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How to calculate cost of Electric CH Boiler

Discussion in 'Electrics UK' started by KevinRussell, 26 Sep 2021.

  1. KevinRussell

    KevinRussell

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    Hi

    Hyporthetical question: If I replaced my Gas CH Boiler with an Electric CH Boiler, how much would my Electric bill be?

    How do I calculate, using my existing gas usage, how much the equivalent Electric usage would cost?

    Any pointers would be great,
    Kevin
     
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  3. flameport

    flameport

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    kWh of gas you currently use, multiplied by the cost of electricity per kWh.
    The result will typically 4 or 5 times greater than you pay for gas.

    Don't buy one. It will be a very expensive mistake, and if you have a combi boiler that heats water on demand, the hot water performance of an electric effort will be 2 to 4 times worse than the gas one.

    Electric boilers are a total bust in every way possible.
     
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  4. JohnW2

    JohnW2

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    .. in many ways, certainly - yet the plan is apparently for gas boilers to be 'phased out' - and quite quickly if the government had its way!

    Kind Regards, John
     
  5. flameport

    flameport

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    Electric boilers are not the replacement for gas and oil.

    Heat pumps are - but they also require other significant alterations such as much larger radiators or underfloor heating.
     
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  6. RandomGrinch

    RandomGrinch

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    I thought your answer to my earlier question about alternatives to gas, was most eloquent and might be worth a look by the OP.

    https://www.diynot.com/diy/threads/any-thoughts-on-the-future-of-heating.578015/
     
  7. ericmark

    ericmark

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    During the second world war the UK government realised we would need to rebuild once over and things like the 13 amp plug were developed to assist the rebuild, the whole idea was we would use electric for heating, however it has to date not transpired, we have in other words seen it all before, and realise it is some ones pipe dream.

    The Ronan Point collapse has resulted in high rise flats being all electric, and the heat pump has resulted in some success, but what has happened since the second world war is we have embraced central heating, and in the main central heating is integral to our homes.

    However heating unused rooms clearly costs, and there has been a move to better control, the main thing about better control is heating speed, and much depends on the building, if your trip home from work takes ½ hour and you can heat the first rooms to be occupied in ½ hour then you could use geofencing to turn on heating, electric has some advantages in that inferred is very fast heating, but also very hard to control, the water circulation method is slow, using hot air is faster, and with electric no need to be ducted it can be de-centralised.

    However that does not help with heat pumps, and the main problem is we want far higher output radiators to be able to heat the water to lower temperatures and heat rooms faster, so the only option seems to be fan assisted radiators, I has an old Myson in old house, there was a slight noise, but modern ivector myson radiators use variable speed fans which alter speed rather than water throughput to vary output.

    Having all radiators piped in series would work well with ivector radiators, or a boiler where the return water temperature does not matter, however our gas boilers modulate (turn down output) as the return water temperature increases, this works well with TRV controls on radiators, but not so good where there is no restriction on water flow, an odd kick space heater in kitchen OK, but all radiators turned to fan assisted would require re-piping.

    Then we look at cost, the cost of fan assisted radiators is rather high, control raises the cost even further, building management is made for large buildings, but not really for the private house, the standard EvoHome, Wiser, or other smart control system designed for domestic is not really going to work altering fan speeds.

    I think in fullness of time we will have fan assisted radiators, one advantage is they can heat and cool, so connected to a heat pump they can heat in winter and cool in summer, but as yet the control system for domestic is simply not made, and the big question is if it can be made at a reasonable cost?

    I went to brother-in-laws old house, really good system, the solar panels, wood burning fire, LPG boiler, all heated a water heat store, and the store then heated the house as required, however there was something like 100 gallons of water in the store, up stairs as safety needs thermo syphon in case of power failure for wood burner, so a very well reinforced floor on airing cupboard, and the system put around £25k on price of house, it could have in real terms only be done with a new build, when he moved to stone cottage he did consider it, as did work well, but it was not practical.

    So we have to consider the build of the home, my last home was open plan, worked well if all rooms heated, no real option to only heat rooms being used, this house has internal doors, so using programmable TRV heads we can heat rooms when required, but radiators are too small for a rapid reheat, the fan assisted would likely work well, as oil fired so return water temperature not important.

    But central heating is an integral part of the homes design, or at least it should be, and to try an alter is not easy, yes we can re-purpose items, my wood burning flue is now the exhaust for the AC. But that is no where near as good as an AC designed to be integral with home.

    So it needs some careful thought, every home is different, after living in an open plan house for 25 years, moving to a house with doors has required a re-think on how to heat, what worked with one does not work with the other, also life style, as retired we want heating 24/7, the whole idea of geofencing is rather pointless for us, in fact most people who go out to work, return as set times as simple timed temperature change often works better.
     
  8. JohnW2

    JohnW2

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    True, but do you think that large-scale 'retrofitting' heat pumps would ever be a viable policy?

    Kind Regards, John
     
  9. ericmark

    ericmark

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    Is a heat pump classed as a boiler? Lets face it, domestic boilers only boil the water when faulty, the boilers at work make super heated steam, and are real boilers, but once one uses a word which described the original unit as the name for the unit that replaces it, be it a transformer, ballast, or boiler, where do you stop?

    The government seems to love ambiguity, need to notify if you change a consumer unit, nothing about notifying if a distribution unit is changed, seems to be designed from the outset so people can get around the law.

    We had it with central heating zones, many seem to think a zone needs a hard wired zone valve, however the councils seem to say in their websites that using TRV's creates zones, seems it was never intended that zone valves are used. Which makes sense, as other than EPH you can't get any controllers which will work with OpenTherm and zone valves, EPH seems to be only one that makes a thermostat with a master/slave set-up.

    But if we are going to power the home with electric only then we will need huge upgrades to the national grid, on the 19th December 2008 Abergeirw a small village of 9 properties was connected to the national grid, it was started in 1935, so going by pass performance most of us will be dead long before we go 100% electric.

    The government is clearly only paying lip service to renewable, or the grants for solar panels would not have been stopped, they it seems are just playing to the crowd and have no real intentions of really going full renewable.
     
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  11. flameport

    flameport

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    It will be eventually. Probably not for a decade or two - new builds and major refurbishments will be the uses before then.
    However gas will be going away, and heat pumps are the only viable large scale replacement.

    Electric boilers can never work as they apply a very high load when in operation - exactly what can't be provided by ageing power networks, and also not by electricity stored in local batteries unless those batteries are massive.
    Stored hot water and distributing the heating load over the whole day with the ability to switch it off when electricity availability is low is essential.
     
  12. JohnW2

    JohnW2

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    Who cares - that's surely just a semantic issue, isn't it? We're talking about the means of heating 'spaces' and water, regardless of the words used.
    Again, semantics. TRVs obviously do create 'zones', in fact to a greater extent, and more flexibly (not just 'on/off'), than do 'zone valves'. Just as with electrical switches, all that matters is that it is 'in the circuit'- whether or not a switch is physically close to the load is irrelevant.
    Indeed, but I think we've always known that, sooner or later, that was going to have to happen, since once we run out of ('naturally available') gas to distribute, I doubt that we will manufacture and distribute (via pipes) any other sort of 'gas fuel'. Heat pumps are I suppose part of the ultimate answer, in that they are 'local' and don't require any distribution. Reduction in energy requirements is also a major part of that 'ultimate answer', but there is a limit to how far that can go.

    Kind Regards, John
     
    Last edited: 27 Sep 2021
  13. JohnW2

    JohnW2

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    I suppose that's probably true.
    Again, essentially all true. However, the escalation of EV charging will presumably considerably change/distort the patterns of demand at different times of the day, such that the periods of lowest demand may become 'the daylight hours' (which, ironically, are the only times when real-time use of solar power is possible!).

    Kind Regards, John
     
  14. KevinRussell

    KevinRussell

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    Wow - some comprehensive answers - great information. I agree that Ground Source Heat Pumps are possibly the future.
    Thanks @flameport for the rather obvious :oops: calculation - and yes, it's quite an expensive conversion. I won't be making the change anytime soon.

    Kevin
     
    Last edited: 27 Sep 2021
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  15. flameport

    flameport

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    Ground source is only viable if you have a substantial amount of land available, and are prepared to excavate most of it to a depth of at least 1m.
    Theoretically possible to DIY, but simply not an option for most.

    Air source heat pumps are more likely.
     
  16. JohnW2

    JohnW2

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    Indeed - and, as I impolied, and for those same reasons you mention, probably not very viable option as 'retrofit', even if not DIYed?
    True, but I have to say that I have difficulty in getting my head around the physics of that!

    Admittedly in the opposite direction from that which we currently worry about, wouldn't very widespread deployment of air-source heat pumps result in a degree of 'climate change'?

    Kind Regards, John
     
  17. plugwash

    plugwash

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    Some heat is moved from outside to inside, this adds to the heat generated by the heat pump to make the heat that heats the house.

    The issue with heat pumps is that they get less efficient at higher delta-T, this is why ground source is usually more efficient than air source and why a lower flow temperature is better than a higher one.

    Well the heat pumped into the house by the heat pump is going to leak back out over time as will the heat from the electricity consumed by the heat pump, so the house as a whole will still be a net heat source.

    In any case my understanding is that direct releases of heat by humans are negligable in climate change terms, it's the indirect effects that make the big difference.
     
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