Jabsco toilet bowl backfilling

[vyv_cox]

Although the joker valve is the prime suspect, I don't think that it is proven that the filling is back-filling. If the bowl fills with the lever in the 'dry' position, then back-filling is the reason, but if the lever is left in the 'wet' position, then syphoning can occur on the inlet side too.

The smell derived from the upward leg of the loop usually gives it away

 

[RupertW]

The smell derived from the upward leg of the loop usually gives it away

Alas so every time for us - sometimes slightly less bad if we have been a few days without using the holding tank.

A good joker valve pregents backfilling completely whatever the setting of lever or twist and lock.

 

[johnalison]

The smell derived from the upward leg of the loop usually gives it away

It must have been my recent cold that prevented me from smelling the OP's loo. I take it that it got through to you?

 

[Heckler]

Joker valve certainly the main one, but it seems like a case of belt and braces. The two valves are in series for water trying to come back the wrong way.

Pete

Quite right and in my experience the joker valve is just that, the flap valve is the real sealer. However! The twist and lock piston thing actually distorts the sealing face of the flap valve eventually and that along with calcium deposits stops it sealing properly and it back fills. I change my FLAP valve and clean everything up about every 18 months. It stops the bowl back filling.

 

[Heckler]

Alas so every time for us - sometimes slightly less bad if we have been a few days without using the holding tank.

A good joker valve pregents backfilling completely whatever the setting of lever or twist and lock.

The flap valve is a better sealer when it is not distorted. You do know how the twist and lock works dont you? The joker valve relies on head pressure to close the three flaps and hold then together, given that 27” of water head only gives 1 psi then you can see why they are a “joke” On my Bene even if the valves dont hold it never fills the bowl to the top so not much back pressure there to close it. On a Jeanneau 42 DS that I just delivered the outlet pipe is looped about 4 ft above the head and so,has more back pressure to close the joker.

 

[RupertW]

The flap valve is a better sealer when it is not distorted. You do know how the twist and lock works dont you? The joker valve relies on head pressure to close the three flaps and hold then together, given that 27” of water head only gives 1 psi then you can see why they are a “joke” On my Bene even if the valves dont hold it never fills the bowl to the top so not much back pressure there to close it. On a Jeanneau 42 DS that I just delivered the outlet pipe is looped about 4 ft above the head and so,has more back pressure to close the joker.

Amazing - I know the joker works perfectly until it fails about once a year per head and the old flap valves don’t do anything for backfilling and nor does the twist and lock. But different setups i guess and I’ll experiment by changing the flap valve when the joker next fails and be amazed if the twist and lock has any effect.