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Immersion heating costs - is an elec element more expensive than gas for 30 mins ??

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  • 15-07-2018 4:35pm
    #1
    worded
    Registered Users Posts: 4,545 ✭✭✭


    Is it very similar cost if the gas boiler is modern to elec cost

    For my own reasons I prefer to use Elec in the summer to heat water.

    Thanks


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    #2
    Sleeper12
    Registered Users Posts: 16,927 ✭✭✭✭Sleeper12


    worded wrote:
    For my own reasons I prefer to use Elec in the summer to heat water.


    Gas is much cheaper to heat water. Possibly as much as half the cost of electricity


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    #3
    Victor
    Registered Users Posts: 78,290 ✭✭✭✭Victor


    It somewhat depends on both circumstance and the amount of water.


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    #4
    worded
    Registered Users Posts: 4,545 ✭✭✭worded


    Victor wrote: »
    It somewhat depends on both circumstance and the amount of water.

    The Emerson is fully insulated

    It’s a difficult one to guage ....

    How much does it cost to run gas heating water for 30 mins and elec for 30 mins presuming that both bring the water to the same desired heat ?

    I hear the elec has an advantage for efficiency as it’s element is in the water it’s heating where as gas has to pump the water to the target tank and there is loss of heat on the way there ...


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    #5
    Wearb
    Moderators, Home & Garden Moderators Posts: 6,232 Mod ✭✭✭✭Wearb


    Anyway that you look at it gas will be the cheaper option, unless there is something wrong with the installation such as not having a DHW zone.

    Please follow site and charter rules. "Resistance is futile"



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    #6
    Sleeper12
    Registered Users Posts: 16,927 ✭✭✭✭Sleeper12


    worded wrote:
    I hear the elec has an advantage for efficiency as it’s element is in the water it’s heating where as gas has to pump the water to the target tank and there is loss of heat on the way there ...


    Electric is definitely the most efficient but you need to compare how much a kw of energy is in gas and electricity. You should find gas works out a lot cheaper to heat water than electricity.


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    #7
    John.G
    Registered Users Posts: 3,474 ✭✭✭John.G


    worded wrote: »
    The Emerson is fully insulated

    It’s a difficult one to guage ....

    How much does it cost to run gas heating water for 30 mins and elec for 30 mins presuming that both bring the water to the same desired heat ?

    I hear the elec has an advantage for efficiency as it’s element is in the water it’s heating where as gas has to pump the water to the target tank and there is loss of heat on the way there ...

    The sink element of a dual immersion will heat say 40 litres of water to 40C in that 30 mins and consume about 1.3 Kwh (of electricity) at 100% efficiency but a gas boiler (depending on cylinder & coil size) would only take around 18 mins and consume around 1.9 Kwh (of gas) at a boiler&system efficiency of 70%, so gas is apparently cheaper, I think I calculated a few years ago that the boiler&system efficiency would have to be as low as 40% to equal full cost electric but see below.
    Of course a gas boiler can't heat "only" 40 litres and will normally heat say 150 litres so this would take ~ 7.0 Kwh of gas but if your daily hot water consumption is only 40 litres then theoretically there is 3 to 4 days of hot water available but cylinder losses will take another ~ 1.5Kwh/day so the "real" gas boiler consumption per 40 litres will be 4.0 Kwh/day,
    Cost: assuming electric @ €0.18/Kwh, electric heating cost, (0.18*1.3), €0.23/day and assuming gas @ €0.07/Kwh, gas heating cost, (0.07*4), €0.28/day.

    So ONLY if one is using ~ 40 litres of hot water/day then electric heating is a good and cheaper? option.


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    #8
    worded
    Registered Users Posts: 4,545 ✭✭✭worded


    Thanks for all the help and suggestions


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    #9
    Jennehy
    Banned (with Prison Access) Posts: 155 ✭✭Jennehy


    Sleeper12 wrote: »
    Electric is definitely the most efficient but you need to compare how much a kw of energy is in gas and electricity. You should find gas works out a lot cheaper to heat water than electricity.

    Electricity is 100% efficient. Perharps the op has night saver.


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    #10
    Sleeper12
    Registered Users Posts: 16,927 ✭✭✭✭Sleeper12


    Jennehy wrote:
    Electricity is 100% efficient. Perharps the op has night saver.


    Night saver, if you already have it would definitely be the cheapest option. Problem with night saver is the standing charge is so expensive. You need to have an electric vehicle or storage heating for it to be worth while getting in.

    Another cheap way to heat water is a combi boiler, again if you already have one installed.


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    #11
    colm_mcm
    Registered Users Posts: 73,392 ✭✭✭✭colm_mcm


    Isn’t the night saver meter only like €4 a month extra or something?


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    #12
    Sleeper12
    Registered Users Posts: 16,927 ✭✭✭✭Sleeper12


    colm_mcm wrote:
    Isn’t the night saver meter only like €4 a month extra or something?


    About 60 euro per year more so around 5 per month. ESB say that for you to benefit from the night saver rate you will need to use over 25 percent of your electricity needs at the night rate. Not many homes can do this without charging an EV or storage heating. I suppose its down to the individual. If you have a big cylinder & a big immersion the night saver rate might work out for you in the summer. You wouldn't use it as much in the winter when the heating is on


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    #13
    John.G
    Registered Users Posts: 3,474 ✭✭✭John.G


    Sleeper12 wrote: »
    Night saver, if you already have it would definitely be the cheapest option. Problem with night saver is the standing charge is so expensive. You need to have an electric vehicle or storage heating for it to be worth while getting in.

    Another cheap way to heat water is a combi boiler, again if you already have one installed.

    A combi boiler gives instant hot water at probably up to 90% efficiency so the cost of producing 1 kwh of hot water is around (£0.07/90%) £0.078/Kwh, depending on the cost of gas. If the household requires around 150 Litres of hot water at 60C (daily) then a normal condensing boiler&system will not be too far off this 90% so similar hot water costs at only about 40% of producing hot water from full cost electricity. So yes, definitely IMO, "You need to have an electric vehicle or storage heating for it to be worth while getting in" (night saver) and you must only heat the hot water on night saver rates.
    Full cost electric water heating does make sense in the summer months but only if using very small quantities of hot water which I think was the OP's original query.


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    #14
    John.G
    Registered Users Posts: 3,474 ✭✭✭John.G


    Sleeper12 wrote: »
    About 60 euro per year more so around 5 per month. ESB say that for you to benefit from the night saver rate you will need to use over 25 percent of your electricity needs at the night rate. Not many homes can do this without charging an EV or storage heating. I suppose its down to the individual. If you have a big cylinder & a big immersion the night saver rate might work out for you in the summer. You wouldn't use it as much in the winter when the heating is on

    I am looking at the night saver charges a bit more closely now as a friend is looking at installing all electric space & water heating in a small house without any form of central heating at present.
    Another extra cost (with night saver) is that the dayrate/Kwh is 5% to 7% higher than for full cost electricity.
    The night saver standing charge would appear to be ~ €40 to €55 extra when I look at a few suppliers on Bonkers.ie.


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    #15
    Sleeper12
    Registered Users Posts: 16,927 ✭✭✭✭Sleeper12


    John.G wrote: »
    I am looking at the night saver charges a bit more closely now as a friend is looking at installing all electric space & water heating in a small house without any form of central heating at present.
    Another extra cost (with night saver) is that the dayrate/Kwh is 5% to 7% higher than for full cost electricity.
    The night saver standing charge would appear to be ~ €40 to €55 extra when I look at a few suppliers on Bonkers.ie.


    I looked into this myself a few months ago too. Well the wife rang our supplier rather than me. She said immersion on for two hours, dishwasher & washing machine set to come on at night. Supplier said we'd be mad to swap to night rate without EV or storage heating.


    Long term I'm thinking PV panels. I have the cash to do it now but everyone is saying it's still to early to get in on PV & I'm not a fan on solar thermal.


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    #16
    John.G
    Registered Users Posts: 3,474 ✭✭✭John.G


    Sleeper12 wrote: »
    I looked into this myself a few months ago too. Well the wife rang our supplier rather than me. She said immersion on for two hours, dishwasher & washing machine set to come on at night. Supplier said we'd be mad to swap to night rate without EV or storage heating.


    Long term I'm thinking PV panels. I have the cash to do it now but everyone is saying it's still to early to get in on PV & I'm not a fan on solar thermal.

    A bit off topic but I reckon that if you use 7300 Kwh/annum (20 Kwh/night) to charge the EV battery and assuming that you dont have night saver just now then it will cost 11.66c/Kwh (to charge the battery) based on Electric ireland as your supplier, by shopping around, you can probably reduce this to ~ 10 to 10.5c/kwh. Electricity prices are increasing by ~ 6% from next month


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