Should my water heater be on 24/7??

longwalks1

Recently moved into an old 1930's semi with copper cylinder in the airing cupboard and tanks in the loft (my old flat had a combi boiler = nothing to understand, immediate hot water on tap :j )

Had a fair bit of work done indoors recently including a powerflush as the sludge knackered our CH pump, and a surrey flange fitted to the copper cylinder. Looked in the airing cupboard and the fused switch inside that says 'water heater' was on. I switched it off as I thought it was a type of override feature? Anyway, with it switched off yesterday, no hot water this morning, is this normal?

Please help

big_mortgage

It sounds as if you have just switched off the immersion heater. Do you have your normal heating/ HW on right now?

Ebe_Scrooge

As per the reply from Big Mortgage - most "standard" heating setups have a boiler, and a timer which lets you control the Central Heating and the Hot Water ( you can usually program the 2 independently ). So on a standard day-to-day basis it's the boiler that heats the water, but you also have an immersion heater as a backup in case the boiler fails.


If the boiler is gas or oil fired then it's much cheaper to let the boiler heat the water, rather than the immersion. I would suggest you need to locate your programmer and understand how it works ( if you don't have the user guide then odds on you will find it online by Googling for the make and model number, or else go to the manufacturer's own website ).

Smiley_Dan

Ebe_Scrooge wrote: »

If the boiler is gas or oil fired then it's much cheaper to let the boiler heat the water, rather than the immersion.

There are a number of "buts" to that...

Depends on where the immersion is located.

Depends on whether E7 can be utilised.

benjus

I do keep the water heater on 24/7, but using the gas boiler to heat the water and not the immersion heater (in fact I've never used the immersion heater since buying the place and don't even know if it works).

The main reason I keep it on 24/7 is that we don't have particularly regular schedules and want to have hot water available at any time. However, the cylinder is a modern, heavily insulated one, so I don't think I'm wasting too much energy in doing so. If it was an old-fashioned bare copper cylinder with a bit of lagging loosely tied around it I would probably not take this approach.

girlsmum

how do you control your CH timer? where ever that is you can set the timer to control both HW and CH.
mine only goes on for 1 hour a day between 4-5pm and its enough. if i need extra i just pop in on for an hour, as the water in the tank (if lagged) should stay quite hot, i know mine is still hot in the morning

dominoman

If the tank is well insulated and you are using it several times a day then having it on 24/7 makes sense.

The difference in energy cost between 24/7 and having it switch on and off on a timer will be negligible.

Le_Kirk

The concerning part to me is that the OP switched off the (presumed) immersion heater and then had no hot water following day. This indicates that (as others have suggested) that the programmer is not set to HW at any time or at least not for long enough.

J_B

dominoman wrote: »

If the tank is well insulated and you are using it several times a day then having it on 24/7 makes sense.

The difference in energy cost between 24/7 and having it switch on and off on a timer will be negligible.

You are sadly incorrect with your 'advice' - there's even an article on MSE about it somewhere.

dominoman

J_B wrote: »

You are sadly incorrect with your 'advice' - there's even an article on MSE about it somewhere.

I am *not* incorrect with my advice.

If the tank is well insulated and is being used regularly throughout the day then whether you leave it on a timer or on permanently will make next to no difference, and will be far outweighed by the extra convenience.

As soon as the water is up to temperature the thermostat will stop the hot water heating. The only energy needed will be to keep it topped up to temperature as it slowly loses heat, and that will be minimal.

If the tank were not being used regularly then it would of course not make any sense to keep it heated. But the OP said it was used reguarly. A modern well insulated tank of 100l will lose 0.3-0.4 W/l, so that would be a loss of 40 watts, or 0.96 kwH every 24 hours. Around 14 pence.

If it is being used, say, every 4 hours, and is on a timer to turn it off overnight, the temperature when "off" will drop a little over those 7 hours (someone with more time or maths skills than me could do the calcs) so the heat gradient between the tank and air will be lowered and therefore it may lose 0.3 W/l say rather than 0.4W/l for a short period. Either way the effect on bills will be a few pence per week at the very most.

Far more important than whether your heater on a timer is 1) maximising the insulation, including the pipework leading into and out of the tank and 2) heating using the gas boiler rather than immersion.

HappyMJ

dominoman wrote: »

I am *not* incorrect with my advice.

If the tank is well insulated and is being used regularly throughout the day then whether you leave it on a timer or on permanently will make next to no difference.

As soon as the water is up to temperature the thermostat will stop the hot water heating. The only energy needed will be to keep it topped up to temperature as it slowly loses heat, and that will be minimal.

If the tank were not being used regularly then it would of course not make any sense to keep it heated. But the OP said it was used reguarly. A modern well insulated tank of 100l will lose 0.3-0.4 W/l, so that would be a loss of 40 watts, or 0.96 kwH every 24 hours. Around 14 pence.

If it is being used, say, every 4 hours, and is on a timer to turn it off overnight, the temperature when "off" will drop a little over those 7 hours (someone with more time or maths skills than me could do the calcs) so the heat gradient between the tank and air will be lowered and therefore it may lose 0.3 W/l say rather than 0.4W/l for a short period. Either way the effect on bills will be a few pence per week at the very most.

Far more important than whether your heater on a timer is 1) maximising the insulation, including the pipework leading into and out of the tank and 2) heating using the gas boiler rather than immersion.

You also forgot to mention the utility factor of not having sufficiently hot water an hour after having a bath to be able to hand wash the dishes.

Pedantically you actually are incorrect in that it does cost 1 penny a day more to have the immersion on 24/7 than it does having it on for 3 hours in the morning and 3 hours in the evening.

Although you did say negligible what is the definition of negligible? If it were a penny per day that's £3.65 a year now a not so insignificant amount and no longer negligible.

I'd leave it on 24/7 at a lower temperature so when water is drawn off for a bath the water is immediately reheated ready for use elsewhere. I wouldn't want to have just had a bath then realize there isn't any hot water then have to wait an hour for the cylinder to reheat. I'd just leave the dishes dirty.