Hot Water Temperature Stabalization.

[dougg]

The hot water stabilization has all gone to pot on our Jeanneau 42.

It used to be the case that we got a nice even temperature of water when showering.

However the temperature now fluctuates as the pump kicks in and out, ie when the pump cuts out the temperature of the water is to hot to stand under, then, when the pump cuts in again, the temp is fine for the next few seconds until the pump stops and so on.

As the pump feeds the cold water system and in turn the cold feed to the hot water cylinder, surely this will be balanced pressure hot and cold??

 

[vyv_cox]

One cause can be that the mixer in the shower head is partly blocked by calcium salts. A similar thing happens in our motorhome.

 

[Spi D]

Not knowing your setup advice is a bit hard.

I have a system that has one pump and accumulator tank that feed hot and cold circuits in common. The flow changes slightly when the pump kicks in, but hot and cold are equally affected.

Can you incorporate a tempering valve somehow?

 

[David2452]

A problem I come across not infrequently, you do not say whether you have a thermostatic shower or a simple mixer but this problem usually happens with thermostatic units, as Vyv rightly says, crystalline deposits in the cartridge can cause problems, another problem with thermostatic units is that they are designed for working above a given pressure and if the pressure drops below that they do not work correctly, the pump may have become lazy and the kick in pressure may have dropped of the accumulator may not be smoothing out the pressure.
My instinct would be to check the cut in and out pressure against the spec of the mixer and also check the accumulator for pressure balance against the cut in and out. Also remove and inspect the cartridge in the mixer and if necessary replace it. In my experience Jeanneau and Beneteau are pretty good about using standard stuff so a replacement should not be hard to source if needed.

 

[AndrewB]

If you have a simple mixer, my guess would be an expansion tank on the calorifier helping to keep the hot water flow steady, but a faulty accumulator not keeping the cold water flow steady. This is most likely if they have been neglected and so the pressure in both is a little low. Both need to be pumped up occasionally, once a year or so, to the correct pressure. A symptom that the accumulator pressure is wrong is if the pump cuts in and out too frequently, specially when running cold water.

 

[Mistroma]

I have a Jeanneau 42DS and this is all good advice so far. Probably worth checking if you have the same problem on all taps or if it is confined to aft. heads.

1) I've had the pump short cycling and that was fixed in a few minutes so don't know if it impacted the shower temperature. If your pump is stopping and starting very frequently then try pumping up pressure in the accumulator. It's the red tank next to the pump in front of the galley on 42DS (I just used a bicycle pump on top nozzle).

2) I found a huge amount of crud when I cleaned out all the shower heads and taps even though I clean the main filter regularly. So there's a good chance that this is worth doing. The filter parts just undo easily using a suitable spanner but there are lots of tiny filter discs inside.

3) There is a mixing valve on the end of the hot water cylinder. I haven't had problems with this item and would suggest checking items 1 & 2 first. If you still have problems and same fluctuations on all taps/shower heads then the mixer is the next thing to look at.