Unvented cylinder, stats keep failing

[MOSSEP]

Unvented water heater question - Gledhill direct 90l


Was called to a club and the water was getting too hot, done some checks and the thermostat was not working (not turning off). Changed the stat and all worked, called back after 2 weeks and it had gone again, put it down to a faulty stat and duly replaced it. Tested the water temp after it had got to temperature and it was reaching a nice 59 degrees, voltage reading around 244v


Had a call again this week saying the water temp has started getting too high, this stat has managed about 4 weeks until it has failed. Going to go back and measure the resistance of the element, but never had one where that has failed and caused an increase in load.


Any ideas other than changing the element?


Cheers


Martin

 

[Whyme]

Thought about getting a sparky in sounds like there getting fried?

 

[Destroyer2813]

Was something similar couple months back in the plumbing section direct cylinder going through immersions every couple of months not sure on the outcome though

 

[MOSSEP]

I am one, but cannot see an electrical reason for it. The voltage is fine, but not come across a element where the resistance has lowered before. There are no loose connections at all.

 

[Chalked]

Could be wired the wrong way, so will come on when above 60! Easy to check with multimeter.

 

[MOSSEP]

Really? ive never seen one where that is possible, these ones only have 2 terminals

 

[townfanjon]

Dare i ask whos stats are fitted

 

[gassafe]

Could it be the immersion element frying the stats? I would drain down & fit a new immersion which would come with the stat?

 

[MOSSEP]

Manufactures own, sourced from gledhill. Thats what odf.

 

[MOSSEP]

Going to recommend changing the element and see if that fixes it in think. Ive worked on loads of these but never had this happen, if an element fails its usually a dead short or open circuit

 

[Dotty]

Not familiar with Gledhill. Has it got a sacrificial anode?

Could be that needs replaced.

 

[stevetheplumber]

Not familiar with Gledhill. Has it got a sacrificial anode?

Could be that needs replaced.

cant see how the anode can affect the thermostat as its normally in a pocket and no contact with water

 

[Dotty]

cant see how the anode can affect the thermostat as its normally in a pocket and no contact with water

No, but it will affect the element. I had something similar once, turned out to be the element, nearly drove me bananas!