Hot water thermostat

[brianposter]

I am having trouble understanding a hot water thermostat which does not behave as expected. What does the "reset" button do, and is it necessary to use it after adjusting the temperature dial ?

 

[snowhead]

No it wouldn't need resetting after any adjustment.

The thermostat has the normal variable control from the dial and a fixed overtemperature setting.
If the the normal control fails (or the cylinder goes over temperature for other reasons) then the over temperature stat trips and would require investigation as to why and reset.

Other reasons the Overtemp might trip are if the cylinder also is heated by solid fuel or solar or gas and the cylinder stat controlling the gas boiler has failed.

 

[telectrix]

what he said^^^^. the reset button is on the failsafe secondary stat.(thermal overload) that operates to prevent water from boiling should the main stat. fail. there have been a few cases wher, on tanks witout this safety feature, the tank has exploded and in 1 case i heard of, a baby sleeping below was killed.

a recent case of one that had tripped, some company in London (mention no mames) charged £250 + VAT to press the reset.

 

[brianposter]

Thanks. Looks like I will have to spend a little longer trying to work out why the thermostat appears to work in reverse.

 

[Wilko]

Hi - if the reset button is popping out, it’s time to replace the unit in my opinion.

 

[ruston]

Are you in a hard water area?
What exactly is happening?

 

[brianposter]

Simply tried to adjust the thermostat down twice, but the water temperature appears to have increased. Looks like it is a question of trying a few more times.

 

[ruston]

The element may be covered with a layer of lime scale and giving a false reading. Has this happened over time ?
Have you any equipment to test the stat?

 

[telectrix]

looking at your photo, the stat is clockwise to reduce temp., the opposite of what you would think. are you confused with poor (beer induced) eyesight?

 

[tony clark]

when you sole you stat problem se the stat @60 degrees to prevent legionnaires.

 

[ruston]

when you sole you stat problem se the stat @60 degrees to prevent legionnaires.

My mate a plumber says world cup 66 is ideal lol.

 

[brianposter]

Have now managed to adjust the temperature although I do not understand why the first attempts failed.
Thanks everybody.