Water pump GPM, is it worth uping the GPM?? - Page 2 - SailNet Community
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post #11 of 16 Old 05-19-2009 Thread Starter
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Just answered my own question:
"Extreme™ Series Smart Sensor Water Pumps
Designed specifically for cruisers, midsize and larger yachts, these pumps incorporate a special sensor that precisely monitors your system’s water pressure and adjusts the motor’s speed, eliminating the need for a pressure switch and accumulator tank"
Chip
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post #12 of 16 Old 05-19-2009
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Originally Posted by SanDiegoChip View Post
If we installed the Shurflo 5.7 Extreme 65 psi Variable Speed Pump Controlled by Smart Sensor would you think we could eliminate the pressure tank?
I am not familiar with that particular pump, but it sounds as if it is regulated by a pressure sensor and will produce up to 65psi of system pressure, which is a healthy pressure for a boat. I design municipal water supply systems where acceptable water pressures normally vary from a low of around 45 psi up to around 100psi.

I strongly suspect that you could install this or almost any other pressure regulated pump and then eliminate the pressure tank..... but why would you want to do this?

Unless you need the space, a pressure tank is a low maintenance fixture that balances out pumping demands. Remember that a dripping tap will very quickly lead to a pressure drop in any small water system not fitted with a pressure tank. Unless everyone on board is a very heavy sleeper, you could then be woken several times in the night by the pump switching on to boost the pressure drop caused by the tap drip! With a pressure tank, even running a tap might not cause the pump to start because this tank is then maintaining system pressures.

If you do decide to remove the pressure tank, please send it my way and I will fit it on my boat!
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post #13 of 16 Old 05-19-2009
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Neil is right, the pressure tank just reduces the number of times the pump runs. It is better for a pump to run longer, with fewer starts. A pressure tank also evens out the difference in pressure you get from the on and off settings. FWIW, I have bought and run at least 100 Shurflo Blaster pumps over the years in street sweeping equipment for dust control. They run all day in the worst conditions you can imagine (thick dust, extreme vibration, heat, dirty water, etc) and frequently run dry for hours (when someone forgets to shut it off). They are extremely reliable and last for several hundred hours of continuous running (which is not recommended by Shurflo). As far as I can tell, the Blaster (which is labelled as a wash down pump) is exactly the same as their water system pump, just cheaper. Cost is not a factor in why we use them, we have used much more expensive pumps but these have really worked well. Obviously I have had them in the boats for years too and have yet to replace one. Not connected to Shurflo, etc, etc., just very impressed with them.

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post #14 of 16 Old 05-20-2009 Thread Starter
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OK the pressure tank is not a space saving issue, although any added space would be good I guess. I was thinking it was one less thing to manage. I have no idea how long it has been in the boat. We bought the boat a few months ago from the original owner. 1978 Islander Freeport B. Any way he is 89 and does not remember a lot about the boat.
It does seem like a good idea to go ahead and keep it so as the water system runs smoothly.
Although we would want to bypass it for the shower because it will restrict the water flow.
So we will keep it at least for now.
On a side not we checked the hot water heater and it has written on it 127 psi \ 330 psi .

Thanks for the input.

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post #15 of 16 Old 05-20-2009
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Good Solution

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Originally Posted by SanDiegoChip View Post
It does seem like a good idea to go ahead and keep it so as the water system runs smoothly. Although we would want to bypass it for the shower because it will restrict the water flow.
The pressure tank will have an internal membrane that separates the water and air portions of the tank. About the only things that can go wrong are that the membrane can break, which is not a disaster and will not cause a leak but the tank will stop "balancing" or the whole tank could theoretically break or leak - which is a bit more traumatic. Unless you see signs of significant tank corrosion, it will probably work away without any maintenance for many years.

I strongly suspect that the pressure tank is fed from a "T" on the water supply pipe -although it could theoretically be installed "on line". If my suspicions are correct, you will not need to do any piping modifications to obtain the benefit of boosting the shower supply pressure with a more powerful variable speed pump.
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post #16 of 16 Old 05-20-2009
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Chip,

yes, remove your pressure tank and go for Variable Pump Motor. This was a great improvement to our system (amazingly lower noise and beter shower hot/cold mix as this don't pulse). Although many here stated correctly an upgrade on flow will not damage your system (they are ALL set to around 40psi) I wouldn't upgrade the flow unless you can't find a variable speed pump at 2.8 gpm. First, it will definitely suck more water when doing simple things like washing hands, cleaning and showering (I simply can't fine tune my hands to just open a little when I'm rushing in a sink) and second due to far more DC load posed to your batteries. Stay low, and you'll be happy.

Nave Rara
Beneteau Oceanis 43
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