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Old 12-25-2012, 10:52 AM   #21
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The primary reason for a tank is soften the water pressure, In dirt houses the tubinh is runner higher creating a air cushion so when the water is turned off the is no sudden pressure banging of the pipes. So it protects the boats water system.

If will also reduce the number of times the pump comes on.
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Old 12-25-2012, 11:18 AM   #22
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depends on the type of pump you use. mpst are vane pumps, so a small acumulator tank is what you need.
As for pressure, I recently had a problem with one, so got into this conversation with a plumbing supply shop, who advised "17 psi" is what should be on the pressure side of the accumulator. It has a schraeder style bicycle tube valve, so put your pressure guage on it, and charge if it is low. The only presumption here is that your system is to run between 40psi and 60 psi at the pump, where there will be limit switches.
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Old 12-25-2012, 12:09 PM   #23
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Originally Posted by RickB View Post
Bigger the better. There is a reason they build these things ....
Not the same principle as an accumulator tank. The accumulator is designed to take the shock or hammer out of lines and to a certain extent smooth out the flow. The big utility water tanks are designed to add to supply when the pumps can't keep up. The water released is gravity flow, so smoother than pumps cutting on and off. They are vented so that the water when released will not "gurgle" as it is released. and when the tank is filled that air will not be trapped reducing capacity. You can indeed put minnie accumulators at each fixture by simply installing a riser above the "T" that feeds the fixture. This traps air and provides the cushion. You can drain a water logged riser by simply draining the system to trap air in the riser again.
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Old 12-25-2012, 12:45 PM   #24
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Only the style of tank with an internal diaphram is worth installing.

The RV and cheapo units have an air chamber (if installed properly) that is in contact with the FW.

Eventually the water carries off the air and the "accumulator " does nothing.

This can be noticed by the no time at all between the faucet opening and pump operation.Drain the unit and reconnect to get air in, for a while.
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Old 12-25-2012, 12:48 PM   #25
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The tank I installed is intended to supply a relatively steady water pressure and reduce the number of times the pump runs. Without the tank, the pump must run whenever water is drawn from the system, no matter how low the flow. It's the same system used in homes and small commercial buildings serviced by a private well, but on a smaller scale.

It is not intended to reduce or eliminate "water hammer" from shutting off faucets. It is possible, as Moonstruck states to do this with a riser on each line at each outlet although I doubt anyone would have this problem on a small boat with low water pressure.

In theory, bigger is better as someone mentioned, but any boat is a compromise. The one I installed has a capacity of just over a quart and does what I need it to on my boat, keeps the pump from running or chattering if I run a half cup of water to wash my hands or brush my teeth. Taking a shower or washing dishes, the pump will run continuously and that's fine.

The tank's air pressure is factory set at 10 PSI and that's fine for most marine applications. It should never need to be refilled with air or adjusted differently on most boat systems.

This is the one I used:

http://www.amazon.com/Jabsco-30573-0.../dp/B000O8D5XM

Here are the installation instructions including an explanation of how it works:

http://www.velasalan.is/modules/list...8041_880_1.pdf
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Old 12-25-2012, 01:49 PM   #26
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It is not intended to reduce or eliminate "water hammer" from shutting off faucets. It is possible, as Moonstruck states to do this with a riser on each line at each outlet although I doubt anyone would have this problem on a small boat with low water pressure.
It most certainly will absorb shock out of lines. This is most noticeable on larger boats that may have appliances with solenoid shut offs such as washing machines. Anything that reduces shock and stress can prolong the life of lines (especially PVC) and "O" rings.
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Old 12-27-2012, 09:59 PM   #27
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You will probably want to check if it is holding pressure.... When I put in a new pump a while ago...I went to check the pressure and I found that the air bladder in the accumulator tank have popped...whole thing was full of water and not functional.

I ended up using a VSD pump....works quite well and has no need for an accumulator tank.
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Old 12-27-2012, 10:17 PM   #28
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Our system uses a Shureflow three-chamber diaphragm pump with a small Shureflow accumulator tank next to it. The accumulator tank is less than a foot long. According to the manual for the tank which came with the boat, the tank has only one purpose and that is to eliminate hammering and pulsing in the lines when the pump comes on. When we open a tap the water flows immediately and a few seconds after it starts the pump comes on. Once it comes on it stays on until we shut the tap, after which the pump runs for a couple more seconds and stops. But there is no pulsing or hammering in the system.

If we can sort out our mystery problem with the pump we'll retain this system. If not and we decide to replace the pump we will install a variable speed pump as JAT has done and eliminate the need for the accumulator tank.
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Old 12-28-2012, 06:38 AM   #29
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I hate to burst anyone's bubble but the sketch showing a city water tower has absolutely nothing to do with a pressurized boat water system. The water tower uses gravity to provide pressure and there is no pressurized accumulator tank in that system. Apples and Oranges.
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Old 12-28-2012, 07:16 AM   #30
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The water tower uses gravity to provide pressure and there is no pressurized accumulator tank in that system.
The water tower uses gravity to provide a static pressure head on the water main.

A "volume tank" uses compressed air to provide exactly the same thing that gravity and tank volume does in the city water tank and that is to provide surge capacity and reduce pressure variations resulting from pump operation.

Nice try though.
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Old 12-28-2012, 07:29 AM   #31
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Unless you have a water tank hanging up high on your mast then the water tower has nothing to do with a boats water system. Duh.
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Old 12-28-2012, 07:33 AM   #32
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Valhalla, meet Somesailor, Somesailor, meet Valhalla.

Did they put something besides brandy in the eggnog this year?
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Old 12-28-2012, 07:38 AM   #33
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There's no fix'in ???????
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Old 12-28-2012, 09:50 AM   #34
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One fellow we know with a GB42 woody replaced a Shureflow pump/accumulator setup identical to ours with a demand regulated pump (don't recall the brand) and his only complaint was that because the pump was virtually silent in operation he couldn't tell if it was working. The fact water came out of the taps should have been a clue, I would have thought.
I actually like to hear if the water pump is running.
The reasons are simple.

If I hear the pump cycling then I know that water is being used. It could be caused by a legitimate use, or it could be caused by someone inadvertantly leaving a tap on, or it could be caused by a leak.

Also when I hear the pump run and not ever stop, thats a good clue to switch water tanks, although I try to not let us get to that point.


I lost a whole tank of water on one of my old boats once due to someone leaving a tap on. No watermaker, and 60 miles from port for a nice weekend.
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Old 12-28-2012, 12:13 PM   #35
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I also like to be able to hear the pump running especially with dirt company on board as they tend to waste a lot of water, which is limited on a boat. The tank is more important for those that connected to dirt domestic water which has a constant PSI to prevent sudden pressure when water is turn off. As mentioned be for most dirt domestic houses have air cushions built into the water lines. For this reason and encase a water line leaks/breaks I do not connect to the dirt/land water supply, but fill the tanks and run the pump. I still to not understand why dirt boaters think the boat has to be quiet, as most dirt homes are very noisy.
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Old 12-28-2012, 03:40 PM   #36
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Utility high rise water tanks as was illustrated do not use air pressure. They are all about water pressure. Pumping against air pressure would just be unnecessary work for the pump. If they used air pressure there would be no need for elevation. Water tanks and towers will be a the highest elevation, or they will be tall enough to provided minimum pressure to all served.
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Old 12-28-2012, 04:04 PM   #37
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Can you guys not start an argument about every damn topic on this forum? PLEASE?!?!? Can we not just politely discuss the topics at hand without going back and forth like a never ending tennis match? I'll give you a dollar.
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Old 12-28-2012, 04:09 PM   #38
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If they used air pressure there would be no need for elevation.

BINGO! Give the man a dollar!
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Old 12-28-2012, 04:44 PM   #39
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I actually like to hear if the water pump is running.
The reasons are simple.
I agree with this, actually. We don't mind the sound of our pump at all. To us, it's just a "sound of boating."

Our reason for getting a variable speed pump (if we replace our current pump) are to simplify the system and reduce the noise to a degree. This would benefit anyone using the forward cabin since the pump is right the other side of the bulkhead. But we'd still like to be able to hear it run for the reasons you describe.
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Old 12-28-2012, 08:59 PM   #40
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BINGO! Give the man a dollar!
Looking up a simplified illustration of "how things work" on the internet, is not the same as really working with things.

I know nothing about MTUs. The difference is I admit it.
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