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Cheapest way to use the immersion heater

edited 30 November -1 at 12:00AM in Energy
150 replies 307.8K views
1246715

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  • ronerone
    18 posts
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    Defo 1.5KW.

    I've measured it by virtue of making sure nothing is running other than immersion heater and seeing what is consumes over 90mins for that particular part of the day.

    Plus, even if it's thermostatic you can base your measurment of an upper limit of what it would consume if it was driving all the power all the time, your real world would be less, which is no bad thing eh?

    Can't argue with my bill, and I don't have much choice as we can't have gas.
  • CardewCardew
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    rone wrote: »
    Defo 1.5KW.

    I've measured it by virtue of making sure nothing is running other than immersion heater and seeing what is consumes over 90mins for that particular part of the day.

    Plus, even if it's thermostatic you can base your measurment of an upper limit of what it would consume if it was driving all the power all the time, your real world would be less, which is no bad thing eh?

    Can't argue with my bill, and I don't have much choice as we can't have gas.

    That certainly does not mean it is "defo 1.5kW"

    It might only use 2.25kWh over 90 minutes, but if it was 3kW it could be only heating for 45 mins. The average is 1.5kWh consumption for that 90 min 'test'.

    Put it this way. Mine is certainly 3kW. If I leave it on for 24 hours and it uses 2.4kWh that doesn't make it a 0.1kW (100 Watts) heater. It means it has been heating for 0.8 hours in the 24 hour period.

    I suspect if you left it on for 90 mins and during that time were using lots of hot water, you would use a lot more electricity.
  • ronerone
    18 posts
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    Cardew wrote: »
    That certainly does not mean it is "defo 1.5kW"

    I completely understand what you're saying and I take your point but the "defo" bit comes from the fact that I seem to remember metering it.

    In terms of kWh I was able to equate the usage over time to the cost which happened to equal what the meter was reading, hence I gathered - from cold it was consuming 1.5kW for the duration of time it was on.

    Also, 24hrs is a much broader comparison, it doesn't equate to the same average on a 90 minute "from cold" useage which I suspect will be close to full load for most of the time.

    But I will double check, because you've got me questioning myself.
  • CardewCardew
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    If you can get to look at your immersion heater it will have the rating on the top cover.

    The other way to test will be switch it on when water tank is cold, check the meter, and then check again after 20 mins - if it is 3kW it will have used 1 unit.

    I only gave the 24 hr example to illustrate the point.
  • 7Kw or 4Kw?

    I want to fit an immersion heater and the most useful setup would seem to be to have it on a timer. The cheapest route is a plug in timer, which would restrict me to a 3Kw heater. Anything bigger could not be used with a simple plug in timer.

    Is 3Kw worth using? Are they any good?
  • CardewCardew
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    stevemof wrote: »
    7Kw or 4Kw?

    I want to fit an immersion heater and the most useful setup would seem to be to have it on a timer. The cheapest route is a plug in timer, which would restrict me to a 3Kw heater. Anything bigger could not be used with a simple plug in timer.

    Is 3Kw worth using? Are they any good?

    I have never heard of a domestic immersion heater bigger than 3kW and yes they are more than adequate.
  • hi, I am just new to this place. and punched in google and came across this place.

    I have a 2 rate meter and currently we use the gas boiler to heat the hot water and heating, currently everything turns on at night from mobile phone chargers to even the cordless house phones. I just found out the hot water tank also has a electric immersion heater at the top. we have a big house hold.
    would it be effective to use the immersion heater at night or just stick with the boiler. the boiler right now turns on just for two hours to warm up the house a little and give us hot water. but during the hot summertime we only turn our boiler on for hot water only. and of course during winter its on its lowest setting and left on all day long. so If I turned the immersion heater on for the 7 hours during the night would that be better or just stick to the boiler.
  • MagentasueMagentasue
    4.2K posts
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    DINX wrote: »
    hi, I am just new to this place. and punched in google and came across this place.

    I have a 2 rate meter and currently we use the gas boiler to heat the hot water and heating, currently everything turns on at night from mobile phone chargers to even the cordless house phones. I just found out the hot water tank also has a electric immersion heater at the top. we have a big house hold.
    would it be effective to use the immersion heater at night or just stick with the boiler. the boiler right now turns on just for two hours to warm up the house a little and give us hot water. but during the hot summertime we only turn our boiler on for hot water only. and of course during winter its on its lowest setting and left on all day long. so If I turned the immersion heater on for the 7 hours during the night would that be better or just stick to the boiler.

    It would almost certainly be cheaper to use gas to heat your water. Can I ask why your are on Economy 7 if you have gas? On some tariffs you need to be using more than 50% of your electricity at night to make this tariff pay and this is almost impossible to achieve without electric storage heating.
  • reading around other websites they say at least 30% needs to be used during the night. and I average around 29- 31% use during the night. for a 3 bedroom house with 5 people living inside we only spend £25 direct debit and the account is in credit of over £130.

    using the immersion heater would be consider as a waste then?
  • MagentasueMagentasue
    4.2K posts
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    Gas is about a third of the price of electricity. Check on comparison websites - you may be better off on a single rate tariff. There's no fixed percentage that makes it a good idea and, whereas the rule of thumb used to be that you could break even using 25% of electricity off-peak, this is no longer the case. May work for you but worth checking rather than assuming it's still worthwhile.
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