Shower drain pump Mystery.

[The_Gaffer]

Do pigs fly...'of course they don't, its an expression stupid!!!'  

The stand up shower on board The Gaffer has a drain pump fitted to pump out the water from the shower tray.  This pump, a normal Utility pump, has been fitted in the same place, with the same wiring circuit, using the same drain pipes ever since I've had the Gaffer, never needed any attention, so never touched it.  When I launched the Gaffer for this season, I noticed that the pump was not pumping out the remaining water in the shower tray.  Indeed, instead of pumping out the water, it was actually pushing it back in.  I suspected that the impeller had worn out, and bought a new one to fit in at the 1st opportunity.    On Tuesday, while I was attending to changing the fuel filters, I bought a new impeller for the pump and replaced the one I had.  Same thing happened, pump wasn't sucking out the water from the shower tray, but rather pushing it back in.  So, just to satisfy my curiousity, I changed the directions of the inlet/outlet pipes.  Behold, the water was pumped right out of the tray.  Unbelievable, but true.  I've had this pump fitted for 7 yrs, always worked well.  Suddenly, and for no apparent reason, it decides to chage pump directions.  This is not a case of reversed polarity, I tried that too on Tuesday, the pump did not operate.  So, my big question to you guys is...'' ANYBODY OUT THERE WHO UNDERSTANDS 12V DC PUMPS AS TO WHY THIS PHENOMENON SHOULD HAPPEN.  DO PIGS REALLY FLY

[nando_s]

The only way to reverse the direction of a DC motor is by reversing the inputs, no other way unless there is complex drive circuits which i highly doubt in this application. Otherwise you accidentally swapped the plumbing connections, these things happen.

Although i kinda like the idea of flying pigs coming and swapping the hoses themselves, maybe we could ask the flying pigs to send in the Alungi this Sat 

[The_Gaffer]

I swear on all the tea in China, that I never even looked at the pump before this happened.  Thats the mystery.  No complex circuitry.  From DC 12v distribution board outlet to pump switch, to pump.  Negative earthing to earthing block.
Guys I'm not joking about this...I never looked at the pump , never mind swapping hoses!!!.  However, I am a mechanical engineer by trade...and things like this do not happen on their own.  There has to be an explanation for all this.  Something made this pump reverse its rotation...I also checked the curcuit just to make sure that it was the 12v DC cable coming from the distribution board that was energised.  It was.  This eliminates the idea of reversed polarity by colour scheme...i.e. red for energised live, black for negative grounding.

[robby017]

must be the lost soul of an alonga of season's past you caught!!!!!!!!

[Moonwalker]

Maybe on Monday during the alungi trip someone got bored and spent some time fiddling with the pump Check that the Red wire is connected to the + terminal on the pump.

[robby017]

wasn't me... i don't see myself fitting in to were the pump is... , (might have been Mario, he said he had a 'good feeling' on our way out.... maybe it was your pump that he felt!!!!!!      just kidding Mario!! 

[guido99]

Wasn't me i was minding my own biz 
BTW its Mike not Mario

[robby017]

dik to hide your true identity kienet

[EmicMalta]

try to figer out who was with you last time and will be competitor in the alungi competition. Someone is trying to put you down 


only way it can happen is due of reverse polarity in supply. This can even happen if it uses the diodes. If they get a shorted in a way that can bypass them , then this is the reason. I saw some of them that doesn t have colour code on the wire but then the rectifier system will set it up for you. In your case I think that it s much more this is the problem. Better thing is to take it out, remove the diodes, and make sure that you give according supply. Some of them use this rectifier even cos there are boats useing 24Vdc so one for all.

If keeps having problems call me and will come for a visit tomorrow.

I have some tooth pain so cannot dive which means that I'm available on land   

[Moonwalker]

Its almost impossible that a rectifier shorts in a way that it gives reverse polarity. But if there is the supply with correct polarity going to the pump than that may be the only reason. You have to open the pump to be sure.

[robby017]

has the mystry been solved joe ?

[The_Gaffer]

Sure.  Being mechanically minded, I reasoned  that what goes in must come out, and what comes out must have an inlet.  So I reversed the inlet/outlet pipes.  Pump works perfectly.  But....(There must always be a but  )  the pump had always worked perfectly before I reversed the pipes

[robby017]

thus the mystry remains........... jien nibqa nghid, xol mike kienet, meta hass xi haga ahna u hiergin al alungi..... lol   just kidding mike.

[ramio]

Goe the supply switch over is number 1 guess. The rectifier this works when on mains, so even if it bust, when you work on the battery supply the pump should go back to normal rotation.

Unless you prove the terminals along the way havn't been changed, I think that it may be a quetion of the permanent magnets inside the motor have reversed polarity. It may sound strange, but i saw it happen to a motor once.

[Moonwalker]

You may find it difficult to sell the Gaffer with gosths onboard