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We're getting some major renovation/extension work done and as part of that we are going to be replacing our boiler.
We currently have an Ideal Mexico Super 3 floor standing gas boiler and it's chuffing massive! Takes up a full height cupboard in the kitchen for the boiler itself, then another full height cupboard in the upstairs hall for the cold water storage tank and hot water cylinder. Then another header tank in the loft!
It's also fairly old and crap, so we're planning to rip it all out and start afresh.
We want something with on-demand hot water (rather than storage) so some kind of large combi I guess?
We're replacing the gas hob with induction, so if we stick with gas then the boiler will be the only thing using it. Seems a waste paying a standing charge just for that.
So the question is: are leccy boilers up to the task or should we stick with gas?
(For reference, once the reno is done the house will be 4 bed, 2 bathrooms + wc, so a decent boiler capacity but not ridiculous)
Electricity is more expensive than gas, and stuff like an immersion to heat a water tank uses a lot of energy, so a leccy boiler for heating and hot water must cost a fortune to run, no?
Yeah, your gas heating and hot water will be the biggest user by far, probably an order of magnitude more than what you're using for cooking. TBH, its's the gas cooker that wouldn't be worth having a standing charge for!
I have an electric house and use PA11 gas bottles for cooking, they generally last 4-6 months. For heating and hot water they'd not even last a month per bottle.
Unless you've got an absolutely massive roof, covered in solar panels, and electrical storage, stick with a gas boiler for now.
(Unless you decide to go all out GSHP/ASHP/Solar/etc then you'll need to get a proper look at the whole thing.)
i put a combi in 12 years ago .
next time round ill be going back to storage for future proofing.
along side that ill be putting solar thermal on the roof above my solar PV and routing all that into the tank........
ill have a small boiler for heating driven by what ever makes sense at the time .... maybe even heatpump will be useful to me by then.....
and electric combi sounds mental. - imagine an electric shower(and more) on for 2-3 hours every day...the wheels on the meter will spin like turbo.
Electricity is more expensive than gas
Yes absolutely. My current rates are:
Standing Charge per day:
Gas: 27.2160p
Leccy: 48.6464p
Unit rate per kWh:
Gas: 7.2240p
Leccy: 27.090p
My current projected spending pre-reno (from supplier) works out at £1707pa for Gas and £2024pa for Leccy.
Dropping gas means ditching ~£100 a year standing charge, but obviously increasing the amount of leccy used (possibly to a point where adding solar becomes economical).
stuff like an immersion to heat a water tank uses a lot of energy
That's really my question I guess: has the technology in leccy boilers got to a point where they are more efficient or are they still basically big kettles.
Too many variables.
A GSHP installation is potentially cheaper to run than gas, ASHP less likely to be cheaper - but with PV, maybe.
If you have the land and the means GSHP might make sense, but you’d need someone who knows their stuff to look at your property.
See also solar thermal, and hybridisation of heating systems.
That’s really my question I guess: has the technology in leccy boilers got to a point where they are more efficient or are they still basically big kettles.
Big, crappy, furred up kettles...
Dropping gas means ditching ~£100 a year standing charge
Genuinely, you'll use this in a week running heating and hot water by (non ASHP/GSHP) electricity
but obviously increasing the amount of leccy used (possibly to a point where adding solar becomes economical).
So, because you'll be spending more on leccy, you can then spend even more on getting some solar to offset the leccy? That sounds like 'interesting' maths.
Serious answer - gas boiler, HW storage, and solar to heat the HW in the storage when possible sounds like the best bet by far.
If you have the land and the means GSHP might make sense
We have the land but builder and architect have both said that they don't think it is worth it.
Solar on the roof is more of a possibility. We have an electric car to run as well.
Morning all,
Efficiency is not something that will be a significant variable between heating water by gas or electricity. The amount of energy required to raise the temperature of water is a constant so same energy required.
Using the rates above it will cost almost four times as much to heat with electricity as gas using a 'simple' boiler stlye heating system, no technology will change this.
To reduce energy use and thus cost for electricity you will need to use some form of Heat Pump as they generate more energy output then they consume, typically up to 3:1.
My dad had electric Ch. His monthly bill was over £1k. It was a big house, but still...
So, because you’ll be spending more on leccy, you can then spend even more on getting some solar to offset the leccy? That sounds like ‘interesting’ maths.
Probably 😁 my (possibly slightly backwards) thinking was that solar PV doesn't really pay for itself if you don't use much leccy.
But you are using a lot of leccy...
possibly slightly backwards
Definitely entirely backwards, I'm afraid chap 🙂
Hmmm... okay seems everyone is pretty keen on sticking with gas as the more economical solution, which begs the question why is the government looking to ban gas boilers in new builds by 2025??
Are they expecting everyone to use ground source and heat pumps?
which begs the question why is the government looking to ban gas boilers in new builds by 2025??
Who knows, environmental targets i guess. Unfortunately, they need a viable alternative first. They don't really have one yet.
Are they expecting everyone to use ground source and heat pumps?
Amongst other things, i suspect it will be a disaster, and astronomically expensive to both build/install and run.
It needs a MASSIVE infrastructure change and things like communal heating/Solar PV/Solar thermal etc to become the norm.
IGM is correct, if you are considering replacing a gas boiler with straight electrical heaters (immersion for hot water, with electric radiators), don't, you will increase your energy bill by approx 3-400%. If you are considering a heat pump it might be viable, it can be a great way to bring electrical power usage down compared to electric heaters, but realise that heat pumps need to be sized correctly and to make it work efficiently in most homes you need to spend a significant amount to add insulation and improve air tightness in the home. I wouldn't rule it out altogeather but you need to educate yourself about the pitfalls because there internet is full of stories about poorly executed installations with the heat pumps being on 24/7 with huge bills and still resulting in a cold house.
I haven't had either installed but am also planning a large renovation, with the research I've done, I have pretty much decided to invest heavily in making the building envelope as good as I can feasibly manage (adding EWI and increasing air tightness with a membrane internally) within my budget and stick with a gas boiler until I can afford a GSHP in 5-10 years time, by that stage installers will be more experienced and costs should have come down.
1. New houses are supposed to be much better insulated than typical a draughty 1970s 3 bed semi using a gas boiler
2. GSHP use energy to transfer heat, rather than using energy to produce heat so are more efficient.
Whether this all works is another matter.
Don't suppose your old Mexico 3 boiler has a square flue does it?
If so what condition is it in ?
GSHP are relatively stable with ambient temperature if the GS is deep enough. They can also be fairly powerful.
ASHP has had issues on cold days as the AS is both weaker than a GS in the first place and colder. I’m told they are getting better though.
depending on the size of the house I wouldn't be so hasty towards a combi over a tanked system either. Combis are great for small properties, but don't work out any more economical to run than a tanked system (the money saved not keeping an insulated tank of water hot is lost by heating water from 3C -> 50C as it passes through the boiler), and they have several disadvantages (particularly flow rate when filling a bath/having several users at once). A mains pressure tanked system is great for larger properties
GSHP are relatively stable with ambient temperature if the GS is deep enough. They can also be fairly powerful.
Out of interest, could a GSHP be piggy-backed onto an existing borehole for water?
why is the government looking to ban gas boilers in new builds by 2025??
New houses 'should' be well insulated and from the promotional videos I've been watching, far infrared panels will possibly be the preferred source of 'space/room' heating in a house rather than a wet central heating system. 🤔.
The occasional shower and hot water requirements for washing up and making a brew will be managed easily by an heating element. No cylinder storage needed, just a battery bank for storing power from solar.
Combis are great for small properties, but don’t work out any more economical to run than a tanked system
Interesting. Another possibly bad assumption from me.
My thinking was that we like hot water on demand, but heating a huge tank of water just so its always warm when I wash my hands seems daft. We have a leccy shower and will have a dishwasher, washing machine is cold fill, so not sure what else would be needing all that stored hot water?
Baths are a very rare occurrence in our house, though I guess that may be because we currently only have one bathroom. 😁
5lab
Free Memberdepending on the size of the house I wouldn’t be so hasty towards a combi over a tanked system either. Combis are great for small properties, but don’t work out any more economical to run than a tanked system (the money saved not keeping an insulated tank of water hot is lost by heating water from 3C -> 50C as it passes through the boiler), and they have several disadvantages (particularly flow rate when filling a bath/having several users at once). A mains pressure tanked system is great for larger properties
Can you explain that first bit? It's just that it seems unlikely that heating the water and storing it would be more efficient than heating it on demand?
I am watching this with interest. I was thinking about replacing the boiler this year, the last two yearly services I have been advised to nurse it and replace it in summer. Thing is, I don't actually use it to heat the house just for hot water. Small house (double upper it is called in Scotland) fairly well insulated, wood-burner for the main room and plug in heaters to locally heat the small rooms when in use, my energy bills are not large.
Can you even buy a thing that just heats the hot water for the shower etc and get rid of the radiators? They are ugly, make the house too hot and take up way too much space. It is an 1860s four dwelling terrace with thick stone walls.
Can you even buy a thing that just heats the hot water for the shower
Guess you could have a leccy shower and something like a Quooker tap for (very) hot water.
I would be investigating a 120ltr dual fuel dhw tank. 3kw heating overnight on the octopus lowest rate tarif.
Then 28kw boiler for gch and a top up of your dhw if you have guests
You get redundancy if gas or elec goes off for whatever reason.
Octopus 4hr tarif was 6p kwh or so, will be more now.
Use the specific heat capacity of hot water to your advantage
You cam add pv to top up your dhw at amy time to reduce the costs but look ay payback times, can be decades.