FW pump variable speed or constant speed with expansion tank.

[rslifkin]

I went for a 60 psi pump like Simi due to system needs, although not for the same reasons. I've got a pretty hefty set of filters in the system, and at higher flows they're enough to cause 10 - 15 psi of pressure drop. So having a pump where the cut-in pressure wasn't too low was important (current pump cuts back on around 40 psi), otherwise flow would get pretty weak when you got close to cut-in pressure.

 

[Ka_sea_ta]

I want to expand on this thread. Including the fresh water flush for the WM there are 11 FW fixtures on our boat and with a single flo jet variable speed pump with no accumulator, the water pressure and volume is anemic at best. I would like to design a system to improve the flow and also put a boost pump in for anchor washdown. This is an area where I don't have much experience so any ideas or help would be appreciated. Thanks

 

[tiltrider1]

I am not an expert on plumbing. Everything I have been told and experienced comes down to the GPM rating. Houses generally have a flow rate between 6 and 12 GPM. My Marco pump is rated at 9.5 GPM.

I find that I never need to turn full water on at any faucet for any reason. The down side to a high flow rate is conservation. Less of an issue if you have a water maker.

While I originally thought my Marco UP12 was over kill, I have come to really appreciate the luxury of having more water flow than I need.

I now plan to upgrade my wash down pump with a Marco UP12. This will give me a back up in an emergency.

 

[C lectric]

I made these changes likely 25- 30 yrs+ ago with changes as problems showed up.

All part of the same job. I installed a Groco 1 gal. accumulator which is still in operation.

THe original Jabsco diaphram pumps constantly croaked the on/off switch about every year or so.. I left the on/off micro switch in place as a port plug. Best use I could think of.

---I installed a Square D switch with an adjustable pressure setting. I used a diode to stop the flashback from the motor burning the switch. This lasted 20-25+ years.

-- When the first switch croaked I got a new one + a spare. Same diode setup for same reason.

-- The jabscos had to be rebuilt every year or two for about $100.00.

--I finally changed to a Jabsco 31395 pump with built in on/off which I bypassed in favour of the Square D pump switch.

I mounted the new pump vertically , pump motor on top, Works just fine for the last 2 yrs. Aside from the pump I expect this will last at least 15 + years.

Just what I did. If this Jabsco croaks I likely find a different one. THere are better ones out there such as Whale, Johnson and so on.

 

[Ka_sea_ta]

Here is my current line of thinking, to use a dual pump system with the pumps in parallel and an accumulator. This should be good for 8 to 10 GPM at 40 PSI.. Even with a pump failure I would be no worse off then I currently am with the existing system. This is an example of what I'm thinking.

For a washdown boost pump I would use the same model pump as is used with my watermaker as a boost pump.... are there other better solutions?

 

[catalinajack]

Here are two alternatives, either of which will solve all of the aforementioned inadequacies. Install a Grundfos pressure/volume booster pump (accumulator not needed), or a shallow well pump with an accumulator. The Grundfos product has a fixed pressure setting of 60 psi. Any shallow well pump will come with an adjustable pressure regulator. Both are pretty much bullet proof.

 

[tiltrider1]

Here is my current line of thinking, to use a dual pump system with the pumps in parallel and an accumulator. This should be good for 8 to 10 GPM at 40 PSI.. Even with a pump failure I would be no worse off then I currently am with the existing system. This is an example of what I'm thinking.

For a washdown boost pump I would use the same model pump as is used with my watermaker as a boost pump.... are there other better solutions?

Yes, that will work. I am not a fan of cheap diaphragm pumps. I find that they have a short working life. I feel there are better solutions but not at that price.