Fresh water accumulator

S

saltyrob

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Hi Folks,

The boat,1986 vintage /forums/images/graemlins/confused.gif, is fitted with a black 1L accumulator on the domestic fresh water supply. This is fitted with a screw cap on top which I understand can be used to occasional adjust the system. I am not sure how and why it needs attention so any advice would be gratefully recieved

Robert
 
Is the screw cap on the end of what could be described as a tyre valve?

If so, then you can adjust the smoothness of the water flow rate by either increasing or decreasing the air pressure inside the accumulator 'balloon'. Use a pump with a gauge to check the pressure inside.
 
Hi SR,

The accumulator is there to provide a air reservoir for the pressure system. This volume acts as a sort of 'cushion' for the pressure exerted by the pump, so that when you turn the tap off, the pump continues for a very short while pressurising the system and compressing the air in the accumultor until the preset pump pressure is reached.

Thus when you next turn the tap on, water will flow for a short while before the pump starts again to renew the pressure. It also reduces the number of times the pump has to cycle on and off when you draw off water for a longer period. The bigger versions with a diaphram are better because they have a larger volume, so that more water can be drawn off befor the pump cuts in.

After a while (varies with the amount of use) the air in the accumulator gets absorbed and it fills with water. Therefore no cushion. When this happens, perhaps once or twice a season, you simply have to switch off the pump, remove the plastic bung at the top of the accumulator, remove one of the hose connections at it's base, and drain it until it's empty.

Refit the bung and the hose and switch on the pump. Then bleed the system by opening the the tap furthest from the pump to remove any air, the the next nearest and so on. Once they're all air free, your finished!!
 
The accumulator stores some of the water as the pressure increases and returns some to the system as the pressure drops.

If your system has what appears to be a bicycle type air valve then the air pressure should only be set, with the pump turned off and one tap turned on (no pressure in the water system). The air pressure should be set to the water pumps low pressure setting.

The PAR pumps for leisure boating normally have settings of low 20 high 40 or low 10 high 20 lbs/sq” others may vary.
 
The small black accumulators dont have a diaphram, tey are mounted above the pipe and trap air which is compressed by the pump. You can tell if its working by turning a tap on and timing how long it takes for the pump to start. If the pump starts straight away then the accumulator is full of water and not doing its job.

Turn off the pump, disconnect the accumulator drain the water out and refit it. When you switch on the pump it will run for a a few seconds (with the taps turned off) as the air in accumulator is compressed.
 
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