Electric only hot water

[orval]

Hi,

I was looking at my girlfriend's hot water system the other day to try and work out why her bills are so high. I've only ever had gas boilers so I'm not familiar with electric only systems.

I was quite surprised to find that it is simply an unvented cylinder (Heatrae Sadia Megaflo) with two immersion heaters. Both rated at 2.76kW and on their own switch (didn't notice if they were fused tbh.)

She leaves the bottom one on all the time, and calls turning the top one on "putting on the immersion". There are no timers that I can see, and there's only one meter so no Economy 7.

So, is this a typical type of install? (This is a block of flats converted in an old mill.)

What is the most efficient way to run this system?

Bottom line: can she save any money!?

Thanks,
Orval

 

[Aragorn84]

Bottom line: can she save any money!?

How is the house heated?

If its electric heating, that will have a much larger impact on bills than the water will.

If its gas/oil, then why isnt the boiler being used to heat the water?

Does she use a lot of hot water from the tank? For instance if theres a electric shower and appliances are all fed from the cold side hot water usage will be pretty low, whereas if she brims the bath every night its a different story!

 

[orval]

There are electric heaters. The place needs very little heating. She only uses one of the heaters and not for very long at a time.

The hot water is on 24/7, and yes I guess she uses a lot because she has a bath every evening.

 

[Whitespirit66]

Sounds like an expensive way of heating hot water. Best way if it has to be electric, is to have economy 7. The bottom element will heat the whole tank in the early hours on cheap rate.

The top element will be used if she needs more hw to tide her over until the whole tank is re-heated the next morning. This will heat only approx the top half of the tank, using standard rate elec - so only to be used for 'topping up' if needed.

Can't think why she has to turn the top element on if the bottom one is on all the time, unless it's broken. What temp is the hw set to?

Her bills must be huge!

 

[orval]

She puts it on if we both have a bath, so I assume there's not enough in the bottom of the tank for two baths. I'll ask her later.

When you ask about what temp it's set to, do you mean the little thermostat control under the cover? I'll have to get her to have a look, although I expect she'll not be able to remove the cover!

I have just read something about combined meters for Economy 7, so I guess she could have one of those. Altough I wouldn't know how to tell.

 

[Whitespirit66]

She puts it on if we both have a bath, so I assume there's not enough in the bottom of the tank for two baths. I'll ask her later.

When you ask about what temp it's set to, do you mean the little thermostat control under the cover? I'll have to get her to have a look, although I expect she'll not be able to remove the cover!

I have just read something about combined meters for Economy 7, so I guess she could have one of those. Altough I wouldn't know how to tell.

Yes, the thermostat under the cover.

I would be surprised if it wasn't E7, especially as you now say it's electric heating. The bottom element is left swiched on, but will only come on in the early hours on E7 timings - so not actually powered continuously.

You need to see the bills and meter to know what tariffs she's on.

 

[orval]

Now we're getting somewhere! She's just sent me a picture of her usage from a phone app. There are day and night readings, although she'd not mentioned that to me bofore. Doh.

The usage for the last quarter was 2100kWh on the day tariff and 373kWh on the night tariff.

I'm going to do some googling to see if that is reasonable for one person in a one-bed flat.