Leaving immersion on 24/7 vs putting it on when you need it

civis_liberalis · 16-02-2012 01:03AM #1

This can't be more efficient, can it?

A stubborn house-mate wouldn't be told otherwise and to shut him up I just gave in.

This may be a difficult question to answer as there are probably a huge variety of different boilers in different states of repair and other variables I wouldn't understand :rolleyes:... but if anyone has any idea, I'd be very interested to hear your thoughts on it.

For a person who used to go on about the electricity usage of the other tenants, he seemed to be worse than anybody, never mind the immersion situation.

whizbang · 16-02-2012 10:19PM

My mother outlaw does this.
swears that after 40 years of watching electricity bill, its cheaper to leave it on 24/7.
she has the tank wrapped to 3 times its size in blankets though.

civis_liberalis · 17-02-2012 12:02AM

I can't imagine it is better than switching it on in the evening when somebody is actually in the house.

whizbang · 17-02-2012 12:38AM

If peak demand electricity pricing comes along, it will be a winner

RealExpert · 06-03-2012 12:31AM

Leave it on 24/7 and when the bill comes give it to your stubborn house-mate he will then realise there is another way!

TPM · 06-03-2012 01:05AM

The idea is:
if the cylinder is well insulated once it heats up the stat turns it off,
due to the good insulation the water temperature only drops slowly,
and when the stat does eventually cut in the immersion only has to "top up" the water temperature and so is only on for a short time.
Versus
turning on and off the immersion and heating the cylinder from cold each time with the immersion running flat out.

At the end of the day there is probably little difference if the immersion is on for a few hours in the morning and evening versus being on all day

nacimroc · 06-03-2012 10:43AM

We have proved it makes no difference. We leave it on 24/7. We have tried it both ways over the last few years and there is absolutely no difference in cost whatsoever.

We tried it on constant for 2 months, off for 2 and done this a few times to check meterage to be sure. My wife insists on it, I wanted it off and after all the arguing and testing it makes almost no difference.

(Based on: Our tank is lagged, 1 bath and 1 shower in an evening only. Heating on for 3 hours every evening)

TPM · 06-03-2012 11:27AM

nacimroc wrote: »

We have proved it makes no difference. We leave it on 24/7. We have tried it both ways over the last few years and there is absolutely no difference in cost whatsoever.

We tried it on constant for 2 months, off for 2 and done this a few times to check meterage to be sure. My wife insists on it, I wanted it off and after all the arguing and testing it makes almost no difference.

(Based on: Our tank is lagged, 1 bath and 1 shower in an evening only. Heating on for 3 hours every evening)

that proves you tank is well lagged and your stat is working properly too:)

With the "immersion" on all the time you are only replacing heat loss and/or water usage and in a well insulated tank the heat loss will be minimal

nacimroc · 06-03-2012 03:36PM

TPM wrote: »

With the "immersion" on all the time you are only replacing heat loss and/or water usage and in a well insulated tank the heat loss will be minimal

All you professionals can probably confirm that it may be largely based on the time the heating is on, being the same as the time we have the baths/showers? Most of the work is done by the boiler and the remaining few degrees would be picked up by the electricity I reckon.

TPM · 06-03-2012 04:06PM

A average insulated tank/cylinder should have a heat loss of less than 2kw per 24 hr.

So once heated up it should use less than 2 units per day to maintain the set temperature(excluding water usage) if left on all day.

on the other hand if it is turned off the temperature wont drop drastically so it wont take a lot to heat it back up again.

Leaving immersion on 24/7 vs putting it on when you need it

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