Jabsco 29200 recirculates dirty water

[Bashar]

I recently replaced 2 perfectly working manual jabsco head pumps with the 29200 electrical conversion kit.

When they flush to sea, all is fine. When they flush to the holding tanks (130cm higher than the pumps), some waste water gets mixed with the inlet feed and recirculates into the bowl.

I followed the advice of the installation manual and changed the pipe from the pump to the bowl so it goes vertically up to the level of the holding tank and then down to the bowl. That made the situation better, but did not completely solve the problem.

I am assuming I have no problems on the inlet side because the manual pumps worked just fine, and it is unlikely I will have the same problem in 2 different heads. Having said that, both inlets now have a filter that did not exist before, but surely that cannot make such a difference.

I have 4 questions:

1. Should the new pipe from the pump to the bowl be vented at the top? I can see that some bubbles move up from the bowl after flushing.

2. If not vented, is it better to have a tight U at the top or a wide one?

3. I am guessing the role of this new pipe is to equalise the pressure on both sides of the inlet pump. Is this correct?

4. Is it possible that the seals between inlet and waste on both pumps are now damaged? I have a week of continuous use before installing the new pipes.

Any other suggestion?

Thanks



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