boil a kettle it'll cost you less for small amounts of water.
- Thread starter steveo3002
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steveo3002
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I use one of these (got a battery in it) to come on at 2am and off at 4am to take advantage of the dirt-cheap offpeak rate.
Looking at the breakdown from the smart meter, it's more than paid for itself - I was often switching the immersion on and forgetting about it.
CED Axiom IMT7E Digital 7 Day Surface Electronic Time Switch 16A (2A) | DIY at B&Q
General purpose electronic time switch, ideal for controlling immersion heaters and similarwww.diy.com
so you rely on the battery to keep it going when not on off peak ?
MoreWellie
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Definitely a timer as I put the immersion one day at christmas because of all the showers and forgot to turn it off until I read the meter at the end of Jan 
Buy the best timer you can find as mine only didn't have one as the previous one melted and I needed the immersion quickly so I temporarily bypassed it
Buy the best timer you can find as mine only didn't have one as the previous one melted and I needed the immersion quickly so I temporarily bypassed it
Gareth J
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If you hear it clicking on/off quite regularly through the night, it's possibly due to poor convection around the element rather than significant heat loss.
If it's heat loss, the money would be better invested in a tank jacket and pipework lagging. As well as lowering the tank stat to the minimum you can get away with before worrying about legionnaire's or not having enough hot water.
Then, yes, minimising the time spent at hot temperature will reduce losses. You could install a 3kW coil next time too, if wiring can handle it, to further reduce heating time required (most are ~2.6kW).
It's all marginal gains though and anything you save in winter will also have to be replaced via another heating source.
If it's heat loss, the money would be better invested in a tank jacket and pipework lagging. As well as lowering the tank stat to the minimum you can get away with before worrying about legionnaire's or not having enough hot water.
Then, yes, minimising the time spent at hot temperature will reduce losses. You could install a 3kW coil next time too, if wiring can handle it, to further reduce heating time required (most are ~2.6kW).
It's all marginal gains though and anything you save in winter will also have to be replaced via another heating source.
Farside
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No, the item is fed from the mains full-time, but the battery only steps in when power fails (up to 150 hours according to the bumph).
Although yes, I see what you mean - the battery would cover the mains-off situation from your off-peak meter.
steveo3002
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is it my only option then? bit concerned the battery is more temporary use and might kill it sharpish
Farside
Badly Welded Man
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Just wire to the ordinary mains as a simple timer, controlling a relay for the off-peak immersion.
No worries about the battery then.
not done it yet
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Especially if using gas!!
not done it yet
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A 3kW immersion heater would raise about 130 litres of water by about 40 degrees Celsius over a period of 2 hours.
Relying on an electric immersion heater can be costly, over time, by the need for a hot water cylinder replacement - if on a very hard-water supply. Longer heating elements with lower wattage are better because they may avoid heating the water (in contact with the element) sufficiently to convert temporary hardness to limescale.
A water softener might even be advisable for supplies with high temporary hardness. Heating to the minimum temperature required is best (avoiding legionella, of course, if the HWC is gravity-fed) unless on a soft water or permanent hardness supply.
Most don’t give these things any thought - and likely not even after paying a plumber/heating engineer to replace the cylinder at regular intervals.
Buy an electric car and get on an EV tariff. Octopus Go is currently 9.5p/kWh for 4 or 5 hours each night.
Octopus Intelligent is even cheaper (after the initial investment for the charger, or withn an appropriate compliant BEV).
Relying on an electric immersion heater can be costly, over time, by the need for a hot water cylinder replacement - if on a very hard-water supply. Longer heating elements with lower wattage are better because they may avoid heating the water (in contact with the element) sufficiently to convert temporary hardness to limescale.
A water softener might even be advisable for supplies with high temporary hardness. Heating to the minimum temperature required is best (avoiding legionella, of course, if the HWC is gravity-fed) unless on a soft water or permanent hardness supply.
Most don’t give these things any thought - and likely not even after paying a plumber/heating engineer to replace the cylinder at regular intervals.
Buy an electric car and get on an EV tariff. Octopus Go is currently 9.5p/kWh for 4 or 5 hours each night.
Octopus Intelligent is even cheaper (after the initial investment for the charger, or withn an appropriate compliant BEV).
BarrieJ
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I use an electric kettle for washing up water and 40 mins off peak (dedicated Immersion heater timer) for showers. In winter I keep a large kettle on the solid fuel stove, if it's not boiling I can use the water in the electric kettle and it soon will be.
brightspark
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yep it takes a minute and a few gallons of water to get it to the sink hot
gaz1
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theres a few things involved with emersion heaters
what type of tank you have
the placement of the element
do have a long element (top down)
your usage of the water ( sink, bath-basin )
the newer models only lose 2 degrees per hour stainless steel tanks are better
so with that in mind its your usage sink or bath use whilst a bath will use up half to full water in the tank
element top down longer ones for the bath to heat lower in the tank
elements in the side low element will heat for a bath full
when to turn on last hour of econ 7 in the morning should be enough to run all day with sink - basin usage
bath is twice a day one in economy morning mode the other for when you get home
what type of tank you have
the placement of the element
do have a long element (top down)
your usage of the water ( sink, bath-basin )
the newer models only lose 2 degrees per hour stainless steel tanks are better
so with that in mind its your usage sink or bath use whilst a bath will use up half to full water in the tank
element top down longer ones for the bath to heat lower in the tank
elements in the side low element will heat for a bath full
when to turn on last hour of econ 7 in the morning should be enough to run all day with sink - basin usage
bath is twice a day one in economy morning mode the other for when you get home
