Horstmann Economy 7 Quartz heater always 'on' - doesn't turn off according to pre-set times on clock

cherylleack · Feb 22, 2022

Hi all,

I have quite an old Horstmann Economy 7 Quartz water heating system in my flat (installed around 2007). It's been working fine until the last month, now the water heater always seems to be 'on'. The clock is set to the correct time, and even when it is the middle of the day when the heater shouldn't be on, the neon off peak indicator light is on and the water is still being heated.

The only way to stop the heater is to switch the water heater to 'off', when the switch is set to 'timed' the water is constantly being heated no matter what time it is.

Is this a problem that can be fixed? Or does it need replacing? If so, does it need replacing with the exact same controller... it is quite old and I'm struggling to find the exact one, I'd like to avoid having a whole new system installed if possible!

brianmoooore · Feb 22, 2022

Still available new, and there is also an electronic version which is interchangeable.
Switch the electricity OFF at the fusebox main switch, remove the two screws holding the front of the E7 in place, and you will see that there are 5 push on connectors from the front part to a terminal block fixed to the case.
Is there any sign of a small darkened area on the front of yours?

cherylleack · Feb 22, 2022

brianmoooore said:
Still available new, and there is also an electronic version which is interchangeable.
Switch the electricity OFF at the fusebox main switch, remove the two screws holding the front of the E7 in place, and you will see that there are 5 push on connectors from the front part to a terminal block fixed to the case.
Is there any sign of a small darkened area on the front of yours?

Thanks Brian, I will have to check this at the weekend, it is a tenanted flat and I can't get in until then. Would this indicate some of the wiring has been fried?! I've seen lots of Horstmann Economy 7 controllers but they don't look the same as mine, neon indicator lights are in a slightly different place etc. I wasn't sure if it had to be exactly the same on the front, or whether the push connectors would be universal.

brianmoooore · Feb 22, 2022

The microswitches in the mechanical version of the E7 have been known to burn up. They are fitted just behind the faceplate, so the heat can discolour a small area on the front.
AFAIK, all models have the same terminal block and will fit the same enclosure, so will be a quick fix if the terminals are all in good order.

littlespark · Feb 22, 2022

They are notorious for burning out.
The connections carry the full 3kW load of an immersion heater… so can get quite hot.

If you get the same type, it is a simple enough job. Just crimped wires that push onto the terminals. And they’re numbered.
However, as it’s a rented property, I’d advise you get an electrician to change.

I wonder if someone’s done something daft here and fitted a bypass switch?