immersion Heater mystery? (Ed.)

[amosbrown1]

Can emersion heaters stop working intermiddedly?
Im getting in a flap and I dont know much about DIY. Im panicking because im going into hospital next week for major surgery and live alone and today find that my water would not turn on! When I turn on the E7 Emersion heater both the top booster and bottom tank switch dont turn on! Im familiar with the re-set buttons and an electrician walked though this process with me, and still nothing!. Anyway based on that the electrician said he's come round tomorrow but now he cant, , I only have the weekend really. Anyways, after the switches not working after trying multiple times (and after using hot water so its not that there is already too much hot water for it to switch on) ive just tried the booter switch once more randomly..and it switched on!!!!!! This is great! I wil try the main one later but this wouldnt kick in until 12.30am til07.30am so I cant tell yet.
Now if this has magically resolved itself then great, but I dont want to get too excited. Would there be any reason for it to suddenly start working again for no apparent reason ? (I mean taking into account the hot water was at least used up earlier). Am I going clinically insane? I thought I dont want to come home from the hospital and find a problem when im not really going to be up to dealing with it. Vert bizarre.. I dont know much about these things but hoping for reassurance that the gods of the water heaters have been looking after me :0)

 

[Murdochcat]

What make of controller / switch is it?

If you are going into hospital just make sure it’s switched off so you can’t waste money if it switches on

 

[amosbrown1]

'Backersafe' is the name thats on the round thing (if thats what you mean- excuse my lack of technical knowledge). Yes I will definitely make sure the switches are off when Im in hospital

 

[Murdochcat]

'Backersafe' is the name thats on the round thing (if thats what you mean- excuse my lack of technical knowledge). Yes I will definitely make sure the switches are off when Im in hospital

Photo of the device with the switches on it ?

 

[JohnD]

If the supply is E7, it is likely to turn on and off according to time of day. Usually on round about midnight and off round about 7am.

The overnight electricity is usually much cheaper than the daytime rate.

The booster supply is usually available during the day, at the higher price.

What colour is your cylinder? (This is not a joke)

 

[amosbrown1]

My cylinder is Greeny blue. Yeah the booster wasnt switching on all day. The night time one usually works until 7.30am, but cut out sooner..Normally i would think this is because there is now the full amount of hot water..but.i had a bath about 6.30 am..normally the overnight (cheaper one) starts working again after ive used that much hot water..but wouldnt kick in again even though my overnight one runs til 7.30am..i will see if the overnight one starts working again tonight . perhaps it was just because there was a lot of hot water anyway afterall. Im used to the booster working again as soon as any amount of hot water is used up..but maybe it doesnt always work in such an exact way.. These things baffle me

 

[JohnD]

The green is a fairly modern insulation, it will not lose much heat. Even if you leave it switched on all day, it will not use much electricity because it will already be hot, unless you use up the hot water. If you away for a week or more you will save a bit by turning it off.

The booster element is usually at the top. The top stays hot longest becsuse the hot water ruses when you use it up, so will not come o until you have used up almost all the hot water. The night time element heats almost the entire cylinder, and is usually at the bottom of the cylinder.

 

[ericmark]

OK, we have now a little more info, seems you have two immersion heaters, one, the bottom one, will likely connect to the off-peak, and the top one, likely to some sort of boost switch.

There are many ways to do this, a timer like this

can allow you to select, but there are also some very clever devices like this

which I don't think will be the case with you, but we call it Economy 7, but that is only the tariff, the way we get that power varies a lot, sometimes we have two completely independent supplies, and other times you have a timer which decides when each element is supplied.

On another thread, we see showing a timer top left, which clearly works the relay to the left of the RCD, that works in this case three circuits which don't even come from the same RCD. So what we need is to know how yours works, smart meter, tele-switch, what?

What have you got to test with? An immersion heater can take hours to heat the tank, even a pen tester,

can help, you know power to cable in seconds rather than hours, I don't like pen testers so not saying rush out and buy one, but give us an idea what you have to test with.

 

[JohnW2]

If the supply is E7 .... The overnight electricity is usually much cheaper than the daytime rate.

Used to be. The day/night difference has been becoming increasing small over the past decade or so.

Once upon a time, my night rate was only about one-third of the day rate. Now, it's closer to 75% of the day rate.

 

[JohnD]

Used to be. The day/night difference has been becoming increasing small over the past decade or so.

Once upon a time, my night rate was only about one-third of the day rate. Now, it's closer to 75% of the day rate.

Buy an electric car.

Electric vehicle energy tariffs - EV charging tariffs - British Gas

Reduce the cost of charging your EV at home with our electric vehicle energy tariffs and take advantage of off-peak pricing and smart charging.

www.britishgas.co.uk

 

[JohnW2]

Buy an electric car.

Much as it's not something I like to think about, I think it's extremely unlikely that the savings in electricity cost over the reminder of my life would tot up to the capital outlay - so if I bought an EV I would probably be perpetually worse off for the rest of my life than I would have been if I hadn't bought it.

However, who is paying for/subsidising this, or are the suppliers just accepting a loss of profit, in the hope that it increases the volume of their sales? The supplier presumably has to pay the same for night-time electricity whether it is used to chare EWVs or used for anything else?

What I don't understand is why governments have not yet found a way to recover the revenue they are progressively losing as EV usage increases, hence petrol/diesel sales (and the fuel excise duty thereon) is progressively reducing. That duty is, I think, something like 50% on petrol and diesel, so they surely need to somehow apply a similar duty/tax to 'electric fuel' used for EVs? I imagine that would have to be done on a 'mileage tax' for use of road vehicles, but that would presumably require the widespread deployment of technology - in which case they really need 'to get started'

 

[JohnD]

However, who is paying for/subsidising this, or are the suppliers just accepting a loss of profit, in the hope that it increases the volume of their sales? The supplier presumably has to pay the same for night-time electricity whether it is used to chare EWVs or used for anything else?

The wholesale price is set dynamically, by bid and offer, it's much much less than the punters pay. It used to be published in half hour lots, I don't know a source for it now.

The nighttime demand is low, so every extra pounds worth they can sell is an extra pound towards the CEO's next yacht.

I see we're currently getting about a third of supply from our windmills and nukes, at no additional variable cost, 10% from French nukes and 5% from Norway, I expect they're anxious to shift whatever they can for whatever it will fetch.

Sadly we're burning gas for nearly 40% of supply.

The night tariffs are presumably gauged at average cost plus profit. Some nights are much windier than today, and not so cold, so demand lower.

G. B. National Grid status

www.gridwatch.templar.co.uk

 

[JohnD]

See if you can work out highest and lowest wholesale prices per kWh
(Source: OFGEM)

 

[JohnD]

Here's a more current graph

(Source: Elexon)

Is it around 12p per kWh or have I got it wrong?

Long ago when I worked in the biz I remember it being 3p.

 

[AndyPRK]

JohnW2

At the end of 2024 my E7 rates were
Night 12p
Day 30p approx.

Eon standard
Obviously it depends which region you are in.

Slill a good saving to heat water at night as I did the calcs.