Looking for tips for the most efficient ways to use an electric boiler on Economy 7

Hello! I’ve just moved into a flat that is electricity only, no gas. It’s also an Economy 7 metre, which I’ve never encountered before. And it’s the sort of boiler you have to switch on and off, with no timer.

So I’m looking for the most efficient ways to heat up water, both for the sake of my bills and the sake of being green.

It’s currently set to low and I turn it on for an hour in order to have a shower and wash the dishes, but it doesn’t stay hot for all that long. I normally sleep 1.30am-10.30am so I’m concerned that leaving it switched on all night wouldn’t be that cost-effective with Economy 7, since I’m guessing the hours are btwn 11pm-7am, and I’d only turn it off at 10.30am. If I leave it on 11pm-1.30am, I doubt the water would stay hot enough to have a shower when I wake up. Any advice or ideas? It seems like Economy 7 is great for people whose schedules fit, and not so great for people like me.

So, during the day, is it better to turn it up to a hotter temp and leave it on for an hour, or have it at this lower temp and leave it switched on for longer?

Any other tips welcome!

Economy 7 provides for a dual-rate electricity supply - a slightly-higher-than-standard day rate, and a much-lower-than-standard night rate (for 7 hours, hence the name).

Which 7 hours you get at cheap rate traditionally varied by region, and is controlled by your meter (AIUI), and a 2/5 split in the hours is quite common (eg for me, my E7 night hours are 10.30pm-12.30am and 2.30am-7.30am [GMT]).

Does your boiler feed a hot water cylinder? Or does it just supply [near-]instantaneous hot water on demand?

If it heats up a HW cylinder, then you’re probably better off investing in a timer for the boiler, and letting it run during E7 hours (assuming the cylinder is well-insulated - or even getting it insulated as well).

Even if you were to run the boiler for longer than you do under manual control (to get the water hotter so that it stays hot enough for later), using it on the vastly reduced night rate should work out better (the night rate is a little under half the day rate, so you can double the run time for slightly less cost, but I doubt you’d need to do as much as that).

Also, are you sure the shower is reliant on the boiler for hot water? Many showers do their own water heating (while in use).

Hello Steve! Thank you so much for responding, and I’m sorry it’s taken me months to get back to you (I am struggling with my health).

I have called up the boiler company and they said it’s not possible to install a timer for the boiler. I am surprised at this. I’m unsure whether to take their word for it or try and get a plumber to look at it.

I’ve looked it up and for my area the Economy 7 hours are between 11pm-7am. Sometimes I switch on the heater to do washing up at 11pm for a short while, but I normally shower in the daytime and since I’m a night owl I can’t turn it on before 7am.

The current way I’ve been doing it is to turn it on for 30 mins at just below the ‘e’ setting, and turn it off when the dial is vertical. This gives me just enough hot water for a 5-10 min shower. I leave it on for longer if I need to wash my hair. I’m sure the shower is reliant on the boiler for hot water because of the number of times I’ve run out of hot water while showering. I have learnt to leave the boiler on when I shower if I’m unsure there’ll be enough hot water - I imagine this makes it run out of hot water more slowly. It’s turned into a bit of a game for me - can I shower faster than the hot water runs out?

I’ve also found that if I want to have a bath, it’s best to do it in two loads - run the hot water out from the boiler, turn off the tap and let it heat up again, then run the second half of the bath. I’m probably doing something wrong there but it seems to work alright.

I think my ways of doing things have been ultra-efficient - I only ever heat up the water I need, and that’s reflected well in my bills. It does feel like a balancing act though. So I am quite disappointed that I can’t install a timer for the boiler, it would have made my life easier. Leaving it on all night while I’m asleep would certainly come out more expensive because the maximum time I’d have it on is 1hr during the day.

Thank you again for your very useful comment, I wish that I was able to get a timer for this boiler.