Water temp pulsing warm cold.

[michaf]

I've got a Quick water heater setup and I can't get the water temp stable, bit annoying when we take showers. There's a mixing valve in the setup but it doesn't seem to make a difference, I think it just sets the max temp of the hot water out. I've noticed that the pulsing comes from the pressure in the system as the pumps repressurise. Logically the problem would be that the cold and hot system don't repressurise exactly in sync. I must say I haven't tried to understand the whole pressure system... Any idea appreciated!

 

[jrudge]

You don’t say what Boat etc.

I had this on a targa 40. Boats.co.uk replaced the pump which fixed it. You should also have a pressure vessel near the pumps which is designed to smooth the flow. They can need pumping up - a bike pump works.

 

[michaf]

Thanks, I understand better now. Will try tp pump the accumulator, we'll see if it makes any difference.

 

[BartW]

in our boat, the water supply pump is in the engine room, and the water boiler is at the other end of the boat, (in the bow)
the water supply to the boiler is at the end of a long water supply hose, with inbetween many outlets to the cabins.
so when one of the showers in the cabins was used, the cold water pressure at the input of the boiler was dropping until the pump started, ... this caused our showers water temp to fluctuate too much.

we installed a separate water supply hose from the pump (through the bilges) to the boiler input.
this cured the problem almost completely.

another problem we have:
the shower on the swim platform has a on-off valve on the shower head,
there is a warm / cold / open close mixing valve in the shower locker,
guests tend to leave that mixing valve in the "open" position, and just close the valve on the showerhead when they have finished using it,
but then cold water tends to go in to the hot water hose via the mixing valve,
as the cold water supply is much closer to the pump (ER) than the hot water (Bow), there is less pressure in hot than the cold water supply. (causing water temp fluctuations in the cabins....)
I've recently installed a shower handle without a valve, so that users are obliged to "close' the mixing valve

I hope its clear what I wrote above

 

[michaf]

Well I got the accumulator back to 18 PSI but made no difference. We're just going to live with it I guess. Our boat is a Velasco 43.