Shower pulsing

Hi,

I don't have actual experience with you size boat but I will try to give you a few ideas where your problems might be.

Your fresh water system should have a small captive air tank in the line from the pump to the pressure side of the system. This holds a quanity of air either in a rubber bladder or directly in contact with the water, it is designed and installed to stop pressure surges in the system caused by the start and stop of your pump and to take care of minimal on and off of the taps. ( A Glass of water etc).

Your pulsing is caused by the pressure dropping and the water flow decreasing and as the pump kicks in and the pump outlet pressure increases so does the flow till it reaches it's cut out pressure and the whole cycle starts again.

When you have the Valve in the hot position I would say from your description of reduced flow ( less run time from more pump starts)that there is some type of restriction in your hot water heating system that is causing the flow to be less and it takes longer for the system to reach a pump start point and it recovers quicker purely because there has been less water moved between the points.

What system do you have for heating your hot water?

If the boat has been somewhere with very hard water you might find the H.W System is full of lime scale and crud.

I am not sure if your type of boat has a ring main for the hot water, this if fitted will need a circulation pump just like you have in the water side of the central heating system in your home. If it is done it's day that can also cause flow restrictions.

I hope I have not confused you with my writings.

Please post back as you go when you find the problem and the solution.

Hi,

I have gone past the editing time to add this above having thrown out the garbage and traveled to work including a ferry ride and a stop for some lunch fixings since posting that.

Here is a simple schematic of what the author sees as a typical Fresh Water System, there is an accompanying glossary of the terms and a system description which might help you nut out what the situation is with your system.

http://www.boatus.com/boattech/casey/16.htm

Does the same thing happen when you turn on the sink faucet?
If it does not, then the problem is in the shower valve.
The acumulater is probably flooded also. When the bladder fails it looses pressure and the system pump will cycle on and off rapidly.
If you end up looking to upgrade the system- variable speed pumps use less power, are much quieter and can run with or without an acumulator. They may be called smart pumps but they start up slowly and only run as fast as needed to maintain pressure.
Have fun.