UKC

So our gas boiler had a service today and we were told it is on its last legs. 

Replacing with gas seems like an irresponsible thing to do these days, but electricity prices don't make an electric boiler an attractive option. 

We are thinking of looking into heat pumps if there are still grants available, but I am dubious as to their effectiveness in a house of the age and build of ours without a lot of work.

So, what strikes the best balance of green Vs cost (both cost of installation and running cost)? Is replacing with gas again as bad as we think?

It can't be an expensive replacement, we don't have anything spare at the moment. 

Obviously, we will make good use of jackets etc anyway. 

In reply to girlymonkey:

I would go for one more gas.  In 10-15 years' time (typical economic life of one) alternatives will be more easily and cheaply available.

In reply to girlymonkey:

I was first told our old boiler "needed replacing really soon" a decade ago. This summer (when 38 years old)  a service engineer spotted rust on the outer box and condemned it (fair enough) but misdiagnosed the cause. We went on checkatrade and got a few full inspections, and found the real problem as part of several quotes and went with the best sounding engineering advice and got a replacement for the boiler, retaining our 'system' (plus various other central heating fixes, including replacing a leaking valve that rusted the boiler case) for well under £2k. The big players were quoting around triple that just for the boiler. To me it was a sensible stop-gap as other solutions were just too expensive or impractical for now. 

On being green don't forget gas generates most of the electricity we use on those cloudy windless and very cold winter days when we need a boiler most.

In reply to Offwidth:

While it might be true its still the most economically attractive option, saying it's more green because gas makes most of the leccy "on cloudy windless very cold winter days" totally ignores the fact that you use heating most days in winter and that most days a lot is produced by renewables, with the mix only progressing towards being *more* renewable over the next 10-15 years. The grid isn't static. 

In reply to Offwidth:

To be fair the only purpose of getting a quote from British Gas is to get a ceiling price, not to go with them!

That and a free asbestos check on my back board.

In reply to girlymonkey:

If we assume gas is 10p per KWH @ 90% efficient then that's 11p per KWH of heat

Electric at the moment is say 35 p per KWH, and the efficiency of a air source heat pump can be anywhere between 200% and 400%. I'm enclined to believe that during winter when we really need a lot of heat, it's probably closer to the 200% mark, but lets be kind and assume an average of 300%. That's then 12p per KWH.

So running costs can be comparable. Of course if you just go for an electric boiler you're stuck at closer to 35p per KWH, but you can get the electric storage boilers and and EV type tarrif where it's cheaper to charge at night, but I couldn't seem to get a straigh answer on what the off peak tariff is from a quick google. Could be something to look into.

All in all, gas is the cheapest to install, an probably still the cheapest to run. Modern ones are often dual fuel and can also run on hydrogen which could offer green options for the future.

In reply to girlymonkey:

We had to make a similar decision a couple of years ago, I really wanted to go with a heat pump as anything else seemed like a step in the wrong direction.

Our house is stone built, poorly insulated and has high ceilings (3ish metre).  We had a heat pump installer come and look, they said it would work but we would need two of the heat pump units which was going to be very expensive.  Speaking to other people (who didn't have anything to sell) they doubted that a heat pump would actually even get the house warm.  We went with an oil boiler.

I think you're right to be dubious on fitting one at your house.  If you can get an insulation/energy survey that would give you better information to make a decision from. 

In reply to Alasdair Fulton:

Where did I say it's more green?  It's a trade-off between cost and partly improved greeness... renewables are over 40% now of UK generation but gas still provides nearly 40% and sets the marginal rates that fixes the cost per electricity unit. There are many options in life to be greener without opting for a currently expensive heat pump system. 

In reply to Offwidth:

If using electric heating, it does beg the question on whether we should only be heating our homes outside of peak usage times regardless of what tariff we are on.

Peak electric times will almost always be mainly gas generated electric as it's a cheap responsive way to react to the demand.

Offpeak we're relying on the the grid base-load which I assume is mainly renewables and nuclear and maybe biomass and only gas on particularly still days.

In reply to montyjohn:

Stop assuming.

https://gridwatch.co.uk/

In reply to girlymonkey:

I just had a quote for air source for a standard size 3 bed house, 11,500. Grant of 5000 available. Do not fit one in an uninsulated house, we did this and were spending 500 a month on electricity before the price rises last winter. I've upgraded my 1900 solid wall property, it now has a cavity and wall insulation, concrete insulated floor with underfloor heating and insulated roof - up to scratch for air source but I can't afford it. Electric boilers are very expensive. I'd stick with gas.

In reply to montyjohn:

Most people using electric heating will have storage heaters which do exactly that (crap though they are), though I suspect mass EV adoption will result in an end to Economy 7 etc because the load will be much more spread as most cars will be plugged in overnight.

In reply to girlymonkey:

I'm in same situation. Existing boiler gas more or less had it, might limp through winter but needs replacing.

I'm going for another gas boiler. Mainly as alternatives (i.e. heat pump) are expensive, and fitting experience seems to be fairly limited at the moment. Plus it means ripping out all the other radiators/heating system, and replacing with underfloor or oversized rads.   

I'd like market to mature a bit more before taking the plunge. 

In reply to Phil79:

I forgot to mention that was another reason I got a new replacement boiler. In my quote I was promised a new boiler and all the other system repairs in a week, where it was vague when I could get a new heat pump (uncertain system availability and the planning for much longer labour time slots).

It's a bigger risk right now than in previous years if facing a potential breakdown.

In reply to girlymonkey:

I've just been through this process, I live in a small terrace with no room for a ASHP and couldn't afford to completely retrofit the heating and hot water in my house to another system anyway, which for most properties are pretty considerable. I take some consolation in the fact my new boiler is vastly more efficient than the last.

I have a friend in a similar situation and their going with a new gas boiler but external cladding on the house to minimize use.

In reply to Longsufferingropeholder:

Cheers....you beat me too it. It was maybe understandable how ignorant most people were, about how reliant we had become on gas generation, before this energy emergency. It's much harder to see an excuse for people posting on threads like this now, with such weird misunderstandings (about there usually being no gas use off-peak.... when in fact gas generation is pretty much always 24/7).

In reply to girlymonkey:

An alternative if you can't do airsource: https://tepeo.com/ 

It's essentially a central storage heater, a bit thermal battery that you charge up for cheap at night and it just plugs into your existing central heating system.

In reply to girlymonkey:

Hmm.... Discovered early this morning (what I kind of knew already) that my old gas combi boiler is going to be a lot of work (so money) to work on to the point it's not economical. So the decision of this thread was mine today.

Friday I'm getting another gas combi fitted. I'm in a small 1930s mid terrace and no spare space so another gas combi it will be.

At least because a new one won't have clagged up heat exchangers I can expect (who knows, 30%?) more efficiency that my current one. But agreed continuing gas for heating and hot water isn't the "future"

In reply to Sam W:

Our house doesn't sound quite as bad as yours for this. It's a late 70s Wimpy type house. So it's not absolutely awful, but not up to new build standards. I think we would at least need new windows for starters to make it work. New windows have been on the wish list for a while, but no money for them just now, so certainly none once we have replaced the boiler!!

In reply to girlymonkey:

I'd still go gas and then invest some of the difference you would have paid if you'd gone ASHP on insulation and preparations for a potential move to ASHP in when he boiler dies. Consider replacing any radiators that are small or would be too small if you were running heating at a lower flow temperature. This is an easy job for anyone with fairly basic DIY plumbing skills and is fairly cheap.

If you are hot on the DIY, as many people on here are, consider whether you could sort some of your windows yourself. It's not rocket science, you can buy bespoke units online (what most small companies do anyway) and I think you only need FENSA registration or building control sign off for just renewing windows.

In reply to girlymonkey:

I have an ASHP installed in a 40 year old house. If you have any questions, happy to answer.

In reply to Offwidth:

This is a useful graph.  Yes, gas is ever present (and is going to be for a long time to come if we don't sort our act out) but the percentage it represents drops significantly in the night time lull:

https://electricityinfo.org/fuel-mix-last-24-hours/

Of course, it's much better to burn a kWh of gas in a CCGT and then use that energy in a 250-300% efficient heat pump, than it is to use it in a 90% efficient domestic boiler, even taking transmission losses into account.

In reply to gethin_allen:

One thing that has made me hesitate about ASHP is that our radiators are plumbed in using microbore pipework, and I wondered whether that would need changing out as part of a switch to ASHP.  It occurred to me that, with the lower flow temperature available from ASHP, the last thing you'd need would be pipework that impedes the flow as well.  I could probably find various opinions by digging around online but I just wondered whether you, or anyone else on this thread, could give an authoritative answer to this?

In reply to Jamie Wakeham:

It would be lovely if heat pumps were cheaper, with an army of heating engineers easily stocked up and ready to instal immediately and our radiator systems all compatible and our housing stock capable of retaining the heat to make such a system practical. In the meantime people are often forced to compromise.

In the graph you posted gas was still a good bit over half of the generation in the 'night time lull' (although that varies a lot, as per the gridwatch link above).

In reply to Offwidth:

Re-reading your post, you mention you got a boiler fixed and other work for about £2k and the replacement cost would have been triple that? Is there something unusual or remarkable about the boiler? Just for perspective I'm looking to have existing combi replaced with another gas combi 30Kw (Ideal) for £1,750 all in and I'm in London! so I am very confused by your figures. Just asking out of total nosiness....

In reply to CantClimbTom:

My new boiler cost about £3.8k all in, possible a bit on the pricey side as it was replacing a condensing one so needed some new pipework. I think this wasnt unusually high though, I think you are lucky with that cost!

In reply to CantClimbTom:

Sorry if I wasn't clear... I paid for a replacement modern boiler for an old (condemned) boiler (plus quite a bit of extra work).

In reply to girlymonkey:

What is actually wrong with it?

Our combi is circa 30 years old and there is no problem getting parts for it.

In reply to Martin W:

I can't offer any authority on the issue but I have heard it mentioned that microbore pipes aren't ideal.

In reply to girlymonkey:

Just to throw a curve ball in to the mix.

We moved two doors down the road (three years ago) from a rented to owned home, both identical 1950's semi detached bungalows, both have modern double glazed windows same aspect etc etc

Rented place had modern gas combi boiler with central heating but poorly insulated, and electric shower.

New place has upgraded insulation (cavity wall and roof space) , but mostly electric, with a multifuel stove in one room only, storage heaters, hot water tank etc no electric shower. The stove only gets used during the coldest months and in three winters we've only used around 20 x 20kg bags of coal and one load of firewood.

Surprisingly the electric property is much cheaper to run than the gas heated place. 

Note, we virtually never run the storage heaters, I've even taken two out completely, teenage son has never used the electric heater in his room,. We almost always have the back door /windows open due to dog wandering in and out. 

I think a big part of it is, being acclimatised to a cooler house (cant stress this enough). When we go to other, closed up, centrally heated houses it feels awful, lethargic etc. 

In reply to artif:

What sort of temperature are you running at?

In reply to artif:

I find having an open fire is the best way to stay warm. Not necessarily due to the heat it gives off, but from how warm I feel after chopping wood. 

Tried roping the wife in but she's not interested.

So for those who struggle to acclimatise, if you can, doing more exercise is a great alternative.

In reply to girlymonkey:

I take it you've checked for funding etc. on home energy Scotland?  https://homeenergyscotland-advice.est.org.uk/fundingfinder/Schemes

Might we worth seeing about an interest free loan for new double glazing, or insulation etc. 

In reply to Neil Williams:

No idea, I guess whatever the ambient temp outside is, plus or minus a bit, the insulation keeps it a bit cooler in the summer and a bit warmer in the winter.

Even the neighbours comment, if they see me wearing trousers, as I'm usually in shorts year round walking the dog etc. We didn't even change from the lightweight summer duvet during last winter, we did close the bedroom window a few times though.

In reply to Offwidth:

Of course.  To be fair the govt is giving you £5k to install one, which does help with the initial outlay.  

Yep.  But in general, the grid is less gas (and coal) dependent overnight.  As a result the carbon intensity is, usually, at a low between midnight and 5am.

In reply to girlymonkey:

Having just gone through the same situation you have, unless you're house is well insulated then gas is unfortunately the only cost sensible solution.

I would have preferred a heat pump, but can't justify the upfront cost and although I have insulated the house to the max it's still not enough for heat pump at the moment.

Electric boilers are a solution, but with electricity prices are way to expensive to run. Might be more effective and fun just to burn the money 

In reply to Alasdair Fulton:

I sent them an email yesterday to see if they can advise on best options for us. I wondered if they have someone who can actually come and see our house and give suggestions. I will look at their funding options too.

In reply to girlymonkey:

If I was replacing ours right now I'd go for another gas one, I think in 20 years when it's on its way out we'll be in a much better place to switch to an alternative as right now I think the tech is still in the earlier adopter stage. 

For me in a 4-bed, 300 year old-ish ex farmhouse which has just had all new floors down the cost/effectiveness of a heat pump doesn't add up for us yet. 

In the next 5 years or so we will need the roof replaced so we might invest in solar panels as we have a large expanse of south-facing roof so it might make sense, that may then make electric powered heating of some form or another more viable I don't know.

In reply to artif:

Our house is always kept cool. I still don't close the upstairs windows at this time of year. However, it is nice to have the option to warm it up when people come over who do need it warmer. I sit at home in winter with hat, jacket and duvet on me! 😂

In reply to Philip:

What upgrades did you do to radiators etc? Did you install underfloor heating? How hard and costly was it to make the house suitable for it?

In reply to ian caton:

I didn't get the full story from the plumber, I was at work and my husband spoke with him. 

He is someone who has done a lot of work for us and my parents over the years and we trust him. He said it's fine while we keep it low, but if we put it higher he said there is a real risk of carbon monoxide poisoning. I don't know more than that.

In reply to girlymonkey:

Some friends of ours had an off-grid hydrocarbon (Oil I think) boiler swapped for a heat-pump. I'd guess 90's/00's house so reasonable insulation, maybe cavity fill, but nothing out of the ordinary. Double radiators replaced with triples, singles with doubles but nothing major. They love it and say it's significantly cut their heating bills.

Might be worth getting a quote or three with some estimates as to running costs.

jk

In reply to girlymonkey:

As others have said there is no feasible alternative atm for those on a budget.

If I was in your situation I would go for a last gas combi boiler. If we do get a sensible energy plan any time soon I would hope it would concentrate initially on reducing/eventually eliminating gas used for electricity generation, as that is something the government can realistically get involved in, and there are solutions, with more coming on stream.

Replacing gas for CH/HW in people homes will be more difficult with our housing stock and dealing with millions of awkwardly different homes rather than several large scale projects, so most of us will be on gas for the foreseeable. Really need to start planning now though so let's hope the current government get kicked out soon.

In reply to ian caton:

my combi won't keep the pressure and hot water only works for short time. aircraft noises. radiator heating ok. any ideas? (heat exchanger?)

are used boilers worth looking at?

In reply to magma:

If it’s gas one, you would need to check the legality. I was told by a Corgi Gas engineer, quite a few years ago now, that it was illegal for them to fit any secondhand gas appliances.

Further, when I had a perfectly functioning gas hob that I wanted removed, I suggested that it could be given away and he said he was required to decommission it so it couldn’t be re used as part of the removal.

In reply to magma:

If it won't keep pressure then you need to find the leak. If it's a new issue then it's probably something that either moves or is exposed and has been bumped. Try wiping down all you pipes, valves and radiators you can see with a handful of dry blue roll.

Can't help with the second issue, you could always take out a cheap insurance package on it and hope if fails properly.

I very much doubt you'd find a good second hand boiler or anyone wanting to fit one. Why would someone have a perfectly good boiler removed? it's not like a car where people want to show off, people get new boilers when the old ones break.

In reply to magma:

Diaphragm in expansion vessel failed maybe - try pressing the inflation valve - if water comes out then the vessel needs replacing

In reply to magma:

Losing pressure in a combi could be a number of things including a cracked heat exchanger. But maybe more common is dripping out of the overpressure valve, do you have a small pipe from the boiler that goes outdoors and is open to the air (i.e. can vent pressure/water in emergency) -- is it damp, has it been dripping?

If you are losing pressure due to a dripping relief valve that is an easy fix (for a qualified heating engineer). And the low pressure *might* be the cause of the boiler making a lot of kettle noises and going into lockout when heating water.

Get someone qualified to look at it

If you hunt about you can get a cheap/nasty boiler like a Biasa Advance including flue kit and delivery for just shy of £700 but you're better off spending a little more and get an Ideal for about 1k as it will probably last longer and be more repairable. Swapping out old with new might?? be £500 of work. prices vary a lot so shop around. Only use qualified and reputable gas safe heating engineers to do the work, unless you want to risk gas or carbon monoxide or something in your home!

In reply to girlymonkey:

At the point of installation we had a 25 yo house with cavity wall from build. I insulated the loft. We removed the coal fire / back boiler + microbore pipes and storage heaters.

We had the house thermally modelled as part of the installation. I chose radiators with 2.5x the output you would have for 70 C water. No underfloor. I used Stelrad radiators - one of them is 2.2m triple convector. Having kids, one thing I love is the radiators run about 35C and the hot water is 45C - very little risk of burning yourself.

I have since put floor insulation as we renovated each room, and used triple glazing.

Costs in 2014 for ASHP + Solar PV + Solar thermal + all plumbing/rads was £22k. With F-i-T and RHI it paid back in about 5 years.

In reply to CantClimbTom:

relief pipe has been dripping but only after forgetting once to turn of the repressurisation valve- pressure increased to max and dripping started. pressure fell to normal after an hour and down to nil after 24h.

thanks for advice. will see what engineer says..

In reply to magma:

When we had our boiler changed I got them to put in an additional larger expansion vessel next to the boiler fir not much extra cost. The small ones crammed into boiler casings are not really adequate for larger systems, can run out of headroom resulting in relief valve discharge and can fail prematurely and expensively

In reply to magma:

That makes me think a bit of crud has got into the relief valve and is preventing it closing fully.

Have you checked the fill valves? They tend to be cheap and nasty, could be one of those has started leaking when the boiler went over pressure. Might be dripping from there.

In reply to Ridge:

In the past I've had trouble with both... a dripping filler overpressured the system which in turn caused the relief valve to drip and they are prone to getting crud in them and then dripping - and losing pressure, over a day or so to go to zero

Not sure whether to share my relief that I now have reliable hot water (and so reliable shower) due to the new boiler I had fitted today. Hoping that mentioning won't be insensitive to OP, but if you can get your boiler replaced, a new one will work so much better than an old one that I had (especially if like mine the heat exchangers were clagged up, as part of its many problems)

In reply to girlymonkey:

I'd miss her dreadfully 😘

In reply to girlymonkey:

You could reach out to an eco-biased heating services company (eg: HeatGeek, Your Energy Your Way, Ecobubl) with some specs about your house. They can do the heat loss calcs and advise on the suitability of a heat pump or alternative. If you are able to take advantage of local government funding as well as the £5k grant it might be more viable than you think. Really no way to give a definitive answer without measuring rads, pipes, walls, insulation levels...

Alternatives exist, but will likely be out of budget. (tepeo mentioned above - useful as I assume you are on an EV tariff)

I would probably nurse the existing boiler instead of try to replace it. Insulating whatever you can will be cheaper and quicker than any heating device install, and allow you to turn the flow temp down on the boiler. If you can turn the flow temp down as far as possible it will stress less, condense more, and save gas/cost. The insulation you add over time will make it easier to fit a heat pump/other when the time comes

In reply to girlymonkey:we’ve been told our gas boiler is on its last legs every year for the last 20. Mainly due to British Gas carrying a reduced level of spares for that model and threatening not to be able to fix it if it goes wrong. All spares are available elsewhere on the web if necessary but it hasn’t been / they’re  just scaremongering 

In reply to George Killaspy:

This will also tell you if heat pump is viable.  The info is already out there - If a heat pump running efficiently chucks water out at 40degrees, then if you can insulate enough and increase rad size enough to keep your house warm with a boiler outputting at 40degrees then you know you're good to change to a heat pump doing exactly the same thing.

In reply to magma:

Speaking from experience, one of the following has happened:-

1)The pressure vessel needs pumping up with air again. If it's currently full of incompressible water, when you fill the system there is no gas to buffer it, and the tiniest loss of water will cause the pressure to fall rapidly.  If this is the case it will take hardly any water to re-pressurise the system.

2) you've a leak in a heat exchanger.

3) You've a leak elsewhere in the system - damaged pipe, leaking joint, rad or fitting.

Once you've proven it's not (1) I don't know how (2) or (3) are proven - I guess the boiler engineer can isolate the boiler and pressurise it to see if it leaks internally.

In reply to George Killaspy:

According to the heating engineer on Friday, for a bog standard condensing combi his rule-of-thumb is set the heating to 56C and only turn it above that if it can't make your house warm enough (very cold snap, insufficient rads etc) for the reasons you stated above 

To be complete... there is a benefit to be considered, for replacing rather than nursing, that an elderly boiler will likely have the heat exchangers a bit clogged up and the pick-a-number-out-of-thin-air figure is to expect a new condensing combi to be 20% less gas use than a 9+ year old one.  20% of our current gas prices are not insignificant

In reply to montyjohn:

This is very obvious in my household - My elderly Dad literally spends all day sat reading the paper / doing crosswords / watching telly and has the heating cranked well up in the lounge and his room. My young son is charging round in shorts and T-shirt all day and is drenched in sweat at night even with no heating in his room and the window open. The rest of us are somewhere in between with minimal heating in our rooms and windows open.  I read somewhere once that the average human outputs 1kW of heat, and that means 'passivhaus' standards of low energy use are relatively easy to attain in well-occupied, well-insulated buildings.

In reply to jiminy483:

Surely you knew what was going to happen? You knew the spend on FF heating beforehand, thus knew how many kW you were putting into the house, and thus were able to work out the cost of getting the same number of kW out of your heat pump? Were you misled?

In reply to Toerag:

Kids are odd creatures though.

Mine (two and five) don't get cold in the house. First thing in the morning, I'm putting layers on straight away. The kids don't seem to care. Don't want to wear a jumper. Fine by me.

Before going to school, we have a session of "no, you need to wear a jumper and a coat, it's cold outside". I win of course, eventually, and then, as soon as we step outside they're moaning it's too cold.

In reply to Toerag:

You sure that wasn't 100 Watts, not 1 kW?

In reply to CantClimbTom:

Yup, that’s my layman’s conclusion. I’ve mine set to 55°C for most of the year after experimenting and researching on the web. I only put it up in winter to 60° and then 65° in the coldest spells or it can’t get up to room temp set.
Does mean that it takes a longer time to get the home up to temp by using lower settings and some may not want to wait as long. Too high though in my home and the residual heat in the radiators can put the room temp anything up to 1.5°C more than the thermostat was set at depending on time of year.

When my heating engineer install the boiler he said 70°-75°C all year!! Mine is a modulating one so seems happy to either click on and off, or run more continuously at the minimal gas usage it can operate at, once the home is up to the min temp I’ve set thermostat to.

In reply to Toerag:

This was a project I was doing with my Mum, it was a big detached 4 bed house that she now lives in. She heard about the grant and suggested we get one as her friend had one fitted and said it was cheaper to run. At the time I literally didn't know air source pumps existed and I just went along with it. It wasn't until the first winter that we realised we had a problem. I got the attic up to current regs but my Mum was far more excited about the new extension than insulating the walls and floors, 50g over budget by this point so they never got done. 

The house needs external insulation for the heat pump to work well, maybe she'll get it done at some point. We've since fitted a log burner so the plan this winter is to use the heating much less.

I think air source is great for modern well insulated houses but for uninsulated leaky old houses they just run constantly on the coldest days.