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Old 13-04-2020, 05:22   #1
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Boost Pump Recommendation please (Watermaker)

I'm in the midst of a refit and replacing/relocating my pumps. What brand/specs of 12V Booster Pump are folks happy with for their watermaker? Mine is an older 20gph 120VAC system if it makes a difference.

Thanks in advance -

Peter
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Old 15-04-2020, 11:34   #2
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Re: Boost Pump Recommendation please (Watermaker)

Quote:
Originally Posted by mvweebles View Post
I'm in the midst of a refit and replacing/relocating my pumps. What brand/specs of 12V Booster Pump are folks happy with for their watermaker? Mine is an older 20gph 120VAC system if it makes a difference.

Thanks in advance -

Peter
Hi Peter.
If you can mount the boost pump totally below the water line then you can use a centrifugal non-self priming pump and I would recommend Jabsco Part No: 50850-0012

However most cruisers can't mount the boost pump below the water line, so in that case I would recommend what we use as our standard 12v Boost pump for a 20GPH water maker which is Jabsco Part No:42755-0092

For the self-priming pump, we have added a 12v cooling fan to the motor which reduces the operating temp by 50-degsF. A cooler 12v motor is a happier and longer lived 12v motor.

Cheers
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Old 15-04-2020, 11:52   #3
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Re: Boost Pump Recommendation please (Watermaker)

Would the jabsco belt driven 36800 work?
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Old 15-04-2020, 12:30   #4
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Re: Boost Pump Recommendation please (Watermaker)

A boost pump for a watermaker requires high flow, low pressure. These are surprisingly hard to find.
The Jabsco Third day mentioned is one option
A Johnson CM30 is similar.
Both are pretty expensive and the Johnson is hard to find in the US.

When my Johnson CM30 died on my 20GPH engine driven watermaker I tried a CM10 (lower flow rate) and there wasn't enough flow to keep the low pressure switch happy. After trying a bunch of other pumps I ended up going with a much cheaper Bosch Automotive 0392022010 which can be found anywhere.
It's flow rate is less than the CM30 at higher pressures but it works fine to keep the Pressure pump flooded even when my two pre filters are nearing the end of their life.

All the pumps I mentioned are not self priming but as Third Day mentioned keeping a self priming pump that works with the flow requirements of a watermaker probably necessitates a fan so it doesn't burn out. Find a way to install your pre pump below the waterline.

I have since started using the Bosch in my Hydronic heater circuit as well. Both have been very reliable despite long continuous run times with hot and corrosive fluids.
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Old 15-04-2020, 12:53   #5
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Re: Boost Pump Recommendation please (Watermaker)

Quote:
Originally Posted by motion30 View Post
Would the jabsco belt driven 36800 work?
Not being a "Guesser" I haven't personally tested that pump, so I can't say.
But here is what I DO KNOW.
We have PILES and PILES of pumps that according to their published spec data would work...but then when you test them in a real life application fail miserable. Finding a good reliable boost pump is the NO 1 Problem DIY-ers have in building their own water maker and where they waste the most amount of money during the "learning process" of having them fail.

For a 20GPH system you probably have a 1.6GPM Pump...that will need at MIMIMUM 2.0GPM being pushed into the Hp Pump through the dual prefilters...less than that....and Amigo....you have Problems.
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Old 15-04-2020, 13:48   #6
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Re: Boost Pump Recommendation please (Watermaker)

Quote:
Originally Posted by SV THIRD DAY View Post
Hi Peter.
If you can mount the boost pump totally below the water line then you can use a centrifugal non-self priming pump and I would recommend Jabsco Part No: 50850-0012

However most cruisers can't mount the boost pump below the water line, so in that case I would recommend what we use as our standard 12v Boost pump for a 20GPH water maker which is Jabsco Part No:42755-0092

For the self-priming pump, we have added a 12v cooling fan to the motor which reduces the operating temp by 50-degsF. A cooler 12v motor is a happier and longer lived 12v motor.

Cheers
Thanks so much Rich. I am pretty sure I can keep this pump beneath waterline, next to my AC pump. This is super helpful.

Peter
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Old 15-04-2020, 13:49   #7
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Re: Boost Pump Recommendation please (Watermaker)

Quote:
Originally Posted by gpeacock View Post
A boost pump for a watermaker requires high flow, low pressure. These are surprisingly hard to find.
The Jabsco Third day mentioned is one option
A Johnson CM30 is similar.
Both are pretty expensive and the Johnson is hard to find in the US.

When my Johnson CM30 died on my 20GPH engine driven watermaker I tried a CM10 (lower flow rate) and there wasn't enough flow to keep the low pressure switch happy. After trying a bunch of other pumps I ended up going with a much cheaper Bosch Automotive 0392022010 which can be found anywhere.
It's flow rate is less than the CM30 at higher pressures but it works fine to keep the Pressure pump flooded even when my two pre filters are nearing the end of their life.

All the pumps I mentioned are not self priming but as Third Day mentioned keeping a self priming pump that works with the flow requirements of a watermaker probably necessitates a fan so it doesn't burn out. Find a way to install your pre pump below the waterline.

I have since started using the Bosch in my Hydronic heater circuit as well. Both have been very reliable despite long continuous run times with hot and corrosive fluids.
Whoops... I got the part numbers mixed up.
The original system spec'd a Johnson CM90 which is similar to the Jabsco 50840-0012. Both pumps run in the $300-400 range and flow around 25-30 GPM.
The Johnson CM30 while cheaper mostly worked but couldn't push enough water through the filters when they were getting clogged. Its rated at 5-6 GPM.
Thats when I switched to the Bosch 0392022010 which is also rated at 5-6 GPM but has a better push at higher pressures than the CM30. I've had no problems since.
If you don't have a low pressure switch in your system don't skimp on the pre pump. Even the most expensive Jabsco is still cheaper than a rebuild alone on your pressure pump.
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Old 21-04-2020, 22:45   #8
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Re: Boost Pump Recommendation please (Watermaker)

I'm installing a watermaker now and it came with an Everflow EF3000 which is available in the US, 3.0GPM open flow.

On another issue, am I correct in assuming that the Pushfit style fittings cant be used below the waterline?Click image for larger version

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Old 22-04-2020, 06:54   #9
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Re: Boost Pump Recommendation please (Watermaker)

Magnetic clutch pumps last longest

They are not self priming so must be mounted below waterlines

No axle shaft seals , I’ve seen them run for twenty years

https://www.marchpump.com/applicatio...-conditioning/

The most common on yachts are from March
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