Over-night immersion not coming on

A Shropshire Lad · 15-09-2019 11:39am #1

I have an electric water immersion heater, which is working correctly, as I can use the boost function and it heats up the boiler. However the timed over night has suddenly stopped coming on the last few nights. It was working fine before that

Any ideas what might be the problem ?

TheChizler · 15-09-2019 11:42am

What kind of controller is it? What have you checked?

A Shropshire Lad · 15-09-2019 12:01pm

TheChizler wrote: »

What kind of controller is it? What have you checked?

The name of the controller is Horstmann Economy 7 Quartz, electro mechanical water heating control.

I dont really know much about these things, what should I be checking ?

K.Flyer · 15-09-2019 2:09pm

Either the Off-Peak immersion heater is burnt out, or the Over-Heat cut out has tripped on the immersion thermostat.
Unless to have a multimeter and know how to use it there is not a lot you can do.
If you are confident in working with electrics you could check the over heat cut off by isolating the supply and removing the cap on the immersion.
It is usually a small white circular thing with a small black button in the middle. Get something to push in the black button. If you hear a click, you have reset it.
Sometimes the reset is on the thermostat, but a picture of yours would make it easier to identify.
If the immersion is burnt out it can be a tricky job to change as its the bottom immersion and you cannot empty the tank just by running a tap.

TheChizler · 15-09-2019 2:35pm

Obvious things first, is the time set correctly, is the timer programed right? If so does it normally give an indication when it's turned on? If so I'd then start probing with a multimeter but you might not be comfortable doing that.

When you say it heats up the boiler, do you mean it turns on a different boiler or it heats the hot water cylinder electrically via the immersion? If the immersion works when you boost manually then it points towards a fault in the controller.

A Shropshire Lad · 15-09-2019 2:47pm

K.Flyer wrote: »

Sometimes the reset is on the thermostat, but a picture of yours would make it easier to identify.
.

I have attached two photos of my setup

K.Flyer · 15-09-2019 3:54pm

That immersion looks to have been recently replaced, so hopefully its just a limit stat issue.
ALWAYS ENSURE THAT YOU HAVE FULLY ISOLATED THE ELECTRICAL SUPPLY BEFORE ATTEMPTING ANY ELECTRICAL WORK!
Ideally you should check the connections with a meter to ensure that the supply is isolated.
Make sure you have the fuse board trip switch for Immersion pulled down to isolate electrical supply to the clock / immersion.
Check at the time clock that the lights are not coming on and press main switch on the clock to off.
Remove the metal cap on bottom immersion.
Locate the high limit cut out stat which will have two WHITE wires connected to it.
Carefully push the small centre button inwards and listen for a soft click.
Replace the cap correctly and replace the retaining nut.
Push the fuse board trip fully up.
Turn the main timer switch to Timed and rotate the larger timed dial until the light comes on.
Leave it for an hour or so and check for hot water.

Over-night immersion not coming on

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