Good evening all, I have a query regarding an immersion tank.

I received a call from a new client asking do I fix immersion tanks to which I told her it’s probably best to get a plumber out as he can eliminate the problem and change the element if required which would save her money.

I won’t go into too much detail but it turns out the plumber just changed the immersion element and billed her, the next day later she called me saying that it’s not working again, could I pop over?

After taking a look I soon realised that the timer was an old rotary time guard which isn’t ideal as it hasn’t got a boost function and which had also malfunctioned resulting in a previous DIYer bypassing it resulting in the immersion running 24hrs a day. (This has since been upgraded)

I tested the mains in at the tank which had voltage then nothing coming out of the thermal cut out which I reset then supplying voltage to the element (Could here it heating) I then assured her I had sorted the problem as I had changed the time clock and reset the thermal cut out.

I received another phone call the following day saying it’d stopped working yet again.The only thing left do was to change the thermal cut out for a new one which I did and it worked for 3 days only to trip again today!

I have done way more than I would normally do and this job has cost me money!, I’ve since walked away from the job on good terms explaining to the client I can’t do anything else. In 20 years of doing this I am dumbfounded!

Any ideas on possible causes? I had made sure the thermal cut out was set no higher to 65 degrees? It is an electric only flat with a dual element mega flow type tank although the middle element isn’t being used at all as they don’t have eco7.
 
Last edited:
Good evening all, I have a query regarding an immersion tank.

I received a call from a new client asking do I fix immersion tanks to which I told her it’s probably best to get a plumber out as he can eliminate the problem and change the element if required which would save her money.

I won’t go into too much detail but it turns out the plumber just changed the immersion element and billed her, the next day later she called me again saying that it’s not working again, could I pop over?

After taking a look I soon realised that the timer was an old rotary time guard which isn’t ideal as it hasn’t got a boost function and which had also malfunctioned resulting in a previous DIYer bypassing it resulting in the immersion running 24hrs a day. (This has since been upgraded)

I tested the mains in at the tank which had voltage then nothing coming out of the thermal cut out which I reset then supplying voltage to the element (Could here it heating) I then assured her I had sorted the problem as I had changed the time clock and reset the thermal cut out.

I received another phone call the following day saying it’d stopped working yet again.The only thing left do was to change the thermal cut out for a new one which I did and it worked for 3 days only to trip again today!

I have done way more than I would normally do and this job has cost me money!, I’ve since walked away from the job on good terms explaining to the client I can’t do anything else. In 20 years of doing this I am dumbfounded!

Any ideas on possible causes? I had made sure the thermal cut out was set no higher to 65 degrees? It is an electric only flat with a dual element mega flow type tank although the middle element isn’t being used at all as they don’t have eco7.
Thermostat on the elements not set correctly??, jusy a thought.
 
Good evening all, I have a query regarding an immersion tank.

I received a call from a new client asking do I fix immersion tanks to which I told her it’s probably best to get a plumber out as he can eliminate the problem and change the element if required which would save her money.

I won’t go into too much detail but it turns out the plumber just changed the immersion element and billed her, the next day later she called me saying that it’s not working again, could I pop over?

After taking a look I soon realised that the timer was an old rotary time guard which isn’t ideal as it hasn’t got a boost function and which had also malfunctioned resulting in a previous DIYer bypassing it resulting in the immersion running 24hrs a day. (This has since been upgraded)

I tested the mains in at the tank which had voltage then nothing coming out of the thermal cut out which I reset then supplying voltage to the element (Could here it heating) I then assured her I had sorted the problem as I had changed the time clock and reset the thermal cut out.

I received another phone call the following day saying it’d stopped working yet again.The only thing left do was to change the thermal cut out for a new one which I did and it worked for 3 days only to trip again today!

I have done way more than I would normally do and this job has cost me money!, I’ve since walked away from the job on good terms explaining to the client I can’t do anything else. In 20 years of doing this I am dumbfounded!

Any ideas on possible causes? I had made sure the thermal cut out was set no higher to 65 degrees? It is an electric only flat with a dual element mega flow type tank although the middle element isn’t being used at all as they don’t have eco7.
Replace the stat that includes the limit stat
 
As Ferg suggested, check the connections on the stat, a poor connection will produce heat which will fool the stat or operate the OH cutout.
 
Are the correct element and thermostat for the tank fitted? If this is a pressurised Megaflow tank, they tend to specify the correct element and correct thermostat for the specific tank. I've come across one before where a plumber decided to put in presumably whatever he happened to have with him, and had these sort of problems (if I recall, he'd fitted a much shorter thermostat than he should have).
 
Good evening all, I have a query regarding an immersion tank.

I received a call from a new client asking do I fix immersion tanks to which I told her it’s probably best to get a plumber out as he can eliminate the problem and change the element if required which would save her money.

I won’t go into too much detail but it turns out the plumber just changed the immersion element and billed her, the next day later she called me saying that it’s not working again, could I pop over?

After taking a look I soon realised that the timer was an old rotary time guard which isn’t ideal as it hasn’t got a boost function and which had also malfunctioned resulting in a previous DIYer bypassing it resulting in the immersion running 24hrs a day. (This has since been upgraded)

I tested the mains in at the tank which had voltage then nothing coming out of the thermal cut out which I reset then supplying voltage to the element (Could here it heating) I then assured her I had sorted the problem as I had changed the time clock and reset the thermal cut out.

I received another phone call the following day saying it’d stopped working yet again.The only thing left do was to change the thermal cut out for a new one which I did and it worked for 3 days only to trip again today!

I have done way more than I would normally do and this job has cost me money!, I’ve since walked away from the job on good terms explaining to the client I can’t do anything else. In 20 years of doing this I am dumbfounded!

Any ideas on possible causes? I had made sure the thermal cut out was set no higher to 65 degrees? It is an electric only flat with a dual element mega flow type tank although the middle element isn’t being used at all as they don’t have eco7.
The big thing in the middle where is the wires connect that is the thermostat.
It just plugs into the element
 
As Ferg suggested, check the connections on the stat, a poor connection will produce heat which will fool the stat or operate the OH cutout.
The heater apparently doesn't have a stat?
[automerge]1588616151[/automerge]
The big thing in the middle where is the wires connect that is the thermostat.
It just plugs into the element
Oh my
 

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Scratching my head over immersion heater!
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