Fresh water pump - flow rates

[Insequent]

I am looking to replace my fresh water pump in the near future. I have two heads/showers, a galley sink and icemaker as the users. My current pump is 10 GPM and 67 psi max. I'm not sure that I really need that flowrate as have never needed to run both showers at once.

What kind of flow rates do you find to be the minimum, or desirable, for that kind of system?

Does any one use an AC powered pump, or are the 12/24V 'marine' DC pumps the better option anyway?

 

[Lepke]

I use a shallow well AC pump. They pump more water and last longer than DC pumps and motors. My current pump came with the boat and I'd guess it's 20-30 years old. It's rated at 9gpm. When away from the dock it runs off the inverter. I do have a spare pump/motor.

The way my boat is setup, all AC power runs thru the inverter. If a generator is on or I have shore power, the inverter becomes a charger. There's no loss of power in switching. I don't run a generator when the mains are running. I have alternators that keep the batteries up.

 

[boathealer]

We have given up on "marine" pumps at 2-3x the cost with no additional performance or longevity over many others. We bought an RV pump (link below) and have been using it constantly as liveaboards for over two years. It has been flawless. It is 3gpm/40PSI and is fine for us with 1 shower/head, galley, freshwater head, and cockpit shower.

https://www.amazon.com/gp/product/B00K8D9IN4

It appears that our 40PSI model above is discontinued, but there are links to an equivalent 60PSI model on that same page.

What I really like about this pump is that the entire mounting base is heavy, solid rubber. This makes it very quiet when running.

Since the cost was so low, we bought a second pump as a backup for when (not if) it died. We also made the electrical and plumbing connections a "quick disconnect" for just this case - kind of a "hot swap". BUT.......we have not needed any of it as yet!

 

[rslifkin]

My pump is only rated for 3 gpm (and 40 psi cutoff), and with realistic system pressure, it's probably only pushing somewhere around 2 - 2.5 gpm, depending on if one or more taps are open. I've never found the flow inadequate. And I can't see a reason to want more unless using multiple taps at the same time were a frequent occurrence. A bigger pump just makes it easier to waste water.

 

[FF]

The DC pumps seem fine for the seasonal cruisers , tho may have a shorter life if used for liveaboards.

A couple of tricks can extend their life a great deal..

#1 is to install an accumulator at least a gallon with more being better, br sure its got the proper air pressure.

#2 Most pump heads are the same in the same brand , the difference is the motor.

The largest motor seems to last the longest so purchase a bait well or wash down pump , with the biggest (longest) motor.

The pressure control for DC eats the points a bit every time the open .Simplest and best cure is a second house well pump pressure controller from a box store be sure to get one that has a low pressure cut off , so if the tank runs dry the pump will shut off.

You can reset the pressure cut off to lower than the DC pump would use , so any wear is on the $19.00 home well pump control.

Set the pressure as low as it is comfortable in daily use.

 

[rslifkin]

Another fix for pressure switch lifespan on the DC pumps is to have the pressure switch drive a relay that powers the pump motor. Then the small pressure switch contacts are only taking the relay coil load, which is small. And the easily replaced (cheap) relay takes the big load.

My fresh water pump isn't done this way, as it's in the engine room and needs to be ignition protected. But my washdown pump (in the forward bilge) is, as it's got a huge motor and draws a bit over 25 amps, so most small pressure switches would have a very short life.

 

[catalinajack]

I have a Grundfos MQ3-35 3/4HP 110VAC pump that is rated at 13 GPM and does not require an accumulator. It starts on demand and provides steady pressure and never-ending volume. The Grundfos MQ is a compact, all-in-one, flow based, plug-and-play pressure boosting system, designed for domestic water supply applications such as homes, cabins, cottages, farms as well as gardens. The pump is suitable for pumping of potable water and rain water. In truth, it is overkill for a boat but, once purchased and installed, it will far outlast the life of the boat.

A shallow well pump works in much the same way but it needs an accumulator and has cut-in and cut-out set points. The Grundfos comes on and stays on when a faucet or shower valve is opened and provides steady pressure, NO surging. However, the Grundfos is large, slightly larger than a shallow well pump, but taken together with an accumulator takes up more space than a Grundfos.

The downside to the Grundfos is cost about $575. I just checked prices. But, if you have the space, the Grundfos will be a one-time purchase and never mind the peace of mind of reliability - think about what it is designed for - and, as I said, NO on-off pulsating and gobs of volume. By now now it is obvious I am a fan.

The Grundfos plugs into a standard 110VAC receptacle.

https://us.grundfos.com/products/find-product/mq.html

 

[catalinajack]

Wasting water is wholly a function of the user. I just posted about my experience with a Grundfos pump. No need to worry about someone opening a tap while someone else is taking a shower. Sure, one can "get along" with just about anything but at this point in our lives, why would anyone want to do that excepting financial limitations?

My pump is only rated for 3 gpm (and 40 psi cutoff), and with realistic system pressure, it's probably only pushing somewhere around 2 - 2.5 gpm, depending on if one or more taps are open. I've never found the flow inadequate. And I can't see a reason to want more unless using multiple taps at the same time were a frequent occurrence. A bigger pump just makes it easier to waste water.

 

[MYTraveler]

Since you asked, my boat has 12v and 120v pumps wired in parallel. I generally keep the 120v turned off, except when we have a bunch of people on board.

 

[Lepke]

I use 2 switches on my shallow well pump. On is the traditional w/high & low settings. The other turns on the pump as soon as a faucet is opened, maintaining pressure. A relay controlled by a switch in the galley makes the switch. When I'm on the boat by myself I usually use the stock switch unless there's a lot going on, washer, shower, etc.
The continuous pressure switch is under $50 on ebay.

 

[O C Diver]

I switched to a 5 GPM 60 PSI 12 VDC washdown pump, with home well pressure switch and about 4 gallon bladder pressure tank. IMO, the pump should last longer with fewer cycles. Have the switch set at 40 PSI on, 50 off. I thought about going with a 120 VAC pump, but would have had to change plumbing size to handle increased flow (suction side).

Ted

 

[Simi 60]

We have used the Vetus 13 lpm 24v pump at under $150 and it was more than adequate but the smoke came out of it after 2 years of full time use.

Vetus have a 3 year warranty so they suggested the more robust 22 lpm model and replaced it and the spare that we carry with that model and no extra coin changed hands.
Easy access, 5 minute changeover
Its been in a bit over 2 years now.

Oh, and we have a 8 litre accumulator tank bought from an irrigation shop online.


IF we had 240v ready to go in that location I would have one of these
40lpm with built in accumulator

mtfwater.com.au buy direct Water Pressure Pumps, Submersible Pumps Filters and Pump Accessories

A mate has been using one full time for about 10 years
$145 and Brisbane seller

 

[Insequent]

We have used the Vetus 13 lpm 24v pump at under $150 and it was more than adequate but the smoke came out of it after 2 years of full time use.

Vetus have a 3 year warranty so they suggested the more robust 22 lpm model and replaced it and the spare that we carry with that model and no extra coin changed hands.
Easy access, 5 minute changeover
Its been in a bit over 2 years now.

Oh, and we have a 8 litre accumulator tank bought from an irrigation shop online.


IF we had 240v ready to go in that location I would have one of these
40lpm with built in accumulator

mtfwater.com.au buy direct Water Pressure Pumps, Submersible Pumps Filters and Pump Accessories

A mate has been using one full time for about 10 years
$145 and Brisbane seller

I have ordered a 12V Vetus, the WP1220. Its 20 lpm, I don't see any 22 lpm models.

If I had AC at the pump location an MTF unit would have been a better option for sure.

Meanwhile, I have used the 'Contact Us' link for Headhunter. I have an X-Caliber XR124. It has two impellers, but the hub broke away from the body on the front one as shown in the pic. They have Mach 5 kits on their webpage, but nothing on spares for the X-Caliber. However, the impellers look similar. Hopefully I can get a replacement impeller, and then the Vetus can become a spare.

 

[FF]

If the FW system is being replaced 5/8 copper tubing will allow good volume with lower line pressures .

Some also prefer the copper to plastic tubing as boat FW may sit for long times.

 

[Simi 60]

.

Meanwhile, I have used the 'Contact Us' link for Headhunter. I have an X-Caliber XR124.

$1600
Seems an insane amount of money for something as simple as a pump

https://www.amazon.com/HEADHUNTER-X-caliber-Water-Pressure-Pump/dp/B0027YQNQW

Raw water pump for the 855 Cummins was half that and its 10kg of bronze and S/S

 

[Insequent]

If the FW system is being replaced 5/8 copper tubing will allow good volume with lower line pressures .

Some also prefer the copper to plastic tubing as boat FW may sit for long times.

Potable water lines were replaced with PEX 8 years ago. I'm very happy with it.

 

[Insequent]

$1600
Seems an insane amount of money for something as simple as a pump

https://www.amazon.com/HEADHUNTER-X-caliber-Water-Pressure-Pump/dp/B0027YQNQW

Raw water pump for the 855 Cummins was half that and its 10kg of bronze and S/S

Well the PO installed it, likely around 15 years ago. He replaced a Paragon Senior, which probably cost 50% more than that, but left the Paragon on board. Other pump threads say that Paragon service kits can get them running fine again. But so far I've not found anyone here to do it, although there could be someone in Coomera. But its likely to be many hundreds for the kit and installation so its not a priority.

I was a bit surprised to find plastic impellers in a pump as pricey as the Headhunter.