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CanberraOceanRacingClub / namadgi3

Maintenance management system for Namadgi 3
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Electric toilet pumps are not working -- losing prime #383

Closed smr547 closed 3 years ago

smr547 commented 3 years ago

These electrical macerating pumps were recently reinstalled - see #376 The pumps were working in Pittwater but seem to have lost prime at sea during the delivery passage North. Need to discuss this with Bill (@bullswool). @delcosta for info.

smr547 commented 3 years ago

Ops manager @PSARN will also be interested

smr547 commented 3 years ago

@peterottesen is on board with Steve Rouch and they are prepared to perform surgery on the pipes.

smr547 commented 3 years ago

Bill Lesley recommends installing a non return valve in the seawater inlet line just above the seacock (a specialist job -- needs to be high quality and double clamped because it is below the water line). He said lets try it on one toilet and see how it goes. Meanwhile we believe the toilets can be used by having a bucket of fresh seawater on hand to provide the flush.

Here is a video which gives some clues about the operation of the pump. Seawater is pumped into the bowl via an impeller/eccentric pump located at the top of the unit just under the rotary switch. With both inlet and outlet lines falling down from the impeller it is difficult to see how this arrangement can maintain prime.

Steve Rouch suggests that there may be a technique of restoring prime using the "strange vertical white tube" the runs from the lower pump housing to the upper pump. The purpose of this pipe is a mystery. We will investigate further required.

@peterottesen is on board and will be interested.

smr547 commented 3 years ago

I forget to add: Effluent is pumped out of the bowl by a separate impeller and macerator blade located at the base of the unit. The output of this pump goes to the holding tank. The white tube is doing some magic by connecting the two chambers -- it is the missing link.

@peterottesen

smr547 commented 3 years ago

Lots of related info on the web -- search "jabsco electric toilet pump bleed tube"

This thread is worth studying.

@peterottesen

smr547 commented 3 years ago

@peterottesen here is the definitive manual for that pump

smr547 commented 3 years ago

Steve Rouch and @peterottesen report that they have solved the problem and have developed a procedure to

A procedure will be written and owners notified by "Notice to Skippers". Well done crew!!

I'm beginning to think that the root cause of this problem is the salt water feed line from the hull fitting to the flush pump is too long. The plumbing diagram in the definitive manual for the pump shows a very short run. An airlock in a short pipe is MUCH easier to clear compared to a long pipe airlock. Note that (in the plumbing diagram) the anti-syphon vents are provided by upstream loop -- not in the main feed pipe.

We will leave this issue open pending the SOP and also a review of the plumbing.

@delcosta @PSARN and @bullswool will be interested in the progress made.

smr547 commented 3 years ago

Hi Bill,

Thanks for letting me know. I agree with the idea of shortening the feed line so that the installation matches the Jabsco manual. It will be interesting to see the result.

I'd be more comfortable with installing the anti-syphon loop as recommended in the manual. The risk of someone forgetting to close the valve is too great. I can't help thinking that the high loop might also help maintain the prime in the flush pump. At the moment gravity is pulling all the water out when the boat goes on a heel.

Anyway, much of this may be moot for now. I've just heard from Peter Ottesen and they are sick of playing with toilets. They are planning to replace one of the electrical pumps with a manual pump. It's good to have such a capable crew on board!

Talk soon and thanks again.

On Thu, 13 May 2021 at 12:25, bill&margot @.***> wrote:

Hi Steven,

             I spoke to Steve Rouch a short time ago, they are a

couple of hours out of Coff’s Hbr.

             They have not had any success with the electric flush

pumps, and are seriously

             considering refitting the manual pumps. I suggested they

purchase a suitable short

             length of hose  when they get there, set up the

configuration shown in the Jabsco

             pamphlet on one of the toilets, and see how it goes.

             ( we could dispense with the vented loop altogether,

provided the seacock is closed

                after each use, to avoid the possibility of flooding

the boat.)

Cheers, Bill

smr547 commented 3 years ago

Aft starboard electric pump has been replaced with a manual pump and is now working reliably

smr547 commented 3 years ago

I’ve looked closely at this problem during my time on Namadgi over the past 3 weeks. Using a manual pump installed in the aft port heads I made the following observation — While pumping seawater into the bowl with the boat was on a port tack, the pump was drawing air 60% of the time. This was as a result of the inlet seacock being so close to the waterline — the slight heel of the boat lifted the seacock out of the water.

While this a mere inconvenience for the Jabsco manual pumps it will be a show-stopper for our electric pumps. These pumps are unable to draw seawater once air has been introduced to the feed pipe.

My observation supports Bill Leslie’s conclusion that these pumps are unsuitable for installation on Namadgi — at least in the aft heads.

It remains to test the electric pump in the forward heads before consigning these pumps to E-bay and closing this issue.

@bullswool @delcosta @pjwain will be interested

delcosta commented 3 years ago

Thanks Steven That makes sense.

Regards, Sam DeLorenzo Mobile & WhatsApp: +61 411 165 835 PO Box 3553, Manuka ACT AUSTRALIA 2603

IMPORTANT This e-mail and any accompanying attachments are intended for the sole use of the addressee(s) and may contain confidential information. If you are not the intended recipient (or authorised designee), please disregard the contents of this e-mail, notify the sender immediately and destroy all copies of this e-mail.

From: Steven Ring @.> Sent: Tuesday, 6 July 2021 17:15 To: CanberraOceanRacingClub/namadgi3 @.> Cc: Sam Delorenzo (Delorco) @.>; Mention @.> Subject: Re: [CanberraOceanRacingClub/namadgi3] Electric toilet pumps are not working -- losing prime (#383)

I’ve looked closely at this problem during my time on Namadgi over the past 3 weeks. Using a manual pump installed in the aft port heads I made the following observation — While pumping seawater into the bowl with the boat was on a port tack, the pump was drawing air 60% of the time. This was as a result of the inlet seacock being so close to the waterline — the slight heel of the boat lifted the seacock out of the water.

While this a mere inconvenience for the Jabsco manual pumps it will be a show-stopper for our electric pumps. These pumps are unable to draw seawater once air has been introduced to the feed pipe.

My observation supports Bill Leslie’s conclusion that these pumps are unsuitable for installation on Namadgi — at least in the aft heads.

It remains to test the electric pump in the forward heads before consigning these pumps to E-bay and closing this issue.

@bullswoolhttps://github.com/bullswool @delcostahttps://github.com/delcosta @pjwainhttps://github.com/pjwain will be interested

— You are receiving this because you were mentioned. Reply to this email directly, view it on GitHubhttps://github.com/CanberraOceanRacingClub/namadgi3/issues/383#issuecomment-874519796, or unsubscribehttps://github.com/notifications/unsubscribe-auth/AHK6QYQFBGF52K4QOML76KDTWKUPNANCNFSM44XC5SPA.

smr547 commented 3 years ago

Experience has shown that Namadgi 3's water intake lines are often exposed to the air and the electric pumps easily loose prime. A non-return valve is an option but unlikely to solve the problem. We should abandon the idea of having electric toilet pump on N3. Closing this issue.