UK Horstmann Electronic 7 only working with boost, not timer

[Jessaliceallan]

Hi,

We have just moved into a new flat with the old Horstmann electronic 7 timer for our immersion boiler. We just moved from a flat with the exact same system and never had any issues. We have set the timer and the times for the off peak boiling and have had no hot water for 3 days. The boiler works when we press the boost button after we filled it up with water, but still will not work on the times settings. The light for off peak shows but the water never boils. Can anybody help with this please? We cannot keep pressing boost everyday!

Thank you in advance

 

[telectrix]

is the timer actually running. as in, does the time display alter.

 

[loz2754]

It has all the signs of a faulty bottom immersion element, or if you're lucky, the built in overheat stat in the element. It needs testing by someone with the proper test gear.

 

[telectrix]

1 or 2 members in the birmingham area, sure 1 of them could borrow a steam powered test meter for a day.

 

[Jessaliceallan]

is the timer actually running. as in, does the time display alter.

Yes it does, it’s set to the correct time and when it moves into the time of our off peak setting the light comes on but the boiler never boils. Thanks

 

[brianmoooore]

Are there two separate immersion heaters, with a flexible cable going to each, in your boiler?

 

[Jessaliceallan]

Are there two separate immersion heaters, with a flexible cable going to each, in your boiler?

I’m not sure sorry, I think there might be. This is a picture of the inside. It’s working with the boost button but not with the timer so maybe that wire is broken?

 

[littlespark]

It needs tested properly see if there’s power at the heater when there should be.

We’re just stabbing in the dark

 

[Avo Mk8]

I’m not sure sorry, I think there might be. This is a picture of the inside. It’s working with the boost button but not with the timer so maybe that wire is broken?

To summarise, as has been said above, usually the Horstmann timer is connected to two immersion heaters, one about half way up the tank, and one near the bottom of the tank. If you move your ironing board, you might see the two covers, or ends of them, poking out of the cylinder. Each would normally be wired separately to the Horstmann.
When you press the boost button, the upper immersion heater is switched on.
When you put the timed program on, the lower immersion is switched on.
The lower one does the hard work, and as a result is often the first to fail. That said, the failure may not be the element itself, it could be the internal thermostat, or the cutout. Or if moving things in the cupboard might have pulled on the wire, it could be that, but less likely. You need someone competent and with testgear to diagnose the problem.

Your cylinder seems to have been installed in 2006, so the bottom immersion (and its thermostat/cutout!) has done some 15 years service, so not unheard of for it to pack up.

If someone tests it and discovers the lower immersion element has failed, a repair will likely require the water to be drained out of the cylinder, and the element unscrewed and replaced with a new one. This is a job that some electricians feel should be done by a plumber, so if you get a tradesperson to look at this, worth asking if they are happy to do the whole job, including replacement, if it comes to that!

 

[brianmoooore]

This is a more modern hot water system than I first assumed, and the actual cylinder is enclosed in a white steel casing. making observations a bit more difficult.
Is your hot water only produced by electricity?
How many electrical cables are connected to the boiler?