How Efficent is an Overnight Immersion Heater?

westv

Just wondering. The place I'm in has gas heating but the hot water is an immersion heater that runs between 11pm and 7am. In other places I've had just the normal set up where gas is used for both the heating and the water. I've normally found that having the hot water on for about 3/4 hour in the morning and about an hour in the evening was fine. The current set up is on a lot longer but I know that it will only be actually heating the water at certain times. Is this a particulalrly efficent method of heating water compared to how I had it before? I'm not currently on E7 and the rest of my electricity use is daytime.

penrhyn

The Immersion heater will be 100% efficient in heating your water, however as you are using day rate electricity it will cost you 3-4 times more than using gas.

Make sure your tank is well lagged and the tank thermostat is set around 60 degrees, no more.

dogshome

Hi westv - As you say, it's a very odd set-up.
How well the H/water tank is insulated? - If it's a modern type where the whole tank is covered with a layer of foam insulation, it's pretty efficient ( I heat half a tank in the morning and it's still warm enough for a shower in the early evening ), If you have a family, a couple of one hour bursts a day should cover it. There is absolutely no need for it to be on for 8 hours at a stretch
The timer you have is probably adjustable but only activates once each 24 hrs, so try to adjust it to the hour you need hot water for your life style

But if it's an older tank with just a jacket like flower petals that you strap on, it will lose heat quite quickly, so really the only way to use it is to put it on for half an hour before each person wants to use hot water.
All the best

westv

Thanks for the replies.
As far as I can see the lagging is good. As regards the timing, again as far as I can see, the only adjustment available is a boost button to swtch it on at anytime between 7am and 11pm.

st999

I don't have an immersion heater in my hot water tank and I pay 60p a day to heat my water by gas.

Stan

westv

What I might do is have it switched on for 1 overnight run, then switch it off and then see how long the hot water lasts. I only really use it for a shower for myself each day.

dogshome

Hi again westv - From your later post referring to "A boost Button", it would seem that this Immersion Tank is something that was installed when your house had ECO 7 heating.
Whilst it seems that the Storage radiators have been done away with, do you stll have an ECO 7 meter set up?

Sometimes in the circumstances of Gas CH being installed, the Elec. supplier will leave the E7 meters in place, but add the two readings together to charge your power as though you had a Standard Meter, whilst others will change the meter, but if the provider doesn't know you have gas CH, they will continue to charge an ECO 7 tariff - Is there both a DAY RATE and NIGHT RATE listed on your bills?

ECO 7 Night power is cheap, but on the Day use, you pay appx. 50% more on the Prime units and 11% on the Secondary units, than a standard meter.
However, if you still do have ECO 7 and no storage radiators, you could win slightly on cost by heating the water and running the washing machine and dishwasher overnight - but whatever you do, DON'T USE THE DAYTIME HOTWATER BOOST BUTTON
All the best

westv

As far as I can tell the house has always had gas radiators and electric water heating. All very strange if you ask me! I have just found a splurge that lists the timings for the immersion and that says a total of 10 hours:-

5 hours during night 12pm-7am
3 hours afternoon 1pm-4:30pm
2 hours evening 5:30pm-10pm

Sound like E10 to me. Does that still exist?!! Not sure if those timings are still valid or not. I suppose there's no reason to think they have changed.

The two meter readings are added together on the bill.

westv

And if by magic I have just received a bill via the net!
After a very rough calculation it appears the overnight heat up is costing me 91p a day for the first 21 days of the quarter and 35p a day thereafter. If those timings above are correct then I would assume the day rate for heating the water is the same.

Swipe

If it were ecomony 7/10 there would be daytime and night time rates listed. If not, you may as well just put the immersion heater on by the boost button as and when you need it rather than overnight. That's what I do but I only have a single element in mine but check to see if you have two (one at the bottom and one at the top).

isie1980

Hi,
I live in a flat with electrics only and have an economy 7 system. My tank has 2 elements - one timed and one for the 1 hour boost. The timed element is broken so I put the boost on for an hour when I go to bed and it provides enough hot water for 2 fairly quick showers in the morning. I put the boost on again before leaving for work and I have enough hot water for my evening washing up. The room heaters are rarely used and my bill is about £30 a month for electric and shows two rates.
Does this help?

Found this post whilst searching for some advice - I'm going to rent my flat out soon so need to get the timed element on the tank working. Do I need an electrician for this or a plumber? Any idea of cost? The timer works, its the element that's gone.
Cheers