HW too hot, thermostat set at 60c

[mikehowett]

Hi,

I'm having some trouble with my HW, the thermostat on the hot water cylinder is set to 60c but the water coming out of the taps is much hotter, almost scalding hot. I've replaced the thermostat with a new one and the problem remains.

Currently the water is too hot, however removing the thermostat from the tank reveals that the surface of the tank is cold to the touch, i'm guessing this has something to do with the problem, the thermostat thinks the water is cold so keeps calling the boiler to heat it. Is my hot water cylinder faulty?

Any help would be much appreciated!

 

[AfterburN003]

Stupid question first......have you cut away the insulating foam so that the cylinder stat is touching the copper of the cylinder?

 

[spikebmth]

have you tested the hot water temperature at the tap with a thermometer?

60c is very hot to put your hands in, to give you an indication, a jacuzzi is set at 36c.

As suggested, check the cylinder stat is touching the cylinder.

If the water is really too hot, then i;d suggest you change the cylinder thermostat for a new one.

 

[mikehowett]

Stupid question first......have you cut away the insulating foam so that the cylinder stat is touching the copper of the cylinder?

Yes, the foam is cut away exposing the bare copper. The tank is full of hot water, yet the copper surface where the stat goes is cold to the touch, the pipe from the top of the cylinder that feeds the taps is very hot.

As stated in my op, I have already tried changing the tank stat.

 

[seco services]

where is the tank stat fitted from the base of the cylinder ?

 

[spikebmth]

the cylinder stat should be fitted about a third of the way up from the bottom.

Check the immersion heater is switched off.

 

[mikehowett]

Stat is fitted a third of the way up, immersion is definitely not on.

 

[JohnD]

What temperature is the boiler set to?

 

[seco services]

What temperature is the boiler set to?

whats that prove ?

 

[JohnD]

We don't yet know what temperature the water coming out of the hot taps is.

I was wondering if the coil in the cylinder was so hot that the stratified water at the top of the cylinder was already "very hot" before the lower part of the cylinder had warmed up.

A related thought was that there might be a leak or constant usage of hot water, so that cold water was constantly or frequently flowing into the cylinder, keeping the bottom layer cold and causing the cyl stat to call for heat which made the top layer too hot..

I have had a similar problem, and my workround was to put the cyl stat higher on the cyl. This does however increase the reheating lag once you have used the hot water from the top of the cyl.

 

[seco services]

yes i get where your coming from john.