Comet Pressure Equaliser / Accumulator Failure

[duncansw]

On my Bavaria C37 (2006) it has a comet pressure equaliser after the pump and at the weekend it litterally exploded ... the damage shown below is very odd and I cannot see what would have caused it anyone had anything similar? next q is what does it actually do as I bypassed it as cannot see any difference - I have read about reducing pump use but I have never run a tap and the pump not come on plus the volume is very small? they do not seem expensive to replace so I will do that but would like to know what made this fail?

 

[dk]

It smoothes the flow, which is important if you have a shower. Stops the pump surging. That one looks naff though - I'd look for a better quality one this time!

 

[johnalison]

Vorsprung durch technik! Perhaps not everything from Germany is well made. It could be that there was a weakness in the tank, or that the tank was damaged by something like heat, or improbably that the pressure was too high. I'm not sure what you mean by saying that you have never run a tap - is there any other way of getting water? It may be that the system will work with the tank bypassed, but this may cause the pump to cycle on and off, which is irritating and may potentially harm the pump. The pump will have a pressure switch rated for a certain range of pressures which will be marked on it. Providing the pressure is not excessive to to failure of the switch, there is no harm in bypassing the tank and seeing how it works. Replacement tanks are fairly widely stocked, moslty those from Jabsco.

 

[duncansw]

Vorsprung durch technik! Perhaps not everything from Germany is well made. It could be that there was a weakness in the tank, or that the tank was damaged by something like heat, or improbably that the pressure was too high. I'm not sure what you mean by saying that you have never run a tap - is there any other way of getting water? It may be that the system will work with the tank bypassed, but this may cause the pump to cycle on and off, which is irritating and may potentially harm the pump. The pump will have a pressure switch rated for a certain range of pressures which will be marked on it. Providing the pressure is not excessive to to failure of the switch, there is no harm in bypassing the tank and seeing how it works. Replacement tanks are fairly widely stocked, moslty those from Jabsco.

thanks - what I meant is that the pump always comes on when I run a tap - some forums suggest that these tanks mean you haver get some water without the pump kicking in

 

[jwilson]

On my Bavaria C37 (2006) it has a comet pressure equaliser after the pump and at the weekend it litterally exploded ... the damage shown below is very odd and I cannot see what would have caused it anyone had anything similar? next q is what does it actually do as I bypassed it as cannot see any difference - I have read about reducing pump use but I have never run a tap and the pump not come on plus the volume is very small? they do not seem expensive to replace so I will do that but would like to know what made this fail?

View attachment 120124

Looks like a moulded plastic tank - both my accumulator and expansion tanks are steel. Interesting it says 3 bar max - this is pretty close to normal pressures for some water pumps, and calorifier PRVs often get set to 3 bar.

 

[duncansw]

. It could be that there was a weakness in the tank, or that the tank was damaged by something like heat, or improbably that the pressure was too high. I'm not sure what you mean by saying that you have never run a tap - is there any other way of getting water?

I'm working on weakness + 15 years old as expect it was original - no chance of any heat where it was mounted and pressure of the pump is 30PSI / 2bar

 

[Oily Rag]

I would expect an accumulator to have air inside, either in a bag or trapped at a high point. And a means of topping that air up from time to time. If you always get the pump running when you turn on a tap, then perhaps there was no air in it. Without air to cushion any water hammer, you can get a fair pressure pulse when you close a valve quickly. It usually has no effect on small bore pipe because it can take fairly high pressures, but an old 3bar vessel would be the weakest link.

So....is there a valve to allow it to be recharged?

 

[johnalison]

thanks - what I meant is that the pump always comes on when I run a tap - some forums suggest that these tanks mean you haver get some water without the pump kicking in

Ah, I see. My system will produce a squirt of water if it is pressurised and the pump switched off. This can only be as much as the accumulator can provide, a few cupfuls perhaps. I usually run this off when leaving the boat so that it doesn’t stay pressurised, potentially limiting the life of the accumulator diaphragm.

 

[duncansw]

I would expect an accumulator to have air inside, either in a bag or trapped at a high point. And a means of topping that air up from time to time. If you always get the pump running when you turn on a tap, then perhaps there was no air in it. Without air to cushion any water hammer, you can get a fair pressure pulse when you close a valve quickly. It usually has no effect on small bore pipe because it can take fairly high pressures, but an old 3bar vessel would be the weakest link.

So....is there a valve to allow it to be recharged?

no it's a very basic device - basically a 1 plastic bottle - have just ordered a jabsco 2l one and that has a air value on top so hopefully that will be much better

 

[johnalison]

no it's a very basic device - basically a 1 plastic bottle - have just ordered a jabsco 2l one and that has a air value on top so hopefully that will be much better

Jabsco used to sell two versions, one with a diaphragm and one without. I had one without for a while, and although it worked for a while, the casing split at the tap, which was a ridiculously tight fit, and I changed to a diaphragm.