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Old 04-18-2017, 03:00 PM   #1
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Replace 40psi Fresh Water Pump with 50psi

Our old (original I believe) Jabsco pump is leaking, and I'm not throwing any more money at it.
It's the type that has a diaphragm and is driven by an external belt.
I picked up a new Jabsco Par-Max 2.9gpm that says "Up to 50 PSI" on the box, but now that I look at it and read the specs, it's not adjustable.
You can get 30, 40, or 50PSI.

Problem is, the old pump says 40PSI, and is run through a small accumulator.
Am I asking for trouble with the 25% (40 to 50) increase in pressure?
Maybe the system can handle it, but I sure don't want to be popping hoses and fittings off.

Thanks.
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Old 04-18-2017, 04:12 PM   #2
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Old 04-18-2017, 06:23 PM   #3
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Where you set the pressure switch is what counts.
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Old 04-18-2017, 06:33 PM   #4
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It doesn't look adjustable.
Remove and replace is what the manual shows, and at $40+ for a new switch, I'd just as soon get the proper pressure in the first place.

Here's the manual:
http://www.pumpagents.com/pdf/Jabsco...31395-0392.pdf
Not only does it show individual pressure switches (25,40,50psi) but also individual pump head assemblies as well.

Now, on the other hand, if you know of another way to adjust the pressure on this pump...
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Old 04-19-2017, 06:27 AM   #5
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On most pumps the running water delivery to an open faucet will not change , as all the pump guts inside are the same , only the pressure switch is different.

IF you want pressure and volume at the same time an upgrade , Galley Maid or Paragon might be used.

There not found in the bargain bin, and with a 1/4 or 1/3 HP motor the electric draw operating will be much higher.

Most folks need higher volume , not higher pressure , except for deck washing where both are great.

Water Pressure Systems - Galley Maid

www.galleymaid.com/water.htm


MARINE PRODUCTS ... Galley Maid Macro-B Super Water Pressure System, especially designed for large pleasure or work boats. Operating pressure settings ... Galley Maid HI-Pressure Washdown Pump, for fresh or salt water applications.
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Old 04-19-2017, 05:26 PM   #6
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Thanks for the replies. I'm not looking to upgrade as much as I just want the new pump to be compatible with the rest of the existing system.
We didn't have a problem with either volume or pressure before, and I'm sure it'll be even better since I've replaced 2 of the 3 sink faucets with "Water Sense" water saving fixtures.
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Old 04-19-2017, 07:46 PM   #7
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Please be aware that you are replacing a pressurized stored water system with an "on demand/ flow controlled" pump system. In other words your previously used pressure switch along with your accumulator tank are no longer necessary and /or should not be incorporated into your new pump system. Your pump will not cycle on and off as you have experienced with your old system. It is a variable speed type pump, sensing flow demand and adjusting speed accordingly.
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Old 04-20-2017, 06:05 AM   #8
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"It is a variable speed type pump, sensing flow demand and adjusting speed accordingly."

Perhaps , most of the small ones I have seen bypass inside to allow the pump to operate at low flow.

This uses electric for no purpose , something to think about if anchoring out is your thing.

With a larger (2gal+) accumulator there is no wasted electric and the pump system will deliver silent water in modest quantities.
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Old 04-20-2017, 07:59 AM   #9
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Quote:
Originally Posted by FF View Post
"It is a variable speed type pump, sensing flow demand and adjusting speed accordingly."

Perhaps , most of the small ones I have seen bypass inside to allow the pump to operate at low flow.

This uses electric for no purpose , something to think about if anchoring out is your thing.

With a larger (2gal+) accumulator there is no wasted electric and the pump system will deliver silent water in modest quantities.
I am not exactly sure how much electricity is used for no purpose. The pump is only on at a very slow speed if there is a very low flow. It does indeed shut off when there is no flow. The trick is not to have any drips or small leaks. In regards to your "modest quantities" of water used without an electric demand being called for from the standard pump/pressure switch/accumulator tank, I would provide that Boyles Law applies. Given the total volume of 2 gallons in the accumulator tank about 5 quarts will be water and 3 quarts air. At a pressure setting of 30-50 psi 2 quarts of water draw will activate the pump. So about 2 quarts is your modest amount. As that applies to boating - A good pot of coffee.
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Old 04-20-2017, 11:17 AM   #10
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Quote:
Originally Posted by ulysses View Post
Please be aware that you are replacing a pressurized stored water system with an "on demand/ flow controlled" pump system. In other words your previously used pressure switch along with your accumulator tank are no longer necessary and /or should not be incorporated into your new pump system. Your pump will not cycle on and off as you have experienced with your old system. It is a variable speed type pump, sensing flow demand and adjusting speed accordingly.
Yea, I have one of those "variable speed" pumps that's not supposed to need an accumulator tank. It chattered at low volumes. Adding an accumulator tank fixed that problem.
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