European Hot Water Tank Specifications

[optimtor]

I posted a while ago about a leaking blow off valve (Temperature / Pressure) on my hot water tank. It still has been leaking and the red knob finally corroded off.

The boat is a UK built Southerly 110.

It seems like I need a new valve. BUT, before I source the (probably Italian part) It occurred to me that maybe I'm leaking because I'm over pressurizing my tank.

The Shurflo pump pressurizes to 55 psi and some of the references I've seen to European blow off valves reference 2.5 bars. About 36 psi.

There are no markings on the hot water tank I can find.

Does anyone know if there are pressure standards for European hot water tanks on boats? And what those standards might be?

[CarstenWL]

... there is no standard (that I am aware of), often you see also 6bar used. Depending on the pump, expansion tank, ...

Regards,

Carsten

[chuckr]

Not sure what all this means -- but I just put in a new 30L quick tank in my Jeanneau. In the specs section of the manual it reads
tank pressure during testing 800kPa
maximum working pressure 600kPa

it say 1Bar=100kPa

hope that helps

[Dockhead]

I think your logic is correct.

Your pressure relief valve may not be specified correctly, or it may be defective. In any case, it should certainly not be set to blow off at a pressure below the cut-off pressure of your water pump.

You can get them with different pressure values:

Pressure Relief Valve 4 Bar

[optimtor]

Originally Posted by Dockhead

I think your logic is correct.

.....

You can get them with different pressure values:

Pressure Relief Valve 4 Bar

I think it's the other way around? I think I need to get a water pump that cuts off below the blowoff valve limit. That way I don't blow up the tank

As an aside, the 55 psi does really get the water out.

[wiekeith]

I have a European (Italian) calorifier, and the manual states that it has been pressure tested to 5bar (actually states 500kPa), so I guess the relief valve will operate at a pressure lower than this?

[a64pilot]

Most pumps you can adjust the pressure, but if the knob is corroded of the T&P valve, I'd replace it.