Electric immersion tank overflowing into Cold Water Cylinder

Blisterman

The immersion tank has started, at the end of its nightly heating cycle pumping hot water out through the overflow pipe at the top into the cold water cylinder.
Not just a trickle, but gallons and gallons, to the point where the cold tap runs scorchingly hot.
Obviously this is an issue for all sorts of reasons.
Does anyone know what might be causing this?

The immersion is not connected to a central heating system. There doesn't seem to be any obvious way to reduce the amount of time the Immersion heats for at night.
It's a Horstmann e7 quartz timer and an ideal immersion heater. 2/3KW.

Sleeper12

Blisterman wrote: »

The immersion tank has started, at the end of its nightly heating cycle pumping hot water out through the overflow pipe at the top into the cold water cylinder.
Not just a trickle, but gallons and gallons, to the point where the cold tap runs scorchingly hot.
Obviously this is an issue for all sorts of reasons.
Does anyone know what might be causing this?

The immersion is not connected to a central heating system. There doesn't seem to be any obvious way to reduce the amount of time the Immersion heats for at night.
It's a Horstmann e7 quartz timer and an ideal immersion heater. 2/3KW.

The immersion has a thermostat. This could be set too high or more likely, as its just started happening the thermostat has blown. It's not an expensive fix

Wearb

You should have an isolation switch to turn it off if not turn it off at the trip switch. There have been instances of that sort of cycle eventually softening the storage tank to the point of it collapsing and pouring scalding water through the ceiling onto the occupants of the bed below.

K.Flyer

The thermostat has stopped working and needs to be replaced.
If this is something that you are not familiar with, you will need to get an electrician out to do it for you.
Changing the time duration will not resolve the problem.