E7 immersion heater problem

[RBS_GB]

First post, so thanks in advance to anyone who takes the time to reply.

Attached photo is our Super Seven immersion heater. Everything is original from when the house was built in the 80s. We´ve never needed the boost as the water from the E7 is sufficient for daily use, but now we´ve hit a problem.

Using the E7 overnight, the water is not heating to temperature, reaching only 20 deg C. E7 is the lower cable in the photo. Using the boost, for about 30 minutes, it goes up to "hand hot". The E7 timer I´m certain is OK, as the storage radiators are working normally.

The E7 element is clearly heating, but just not enough, so my guess is that either the element is faulty or the thermostat is a problem. Do these systems have separate thermostats for the E7 and boost elements or do they use a common thermostat? Is it possible the element is not giving full power or might be furred up and not heating the water?

Any suggestions on best procedure for fault finding and repair? I´m technically minded, just without any experience of this equipment.

Thanks
Ray

 

[Adam_151]

Assuming it heats a little bit on E7, and this occured out of the blue then sounds like the thermostat has gone dodgy (if it was not heating at all, it could be a few more things; coolness appeared gradually could be limescale buildup), the thermostat is local to the heater... see here for details: //www.diynot.com/forums/viewtopic.php?t=37170&start=36

(take note about what it says about modern stats having overheat cut-offs, and make sure the replacement has that feature, you might also want to swap the one in the boost heater as well)

 

[RBS_GB]

Thanks for the quick reply. It has given me the shove in the direction I needed! I´ve taken off the cover, and can see how the thermostat is the old type, and can easily be replaced. I´ll find a replacement and swap it over, then see how we go on from there.

Thanks a lot for your help.

Ray