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Jabsco par max 3.5 problems


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Hi

We have a jabsco par max 3.5 which recently as been running on when the tap as been turned off for about 30 seconds a lot longer than normal. I have set the accumulator to 15 psi and cannot see any leaks around the pump. As anyone got any ideas of why it's running on for so long.

Thanks

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Plenty of voltage, just checked strainer which is clear. Accumulator as been on boat since we've lived aboard about 6 yrs history unknown prior to that how long does an accumulator last. Do I undoe the 6 Phillips screws to get to the pressure switch and chamber valve

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Personally I would first of all I would measure the pressure in the accumulator with the taps closed and the pump turned on but has cut out. That will give you the pressure the pump cuts out at. It might save you trying to strip the pump.

Also measure the voltage at the pump with it running, as per Rusty, because something may have developed a resistance.

Only after that think about stripping the pump and be aware that some of use have not had much success at making a leak proof job of it when rebuilding.

If the pump cut-out pressure is too high then rather than try adjusting the internal switch I would fit an external one like a D Square.

Remember to turn the tank stop cock off before trying to remove or strip the pump!

 

If 3.5 refers to the pressure then running the system at best part of 50 psi is not only far higher than most boats but will also be very close to the opening pressure of any calorifier PRV. If it opens then it may take a while for the pump to overcome the flow through the PRV and build pressure enough for it to shut off. If you are running at 3.5 bar then 15 psi in the accumulator is a bit low but rather than pressurise the accumulator I would turn the pump pressure down to about 2 bar/30psi.

 

Edited by Tony Brooks
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1 hour ago, Tony Brooks said:

If 3.5 refers to the pressure then running the system at best part of 50 psi is not only far higher than most boats but will also be very close to the opening pressure of any calorifier PRV. If it opens then it may take a while for the pump to overcome the flow through the PRV and build pressure enough for it to shut off. If you are running at 3.5 bar then 15 psi in the accumulator is a bit low but rather than pressurise the accumulator I would turn the pump pressure down to about 2 bar/30psi.

 

The 3.5 refers to the pump max flow rating of 3.5 gallons per minute

Edited by nbfiresprite
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37 minutes ago, nbfiresprite said:

The 3.5 refers to the pump rating of 3.5 litres per minute

The technical details say 13 litres a minute.

 

I had a similar issue last year on a similar sort of pump (Flojet Quad) . The pump was drawing air in. Fitting new O rings cured that.

I also found the electrical terminal under the cap  was corroded.

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On 4/9/2018 at 16:26, lesrollins said:

Hi

We have a jabsco par max 3.5 which recently as been running on when the tap as been turned off for about 30 seconds a lot longer than normal. I have set the accumulator to 15 psi and cannot see any leaks around the pump. As anyone got any ideas of why it's running on for so long.

Thanks

Just to add to the list of possible causes.

Have you introduced any air into the system recently eg by running out of water, adding plumbing. If so you could be compressing air somewhere in the system causing pump to run for longer?

What size accumulator? If you have recently adjusted it, I assume by pumping up the bladder, could it be it is now working normally and the 30 sec over run is the time to add the (6.5 litres of water, 30 secs of 13l/min) to the desired pressure within the accumulator tank.

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Just now, lesrollins said:

Well I took the pump off and made sure it was all clean and then tapped the end with the end of a screwdriver and everything is now working fine looks like the micro switch may of been stuck. Thanks for your help guys

It’ll happen again. Why not be proactive and buy an external pressure switch and wire (and plumb) it in at your leisure instead of waiting for it to fail completely. 

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Just now, WotEver said:

It’ll happen again. Why not be proactive and buy an external pressure switch and wire (and plumb) it in at your leisure instead of waiting for it to fail completely. 

They are far superior to those crappy micro switches imo. 

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