the inlet loop to allow water to flow in as you pump. This is straight forward on my boat and everyone knows the drill.
This ensures that both seacock pipes are well above the waterline at the loops. Belts and braces maybe but it is a safe set up.

 

[LittleSister]

I see that it is possible to install the syphon valve between pump and bowl, but what is the benefit of doing so? I would rather hide it away in the technical room if that is an option.

It is not just possible, but necessary to install the anti syphon loop and valve between the pump and bowl (if you are going to have one at all). If you want the inlet upwards loop somewhere outside the toilet compartment, you will have to run the pipe from the pump out of the compartment to the loop and valve, and then back in again to the bowl. (By contrast the outlet loop and anti-syphon valve does not have to return to the compartment (unless that is where the outlet seacock and skin fitting is).)

Only that section of the incoming water pipework after the pump (and before the bowl) is under pressure when you pump, which is what closes the anti-syphon valve until you stop pumping. The section of pipework between the seacock and (before) the pump is, by contrast, under suction when you pump, so you will draw in air through the anti-syphon valve and as a result get little little or no water to the toilet (and/or have to pump excessively to get the amount of water you need).

(Just to be clear, the point of the upward loop of pipe is to to provide a place to fit the anti-syphon valve above the waterline (outside the boat) at all times, even when heeled, If you only do that loop, without the anti-syphon valve, it does not provide security - the water can still run up the pipe above the waterline then down again by the syphon effect. To make it effective you must put an anti-syphon valve at the top of the loop (they are usually made into a curved section of solid pipe to facilitate that). When you stop pumping the weight of the water in the pipe work opens the valve and draws air in. It is the air gap that exists in the pipework above the waterline that prevents syphoning occurring.)

 

[Neeves]

I'm amazed we have a Jabsco toilet, one manual one with a TMC motor, that I added. After over 20 years stalwart service we have never replaced the joker valve. Both toilets are above the waterline.

The only issues have been when someone put something in the toilet that had not been eaten and the impeller blocked.

On our X-99 we it had the ability to syphon, on port tack, and fill the bow bilges. The solution was to turn the inlet sea cock off.

As mentioned if the contents back fill - then you have not pumped sufficiently long enough and your next problem will be calcification of the pipes. Pump for longer (depends on the length of the outlet pipe, which are commonly very short).

Jonathan

 

[chrishscorp]

We had a TMC manual toilet on our old boat the cost of a service kit was 2/3rds the cost of a new Jabsco, and getting hold of the parts when needed is not so easy.
If the bowl is refilling it is likely the joker valve or the bottom flap valve if they are not serviceable and its a manual loo then consider all your options.

 

[Karlsenkystfiske]

We had a TMC manual toilet on our old boat the cost of a service kit was 2/3rds the cost of a new Jabsco, and getting hold of the parts when needed is not so easy.
If the bowl is refilling it is likely the joker valve or the bottom flap valve if they are not serviceable and its a manual loo then consider all your options.

I am not familiar with the bottom flap valve? The joker valve is leaking for sure. But the bowl is also filling from the top when the discahrge over board valve is closed.

(Just to be clear, the point of the upward loop of pipe is to to provide a place to fit the anti-syphon valve above the waterline (outside the boat) at all times, even when heeled, If you only do that loop, without the anti-syphon valve, it does not provide security - the water can still run up the pipe above the waterline then down again by the syphon effect. To make it effective you must put an anti-syphon valve at the top of the loop (they are usually made into a curved section of solid pipe to facilitate that). When you stop pumping the weight of the water in the pipe work opens the valve and draws air in. It is the air gap that exists in the pipework above the waterline that prevents syphoning occurring.)

Thank you for spelling it out to me!I will fit an anti syphon valve on both inlet and outlet! Dont want the toilet sinking the boat

 

[FWB]

Thank you for spelling it out to me!I will fit an anti syphon valve on both inlet and outlet! Dont want the toilet sinking the boat

See my post#9
You will need to put your finger on the inlet valve when pumping, otherwise it won’t draw water in. Not a problem, just a routine thing to do.
No need to do it when discharging.

 

[LittleSister]

See my post#9
You will need to put your finger on the inlet valve when pumping, otherwise it won’t draw water in. Not a problem, just a routine thing to do.
No need to do it when discharging.

You do not need to put your finger on the valve to pump, unless you have put the valve (and loop) in the wrong part of the inlet system!

If the valve is between the seacock and the pump, it will cause the problem you mention (as I pointed out in previous posts).

That is why the manufacturers' installation instructions (and my posts above) explicitly tell you to put the raised loop and valve between the pump and the toilet bowl. If it is in that correct position, the pressure caused by pumping closes the valve (no finger required!) and holds it there. When you stop pumping, the pressure falls and the valve opens, letting in air and preventing water from syphoning into the toilet.

Between the seacock and the pump all that is needed is a direct, closed pipe. A loop in this section is wholly unnecessary, and an anti-syphon valve in this section is plain wrong.

Note the above applies to the typical marine toilet layout as used by Jabsco, ITT, Par-Brydon, TMC, Blakes, etc. (but not to Lavacs, which function differently).

 

[FWB]

Yes I have deliberately put the valve there in the “wrong part” for safety reasons. The pipes from the seacock go up well above the waterline to the loops.
The toilet bowl is about 18inches below the waterline and its base is level with the seacocks.
Yes this means that the pump will suck air not water from the inlet unless the valve is covered. In my case it’s straightforward. There is no way that water can be siphoned into the toilet.

You do not need to put your finger on the valve to pump, unless you have put the valve (and loop) in the wrong part of the inlet system!

If the valve is between the seacock and the pump, it will cause the problem you mention (as I pointed out in previous posts).

That is why the manufacturers' installation instructions (and my posts above) explicitly tell you to put the raised loop and valve between the pump and the toilet bowl. If it is in that correct position, the pressure caused by pumping closes the valve (no finger required!) and holds it there. When you stop pumping, the pressure falls and the valve opens, letting in air and preventing water from syphoning into the toilet.

Between the seacock and the pump all that is needed is a direct, closed pipe. A loop in this section is wholly unnecessary, and an anti-syphon valve in this section is plain wrong.

Note the above applies to the typical marine toilet layout as used by Jabsco, ITT, Par-Brydon, TMC, Blakes, etc. (but not to Lavacs, which function differently).

 

[LittleSister]

Yes I have deliberately put the valve there in the “wrong part” for safety reasons. The pipes from the seacock go up well above the waterline to the loops.
The toilet bowl is about 18inches below the waterline and its base is level with the seacocks.
Yes this means that the pump will suck air not water from the inlet unless the valve is covered. In my case it’s straightforward. There is no way that water can be siphoned into the toilet.

There is no way that water can be siphoned into the toilet if you put it where the manufacturers tell you to put it!

By all means put you loop and valve where you want put it - it's your boat - and live with the consequences, but please don't come on here giving misinformation to people who are asking for helpful advice.

 

[FWB]

There is no way that water can be siphoned into the toilet if you put it where the manufacturers tell you to put it!

By all means put you loop and valve where you want put it - it's your boat - and live with the consequences, but please don't come on here giving misinformation to people who are asking for helpful advice.

With the heads below the waterline there is still the possibility of siphoning to the pump. I have eliminated that possibility.

 

[LittleSister]

With the heads below the waterline there is still the possibility of siphoning to the pump. I have eliminated that possibility.

It can syphon to the pump all it likes, but the pump is enclosed, and the loop and valve stands between it and the bowl, so water can't get to the bowl and flood your boat.

Your arrangement is contrary to what the manufacturers, the surveyors, and the Boat Safety Scheme promote, and gives you the faff of manually stopping the valve.

You may just as well have a hole in your pipe, as the valve in your arrangement is doing nothing at all for you - it never closes!

As I said,. do what you like on your boat, but please stop spreading misinformation to those looking for advice.

 

[FWB]

It can syphon to the pump all it likes, but the pump is enclosed, and the loop and valve stands between it and the bowl, so water can't get to the bowl and flood your boat.

Your arrangement is contrary to what the manufacturers, the surveyors, and the Boat Safety Scheme promote, and gives you the faff of manually stopping the valve.

You may just as well have a hole in your pipe, as the valve in your arrangement is doing nothing at all for you - it never closes!

As I said,. do what you like on your boat, but please stop spreading misinformation to those looking for advice.

I don’t need a lecture.
The pump on my boat is isolated from the sea until commanded. No seawater can get above the waterline in the heads without my making it do so. I can safely leave the seacocks open should I wish to.
A safety feature that I’ve had for twenty years and one suggested by the builder.