Using non diaphragm pumps for fresh water system.

[Spikes]

I need to install a fresh water pump system in my Columbia 36. There is a foot pump for the sink which is a good backup but I really would prefer something electric. I have heard diaphragm pumps can be noisy, then you also would want a pressure switch and all of this adds up. So I was thinking about using centrifugal pumps, the type used for water fountains and recirculation. I won't have a pressure switch as these pumps are low pressure. My idea is basically to install 2 centrifugal hot water pumps for the shower ( one for hot and one for cold) and then probably just one for the sink. Instead of using a pressure switch that activates my pump when the pressure is relieved in the system I'll just have a switch on the wall to turn on my pump, one in the shower to turn on the hot and cold pumps and one at the sink to turn on the cold pump. I can pick these pumps up for around $20 a pop and they use very little current. I am also looking at water transfer pumps or water pressure booster pumps those are also non diaphragm. I don't understand why it seems like you "have" to use diaphragm pumps for fresh water systems. I believe the workaround is just to have a power switch at the faucet location. Anyhow this is what I plan to do. Less expensive and less chance of my system leaking from being under constant pressure. What do y'all think of this, is there any reason I have to use diaphragm pumps?

Water fountains don't and they seem to spray water just fine enough for what would be decent enough for a shower. For anyone curious about how this would work out we just need to convert this type of pumps head rating to psi. https://www.convertunits.com/from/foot+of+head/to/psi

A decent centrifugal pump should deliver 10-20 psi, they make shower heads for use in low pressure systems.

[Bowdrie]

It's workable, the pump(s) needs to be below the tank, so the inlet is flooded.
Each time you turn the switch off the lines will drain back unless there is a check valve.
Many of them would not like to pump hot water, so if you desire a separate pump for hot water, you need the pump on the cold-water inlet side of the heater.
You do NOT want the water heater to drain back, it must stay full.
Here's a Johnson pump:
https://www.fisheriessupply.com/john...culation-pumps
Groco also has good products, (for ~twice the cost).

[Cheechako]

I thought about it. In some ways it's more complicated than just a diaphragm pressure pump. The common diaphragm pumps come with their own pressure switches BTW. No separate pumps etc. You just pressurize the system and route it through the water heater as well. One pump. Yes diaphragm pumps fail. Once you get a good one it can last for years though.
There are other options including the old school rubber bellows type, but they are abusively expensive for what they are.
Or the big bronze water system pumps, centrifugal I think, those are great, but very expensive now days.
You are talking about a lot of switches and complication to do a job that is simple with a normal water pressure pump.

I suppose using a circulation pump (centrifugal pump) as shown above could be worked out fine. Centrifugal pumps can run with faucets closed, so one pump, one switch could be used. Need water? Turn one switch on, use water at the sink or shower as necessary. Route that flow to the water heater also, and you may need a check valve so the water heater doesn't drain when not in use. When not using, turn the switch off.

[Bowdrie]

Originally Posted by Cheechako

Or the big bronze water system pumps, centrifugal I think, those are great, but very expensive now days.

Yes, Groco makes a bronze centrifugal pump that costs several hundreds of dollars.
They also make a positive displacement pump that would give you a heart attack.
I installed one of these several years ago for a customer, a fantastic device, but not for the faint of heart.
https://www.oceanlinkinc.com/product...12vdc-psr-12v/

[Spikes]

I don't have a water heater yet but I was thinking either a propane instant hot or I was thinking of getting a 55 gallon drum and wrapping it with some type of insulation and then buying some of those pool solar heater mats and maybe building a couple shallow boxes to put them in with some type of clear cover, acrylic , plexi or the cheaper route and something like a clear vinyl tablecloth stretched tight of course. Then I would use a solar hot water heater recirculation pump to get my 55 gallon drum up to temp. I wonder how well this could work? I found pool solar heaters for under $100 could be mounted on deck or mounted on a solid Bimini.

Ps. If I put the drum on top of the cabin strapped to the mast I would have the added benefit of gravity helping my water flow to the shower / sink