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    • MM333
    • By MM333 3rd Jan 18, 8:01 PM
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    MM333
    Electromax efficiency question
    • #1
    • 3rd Jan 18, 8:01 PM
    Electromax efficiency question 3rd Jan 18 at 8:01 PM
    Hi all,

    I own an electromax electric boiler.
    According to its datasheet It has "99.8% boiler efficiency and integrated economy controller"
    However further down, in the same document there is:
    Seasonal space heating energy efficiency class D
    Seasonal space heating energy efficiency (%) 37

    My question is, out of every 1 kwh input, how much heating (in kwh) is produced ?

    Thanks.
Page 1
    • matelodave
    • By matelodave 3rd Jan 18, 8:40 PM
    • 3,590 Posts
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    matelodave
    • #2
    • 3rd Jan 18, 8:40 PM
    • #2
    • 3rd Jan 18, 8:40 PM
    As the elctromax has an immersion heater then every kwh will produce 1kw of heat into the water.
    However, some heat will be lost due to radiatation and some due to convection and some due to conduction.
    Love makes the world go round - beer make it go round even faster
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    • MM333
    • By MM333 3rd Jan 18, 8:47 PM
    • 8 Posts
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    MM333
    • #3
    • 3rd Jan 18, 8:47 PM
    • #3
    • 3rd Jan 18, 8:47 PM
    What is "Seasonal space heating energy efficiency" ? and why is rated D if it is 99.8% efficient ?
    • matelodave
    • By matelodave 3rd Jan 18, 9:46 PM
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    matelodave
    • #4
    • 3rd Jan 18, 9:46 PM
    • #4
    • 3rd Jan 18, 9:46 PM
    THe electromax is a flow boiler so 100% of the energy gets transferred to the water unlike gas or oil where a percentage of the energy goes out through the flue. However as it's a heating system there are other inefficiencies in the system, like the pumps, temperature control and heat losses.
    Have a look at all this to see if you can chew the bones out of it
    https://ec.europa.eu/energy/sites/ener/files/documents/GuidelinesSpaceWaterHeaters_FINAL.pdf

    As it's a flow boiler it uses electricity whilst it's heating, ie it cannot store energy except that which is in the hot water cylinder so it can't take full advantage of off peak electricity. It's probably one of the most expensive ways you can get to heat your home
    Love makes the world go round - beer make it go round even faster
    Look after our planet - it's the only one with beer
    • MM333
    • By MM333 3rd Jan 18, 11:13 PM
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    MM333
    • #5
    • 3rd Jan 18, 11:13 PM
    • #5
    • 3rd Jan 18, 11:13 PM
    I am looking to replace it. What do you recommend ? There is no gas network where I live.
    • matelodave
    • By matelodave 4th Jan 18, 8:02 AM
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    matelodave
    • #6
    • 4th Jan 18, 8:02 AM
    • #6
    • 4th Jan 18, 8:02 AM
    Your options are Oil, LPG, Biomas, a heatpump or electric storage heaters.

    Oil and LPG require an outside tank to store the fuel and you have to have it delivered by tanker. You'll also need to flue for the exhaust and a condensate drain

    Biomass will require you to have enough space in the dry to store the pellets and it will need a flue, not sure if they have a condensate drain

    A heatpump is another option but needs carefull design of the system to get the best out of one - you cant just bung it onto your existing system and hope it works. You need to understand how they work and how to set them up properly. I've got one and it works but the system was properly designed and I've tweaked it to suit us as they are differnt to a conventional boiler.

    The other alternative is electric storage heaters to replace your wet system.

    You need to do some homework and get a few quotes but I'd guess that oil is probably the best option if you want to use your existing radiators and plumbing and you've got space for a tank.
    Last edited by matelodave; 04-01-2018 at 8:11 AM.
    Love makes the world go round - beer make it go round even faster
    Look after our planet - it's the only one with beer
    • Mister G
    • By Mister G 4th Jan 18, 11:13 AM
    • 587 Posts
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    Mister G
    • #7
    • 4th Jan 18, 11:13 AM
    • #7
    • 4th Jan 18, 11:13 AM
    Don't rule out LPG. The boilers are cheaper than oil boilers and are simpler to maintain. The gas tank is supplied by the gas supplier so you save on the cost of that too. At current LPG prices of 30ppl it is very comparable to oil.

    The only downside is that you are locked into a 2 year contract with a single supplier.

    The other upsides are that it's cleaner and a bit harder to steal than oil!
    • J B
    • By J B 4th Jan 18, 9:54 PM
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    J B
    • #8
    • 4th Jan 18, 9:54 PM
    • #8
    • 4th Jan 18, 9:54 PM
    The only downside is that you are locked into a 2 year contract with a single supplier.
    Originally posted by Mister G
    Not forgetting that the suppliers of LPG have often been referred to as 'highwaymen' or other terms for thieves .......... allegedly!
    • MM333
    • By MM333 5th Jan 18, 1:03 AM
    • 8 Posts
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    MM333
    • #9
    • 5th Jan 18, 1:03 AM
    • #9
    • 5th Jan 18, 1:03 AM
    How much would I save by switching to oil for example ?
    FYI: in december I consumed 1462 kWh and in September 516 kWh
    • Mister G
    • By Mister G 5th Jan 18, 11:39 AM
    • 587 Posts
    • 351 Thanks
    Mister G
    Not forgetting that the suppliers of LPG have often been referred to as 'highwaymen' or other terms for thieves .......... allegedly!
    Originally posted by J B
    Indeed so! I started with LPG back in 1982 with a small local independent as my supplier. He got taken over by Calor and the price ended up going through the roof.

    When the ability to switch after 2 years came in, I found another local independent, who I have been with for the past 7 years. At 30ppl it's very comparable to oil.
    • matelodave
    • By matelodave 5th Jan 18, 12:33 PM
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    matelodave
    How much would I save by switching to oil for example ?
    FYI: in december I consumed 1462 kWh and in September 516 kWh
    Originally posted by MM333
    1 litre of lpg = 6.9kwh @ 30p/l* = 4.35p/kwh
    1 litre of oil = 10.7kwh @ 30p/l* = 2.80p/kw

    so assuming around 85% efficiency for an oil or gas boiler your 1462kwh would increase to around 1700kwh = 246ltr (73.80 at 30p/l*) for LPG or 169 ltr (50.70 at 30p/l*) for oil.

    *you need to check how much oil or lpg would be where you live as I haven't got a clue but the sums are easy.
    See here how the average price of heating oil has fluctuated over time - anywhere between 60p/l to 26p/l https://www.boilerjuice.com/heating-oil-prices/


    dunno what you pay for your leccy and whether you've got an E7, E10 or some other complex tariff but I guess that a proportion of your consumption is for cooking, washing, lighting, TV and other stuff so you'd need to take that into consideration.

    My air source heatpump works out at around 4-4.5p/kwh based on my 11.83p/kwh electric only tariff. There's no real advantage for me to have an E7 tariff as the machine is only idling overnight and is in use most of the day.
    Last edited by matelodave; 05-01-2018 at 1:05 PM.
    Love makes the world go round - beer make it go round even faster
    Look after our planet - it's the only one with beer
    • Mister G
    • By Mister G 5th Jan 18, 4:06 PM
    • 587 Posts
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    Mister G
    Not particularly defending LPG, but I think that you'll find the current Kerosene 28 price is nearer 50ppl at present, rather than the 30ppl used.

    This would make the calculations look a little different.
    • matelodave
    • By matelodave 5th Jan 18, 4:24 PM
    • 3,590 Posts
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    matelodave
    Not particularly defending LPG, but I think that you'll find the current Kerosene 28 price is nearer 50ppl at present, rather than the 30ppl used.

    This would make the calculations look a little different.
    Originally posted by Mister G
    as I said, I haven't a clue about the price of oil or lpg or even mains gas come to that, that's why I put in the disclaimer and suggested that the OP did his/her/their own sums using relevant info.
    Love makes the world go round - beer make it go round even faster
    Look after our planet - it's the only one with beer
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