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easttnboater
08-14-2013, 06:45 AM
I run my boat exclusively off of the fresh water tanks (360 gallons). I am looking at replacing the 12v pump with a 120v shallow well pump to give me more volume and more consistent pressure. I have plenty of 120v capacity.

Has anyone else done this?

Stmbtwle
08-14-2013, 09:10 AM
You'll also have to install a pressure tank to go with the pump, but my guess space and weight is not an issue so it should work. A shallow well pump works with a pressure switch just like your 12v pump, so you'll still have pressure variations though depending on the switch and size of the tank they MIGHT not be as noticeable.

In my experience the size of the tank has more bearing on volume delivered over a short time than the size of the pump. With a large pressure tank you can use a fair amount of water pretty quickly before you notice any difference in pressure or the pump even comes on. Once you stop, even a small pump can catch up. Of course if you have a lot of people all taking showers at the same time you may actually need the pump capacity.

I'd install the larger pressure tank FIRST (you'll need it anyway)... and wait and see if I really needed the shallow-well pump. You can also experiment with adjusting the pressure switch on the pump you have.

easttnboater
08-14-2013, 09:38 AM
I have one of the small pressure tanks now - about the size of a kid's football. My biggest problem is volume - especially when more than one outlet is being used. I was thinking along the lines of something like this:

http://www.northerntool.com/shop/tools/product_200352050_200352050?cm_mmc=Google-pla-_-Water%20Pumps-_-Shallow%20Well%20Pumps-_-109231&ci_src=17588969&ci_sku=109231&gclid=CMXzo6Gi_bgCFcuf4AodBxwAjg

Stmbtwle
08-14-2013, 11:34 AM
My pressure tank is 2 or 2-1/2 gallons, it's actually an "expansion" tank for a domestic water heater and quite a bit bigger than a football. For normal handwashing, dishwashing etc it's more than enough for us even with the 3gpm 12v pump. For showering though the pump IS maxed out.

However I imagine you have a lot more people using a lot more water than we do so the pump you're looking at might work pretty well. I have no issues with 120v as long as you have the power available. I think I'd leave the 12v pump hooked up though; in case your genset goes down. Maybe add a check valve.

easttnboater
08-14-2013, 01:08 PM
I have redundant 12v pumps now. I would definitely leave one of them in place as a backup. I am also thinking about replumbing the boat using PEX and a manifold - basically making separate, individual runs to each outlet. Got to have a winter project.

JTAlberts
08-14-2013, 01:46 PM
I have redundant 12v pumps now. I would definitely leave one of them in place as a backup. I am also thinking about replumbing the boat using PEX and a manifold - basically making separate, individual runs to each outlet. Got to have a winter project.

That is on my list as well East. I am going the Pex route as all my water pipe is old and cracked.

easttnboater
08-15-2013, 11:52 AM
My CPVC pipe itself is in OK shape. The problem is the the whole boat is plumbed in 1/2 OD pipe with very few cutoffs. So I have a volume problem and I cannot isolate pieces of the plumbing to work on it. I like the idea of a manifold and individual runs to each outlet.