Can I switch on an Economy7 immersion heater during daytime hours?

[Serkit]

We are replacing our Economy7 hot water cylinder due to a leak that has two immersion heaters and an indirect coil from our multi-fuel stove. My plumber has only been able to find a cylinder with one immersion connection (plus the two 28mm indirect coil connections).

Is there a way to switch on the immersion heater during daytime hours if we needed to top up on hot water?

Any ideas or advice would be very helpful.

 

[brianmoooore]

Yes, an E7 controller will do as you require.

Horstmann Economy 7 Timer and Boost Control E7Q | Click4Electrics

Buy your Horstmann Economy 7 Timer and Boost Control E7Q from Click4Electrics, Integral time switch and boost control. Boost timer 0-60 minutes. Quartz controlled. 150 hour battery reserve. For use with single or dual element immersion heaters, or with two separate, single element immersion...

www.click4electrics.co.uk

There are also other, simpler devices which just have the boost function.
Alternatively, any competent plumber should be able to fix a second immersion heater boss to a copper cylinder.

 

[Serkit]

Yes, an E7 controller will do as you require.

Horstmann Economy 7 Timer and Boost Control E7Q | Click4Electrics

Buy your Horstmann Economy 7 Timer and Boost Control E7Q from Click4Electrics, Integral time switch and boost control. Boost timer 0-60 minutes. Quartz controlled. 150 hour battery reserve. For use with single or dual element immersion heaters, or with two separate, single element immersion...

www.click4electrics.co.uk

There are also other, simpler devices which just have the boost function.
Alternatively, any competent plumber should be able to fix a second immersion heater boss to a copper cylinder.

Hello Brian and thank you for your reply. I had a poke around on the internet and found this.

Electrisaver Immersion Heater Booster

Is it the sort of simpler device that you were thinking of? It looks very easy to operate and it would replace the function of our second "top" immersion heater. It would be cheaper than having a plumber supply and fit a new immersion heater. I assume that it is installed in the flex to the immersion heater in the airing cupboard?

Yes, an E7 controller will do as you require.

Horstmann Economy 7 Timer and Boost Control E7Q | Click4Electrics

Buy your Horstmann Economy 7 Timer and Boost Control E7Q from Click4Electrics, Integral time switch and boost control. Boost timer 0-60 minutes. Quartz controlled. 150 hour battery reserve. For use with single or dual element immersion heaters, or with two separate, single element immersion...

www.click4electrics.co.uk

There are also other, simpler devices which just have the boost function.
Alternatively, any competent plumber should be able to fix a second immersion heater boss to a copper cylinder.

Hello Brian and thank you for your reply. Was this the sort of simpler device that you were thinking of?

https://www.amazon.co.uk/BRAND-OP-EBT2-ONE-BUTTON-TIMER-ELECTRONIC/dp/B07CT11W6W/ref=asc_df_B07CT11W6W/?tag=googshopuk-21&linkCode=df0&hvadid=375456255828&hvpos=&hvnetw=g&hvrand=10748910570821230398&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1006676&hvtargid=pla-818909378379&psc=1&th=1&psc=1&tag=&ref=&adgrpid=77211061152&hvpone=&hvptwo=&hvadid=375456255828&hvpos=&hvnetw=g&hvrand=10748910570821230398&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1006676&hvtargid=pla-818909378379

It would certainly be cheaper than a new immersion heater and fitting it.

How does it work alongside my existing Economy7 system? I have two electrical supply flex cables in the airing cupboard, one to each immersion heater. Being no expert, I assume that these come from my consumer unit, which switches over at midnight to turn on the Economy7? During the day, after 7.00a.m. the system swiches over again. How do I maintain a live supply during the day or am I overthinking this one?!

 

[brianmoooore]

I don't think the device you have found is suitable. It appears to be just a timer that would be used with your previous set up with two immersion heaters.
The device you need has the 7 hour supply cable and the 24 hour supply cable coming into it, and switches the feed to the single immersion heater between the two. The one I am familiar with is the Horstman E7BX, but following a quick search for one, it
looks like it may have discontinued.
The E7Q, or its digital equivalent is the most commonly used device these days, since it allows the start of the overnight heating of the hot water to be delayed by a few hours, reducing losses from the cylinder. This type of timer only requires a single 24 hour supply, and can be used with either one or two immersion heaters.
One problem with just a single immersion heater is that it heats all of the water in the tank, which is fine if you're heating it on reduced price electricity, but it limits you to heating all of the water on full price electricity as well, if you want to boost it during the day. A second immersion heater, intended for use with a daytime boost is typically mounted half way up the cylinder, so that it only heats the top part of the tank, getting this much smaller quantity of water hot using much less expensive electricity.
Cylinders with a coil and two immersion bosses are available. Your plumber needs to try harder.