Hot water tank

[airbear1four]

Hi all,
I am a proud new Jeanneau SO36i owner located in Spain, second hand (of course), and I am trying to get the boat up and working in all aspects. For the time being, most of the issues are going in the good track but there is one that, so far, is resisting my DIY abilities. It is the hot water tank. It does work, so it heats water, but it is delivering too little amount of it through the line. I have checked the lines, the fresh water pump works alright, the valves, looked for any air leaking in the ducts, with no success. What should I look to? What could the problem be?
Thanks a lot for all the hints.
Fair winds.
A.

[ForGrinsToo]

If the cold water runs well at the galley sink, but hot does not, look for a kink in the braid-protected water line between the tank and the red PEX. The undersink lines are pretty much a straight shot to the galley sink and unlikely to have gotten pinched or kinked. Then look for a kink in the braid-protected line that comes from the blue PEX to the boiler. With the pump enabled, you could try the pressure relief valve which has a rubber hose directed to the bilge; water should gush. If all those check out, then you may have a problem with the mixing valve at the top of the tank; it's supposed to apportion flow between effluent from the tank and the cold supply. Mine is stuck; I am reluctant to try to move it because I don't have a replacement at hand.

Note that the hot water flow is always significantly less than the cold at the galley sink (due to all the plumbing), but you should still get good aerator function for the hot at the sink.

Geoff

[Don Reaves]

I’ve never noticed any difference in the pressure of hot versus cold water in the galley on my SO35. I wonder if it depends on which model boat you are talking about.

[sailbleu]

Drain the boiler and leave the drain open , try to connect a hose to one of the taps ( hotwater mode ) and blow towards the boiler , that way you know the line is clear , or not . Once the water is out the air should pass through easy . Could be a blockage of the hotwater line in the boiler itself . At least you ruled out that possibility .

Regards

[ForGrinsToo]

Dec 13, 2019 3:03:46 GMT Don Reaves said:

I’ve never noticed any difference in the pressure of hot versus cold water in the galley on my SO35. I wonder if it depends on which model boat you are talking about.

Don,
Do you have a mixing (apportioning) valve on the tank outlet? I've figured that's the reason for a difference. It's less noticeable in the galley than in the head.
Geoff

[Don Reaves]

I’ve never seen such a valve. But I’ve not looked for one either. I can tell you that the water at the galley faucet is extremely hot after running the engine for quite a while. So it doesn’t seem likely that it’s being mixed with cold water.

[alenka]

After renewing the hot water tank on our 43DS the water used to cycle hot to cold and back again in both showers, albeit that a stable pressure and temperature was at all other taps.  There was no mixer valve at the tank on the new installation and I am not sure what the old setup was.

The problem was solved by adjusting the gas pressure on the accumulator that keeps constant pressure in the system. This was done using a cycle foot pump.

[Chris Meyer]

There should be a pressure relief valve on the back of the hot water tank along with a drain valve to drain it.  If either of these are open, the hot water pressure won't work.   Hope you looked at those.

[ForGrinsToo]

Hot water tank in a US-built 2010 36i - I don't have a better photo than this:


www.23hq.com/ForGrinsToo/photo/63619181/original

At back left is a blue PEX line coming off a tee. Cold water from the pump splits at that tee to go through a braided flexible line to the tank where it enters a run-tee. A branch from the run-tee goes to the mixing valve (circled) on the hot outlet at the top of the tank. I don't know if that valve is actually thermostatic, but it is an obstruction in the hot water flow.  One effect it has is to make draining of the tank for winterization very, very slow.  Another is that hot water flow to the galley sink (and the rest of the boat) is less than cold water flow.

So if airbear can't find kinks in either of the two braided lines (in and out), that valve may be the problem. Mine is stuck. I don't want to force it for fear of what might give.  The valve can be sourced from Quick or a number of chandleries for about $150.

And to be fair, Airbear's 36i was most likely built in France and may be plumbed differently.

Geoff

[sailbleu]

It seems the TS isn't very interested in the suggested solutions and/or response from other members , so why bother any further .

As to less hot water pressure I can vouch a thermostatic mix valve reduces the flow significantly , but for us the advantage of a stable temperature exceeds the disadvantage of less pressure/flow .

Regards

[alenka]

I can see where sentiments are coming from Sailbleu but often such threads are very interesting and informative to others.

[airbear1four]

Thanks to all for the suggested solutions. I really appreciate. I am sorry for not having replied earlier, as I was "in drydock" following med treatment. I now feel better and able to deal with the boiler. I'll post my findings for the benefit of others. Merry Christmas.
A.