tank stat help

[James]

I have a customer, a butchers who have a hot water tank to run taps for washing hands and equipment etc.

normal domestic cylinder with an immersion heater.

stat keeps tripping on over temp and needs to be manually reset.

they are using lots of hot water all through the working day.

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I have replaced the stat before but it only seems to fix the problem for a short while, stat has not welded closed.

I seem to recall that you can get a red topped version that has its safety function set at 95 degrees instead of the normal 90 degrees.

Am I imagining this or can I get one?
If so please post a link to somewhere I can get one.

many thanks.

 

[Wilko]

Hi - not your answer (sorry) but it’s not normal to have the safety stat tripping. Why doesn’t the first 60 degree stat trip? Anyway maybe the element is furred with limescale so the water isn’t contacting and isn’t taking the heat away fast enough. So perhaps take out the element and clean / replace it. Just a thought .

 

[James]

Hi - not your answer (sorry) but it’s not normal to have the safety stat tripping. Why doesn’t the first 60 degree stat trip? Anyway maybe the element is furred with limescale so the water isn’t contacting and isn’t taking the heat away fast enough. So perhaps take out the element and clean / replace it. Just a thought .

its a strange one, element was changed with new stat about 12 months ago.
3 months after, was tripping over temp.
changed stat FOC
again, similar problem is occurring.

my only thoughts are that the element is running almost 100% of the time and causing the stat to trip into safe mode, possibly due to the fact that the current to the element is passing through the stat and causing it to heat up.

may have to add a contactor to remove current flow from the already hot thermostat?

 

[Leesparkykent]

Was a cheapy immersion fitted? I would get a titanium one fitted.

 

[freddo]

There was a bad batch of stats a while back where the overheat would start to trip before the operating stat opened. Make sure the stat is the correct one, they differ by length and mounting orientation.