Electric Toilet conundrum

[Irish Rover]

I fitted a TMC electric toilet in each of the heads 2 years ago and both have worked well until recently. Now both are letting a small trice of water into the bowl which almost fills up overnight. There is no vent on either but they worked perfectly well for 2 years until recently. In fact the start of this problem coincided with relaunch after a week long liftout recently. Anyone have any ideas or suggestions?

 

[jiris]

In my experience, all f them start to leak water from the flushing inlet sooner or later (mostly sooner ). Instead of changing the valve every time it occurs, I simply installed a manual valve in the line and open it only when needed. Simple, if forgotten, not a big deal as the leak is normally only a small trickle. I gave a solenoid valve a thought, but rejected it eventually as an unnecessary complication.

 

[Ian_Edwards]

Assuming that the toilets are installed below the waterline, it's almost certainly it's water syphoning back into the bowl, either through the flushing water supply or the waste discharge hose.
The waste hose should have a vented loop and the vent may well be stuck closed, it is usually a simple, if smelly, task to take out and clean the rubber valve.
If it's syphoning back through the flushing water inlet, then there's either a non return valve or a vented loop depending on the installation. Cleaning the vent is as above, it's a little more difficult to clean the non return valve. Close the seacock and remove the valve for cleaning, although I have found the a gentle tap with a rubber mallet is often enough the free the flapper valve.

 

[vyv_cox]

If the water is smelly it is the joker valve. The lips of the valve tend to accumulate salts that prevent them closing. It is quite normal for the bowl to fill but not overflow when this happens. It is the contents of the upward leg of the loop.

 

[rogerthebodger]

I fitted a TMC electric toilet in each of the heads 2 years ago and both have worked well until recently. Now both are letting a small trice of water into the bowl which almost fills up overnight. There is no vent on either but they worked perfectly well for 2 years until recently. In fact the start of this problem coincided with relaunch after a week long liftout recently. Anyone have any ideas or suggestions?

I used to have a TMC converted head and this is the diagram of the motor pumps.

Impeller 29 is the flush water inlet pump and if this is damaged it could allow fresh water to enter the bowl.

Item 18 is the macerator impeller and if the piping is not setup with a syphon break raw water could syphoning back.

I ended up replacing my TMC with a Jabsco diaphragm pump and separate flush pump

 

[jiris]

...................................
If it's syphoning back through the flushing water inlet, then there's either a non return valve or a vented loop depending on the installation. Cleaning the vent is as above, it's a little more difficult to clean the non return valve. Close the seacock and remove the valve for cleaning, although I have found the a gentle tap with a rubber mallet is often enough the free the flapper valve.

Sorry, there can be neither non-return valve nor vented loop on the inlet line ;-). It just wouldn't work. In most cases there is an impeller pump in the line, similar to raw water pump on your engine. On this drawing https://www.tradingpost.com.au/Boat...ic-toilet-parts/Bensville/NSW/AdNumber=K9LM4T the impeller is fig. 27. Normally the impeller seals the the inlet like a valve and lets water in only when it is turning. Ideally...
Beside of the solution I described in my previous post, you can also move the bowl up so the rim is some height above waterline - as long as boat is not banked, it works .

 

[Irish Rover]

Thanks for the replies. It's definitely clean water from the inlet side. It stops leaking if I close the sea cock. The pump is installed below the waterline. I find it really strange that both started giving the same trouble at the same time directly after relaunching. I take fitting a vent on the inlet won't solve the problem?

 

[jiris]

Thanks for the replies. It's definitely clean water from the inlet side. It stops leaking if I close the sea cock. The pump is installed below the waterline. I find it really strange that both started giving the same trouble at the same time directly after relaunching. I take fitting a vent on the inlet won't solve the problem?

It is probably no coincidence. The pumps god dry and the dried dirt caused some scratches to the impellers. As for the valve, that is what I have done and what I suggested to do in my first post...

 

[LittleSister]

Sorry, there can be neither non-return valve nor vented loop on the inlet line ;-). It just wouldn't work.

The vented loop in the water inlet normally goes between the pump (whether manual or electric) and the bowl. Why can this not be installed in this case (i.e. in the pipe No. 47 in the diagram)?

 

[VicS]

Thanks for the replies. It's definitely clean water from the inlet side. It stops leaking if I close the sea cock. The pump is installed below the waterline. I find it really strange that both started giving the same trouble at the same time directly after relaunching. I take fitting a vent on the inlet won't solve the problem?

As Little Sister says a vented loop in the inlet must be fitted to replace the supplied hose between the pump and the inlet to the bowl. If you fit is between the inlet sea-cock and the pump it will simply allow air to be sucked in,

If you can do that it will solve the problem of water siphoning in via the inlet

You should also have a vented loop in the discharge pipework.
At present you are relying on the the valve in the outlet. Sooner or later it will suffer the same problems Vyv describes, but then it will be dirty smelly water that leaks back into the bowl

 

[Irish Rover]

After some more checking I think I have a different problem either side. Stb side is definitely clean water coming from the pump but the pt side may be foul water seeping back from the discharge hose. I understand the reason for the vent on the inlet hose and I'll try that as soon as I get somewhere to buy it. In the case of the discharge my tank is around 1 metre higher than the toilet bottom and the inlet is at the bottom of the tank. I'm assuming the tank inlet is a non return and my worry is the water in the discharge hose which is probably close to 2m in length. Would a vent sort this and where would I fit it?

 

[jiris]

The vented loop in the water inlet normally goes between the pump (whether manual or electric) and the bowl. Why can this not be installed in this case (i.e. in the pipe No. 47 in the diagram)?

Ops You are right, I was wrong. My mistake came from the fact, my system is so compact, it would be physically impossible (or at least very awkward) to fit it after the pump - so the only place I thought about was BEFORE it. In principle it should be O.K.

 

[Irish Rover]

Thanks again for all the advice last week. So the vented loop solved the vlean water filling into the bowl but I still seep back from the disco hose on the other side. The discharge hose is more than 2m long and enters the tank about 1m above the bottom of the toilet. Its 25mm hose. I don't understand how a vent would help or where to put it. Could I fit a n/r valve close to the toilet and if so what type? A solution might encourage my 2 female crew members to prolong our trip.

 

[VicS]

Thanks again for all the advice last week. So the vented loop solved the vlean water filling into the bowl but I still seep back from the disco hose on the other side. The discharge hose is more than 2m long and enters the tank about 1m above the bottom of the toilet. Its 25mm hose. I don't understand how a vent would help or where to put it. Could I fit a n/r valve close to the toilet and if so what type? A solution might encourage my 2 female crew members to prolong our trip.

If the discharge hose enters the tank above the level in the tank a vented loop is not going to help. What is in the hose will still leak back.

If the discharge enters the tank below the level in the tank a vented loop might help a bit but the water in the toilet side of the loop will still tend to leak back

The diagram Roger posted in # 5 appears to show a flap valve in the outlet ( part 23, I think ) Replacing that should solve the problem A Joker valve like Jabscos have would also do the trick if its possible to fit one. Either way replacing the valve is likely to be a regular job. ( cleaning it might be a temporary solution.)

More flushing will help to ensure anything that leaks back from the hose is relatively clean

For a non return valve you could try one of these Jabsco 29295-1000 - In-line non-return valve / Bilge Pump Accessories / Bilge Pumps / Pumps / Marine / Xylem JabscoShop - Jabsco & Rule Pumps and more - from the experts

 

[rogerthebodger]

Vic you a correct item 23 is a flapper valve

TMC Electric Toilet Spare Part - Flapper valve (23)

 

[Irish Rover]

Thanks guys. I think I'll try for the n/r valve when I'm in Marmaris at the weekend. If I attempted to take the pump apart I'd be doing the flapping myself and cursing the joker who invented it.

 

[VicS]

Thanks guys. I think I'll try for the n/r valve when I'm in Marmaris at the weekend. If I attempted to take the pump apart I'd be doing the flapping myself and cursing the joker who invented it.

Its only the outlet hose connection that you have to take off ( 3 screws ) to access the flapper. You'll just need gloves , 'cos it handles human waste, and something to catch the water that will leak out. .
Youll need both of these if you fit a NRV anyway plus something to cut the pipe.. Maybe hot water to soften the hose to fit onto the new NRV. You'll probably end up in a bigger flap than if you fitted new outlet valves
You'll be taking the more difficult route and you'll still need to service the NRV periodically as that will slowly scale up just the same Plus youll end up with a big ugly black dark coloured thing next to the toilet that will frighten the females.

Best solution ..... get rid of the females. ... personally never sailed with them.

 

[Irish Rover]

Thanks again guys. So the good news and the bad news. On the side that was letting foul water back from the discharge side I fitted a new flapper valve and, being Irish, and to be sure to be sure I fitted an inline n/r valve yesterday. All's good and it seems fine now. In the other head which was taking in clean water on the inlet side I fitted an anti syphon well above the toilet level but the bowl is still filling. I can fit a simple tap in the line as suggested but I'm not at all confident my teenage daughter who uses that particular facility will remember to open and close it. Any suggestions welcome short of getting rid of my female crew.

 

[VicS]

Thanks again guys. So the good news and the bad news. On the side that was letting foul water back from the discharge side I fitted a new flapper valve and, being Irish, and to be sure to be sure I fitted an inline n/r valve yesterday. All's good and it seems fine now. In the other head which was taking in clean water on the inlet side I fitted an anti syphon well above the toilet level but the bowl is still filling. I can fit a simple tap in the line as suggested but I'm not at all confident my teenage daughter who uses that particular facility will remember to open and close it. Any suggestions welcome short of getting rid of my female crew.

To be effective the antisiphon valve must be above the waterline , not just above the toilet bowl ( heeled waterline in the case of a sailing yacht). If it is not above the water line water will continue to siphon in.

See these Jabsco instructions Installation Instructions for Jabsco Manual Marine Toilet

The manual toilets have a weighted and lightly sprung valve in the pump head which will resist siphoning up to a point if the wet/ dry bowl selector is left in the wet bowl position but AFAIK your electric toilet has no such valve and only the flexible vane pump prevents siphoning. That's OK until it gets a little bit worn or tired

 

[Irish Rover]

To be effective the antisiphon valve must be above the waterline , not just above the toilet bowl ( heeled waterline in the case of a sailing yacht). If it is not above the water line water will continue to siphon in.

See these Jabsco instructions Installation Instructions for Jabsco Manual Marine Toilet

The manual toilets have a weighted and lightly sprung valve in the pump head which will resist siphoning up to a point if the wet/ dry bowl selector is left in the wet bowl position but AFAIK your electric toilet has no such valve and only the flexible vane pump prevents siphoning. That's OK until it gets a little bit worn or tired

Thanks. I've rechecked and the vent is at least 30 cm above the water line.