Replacing a mains gas boiler in a very old house – what with?

Main structure is over 600 years old, solid walls with a wooden frame, single glazed (although fairly small) windows, *massive* inglenook fireplace up through the middle of the building (added a couple of hundred years after the house was built – not currently used due to leaks but liner and multifuel stove being fitted shortly), there’s a 1920’s extension – partly wood framed, part brick. It’s in a conservation area and there’s limited scope for internal insulation (the bedrooms are all in the roof so there’s limited opportunity for roof void insulation, walls need to breathe as they’re lime plastered), there’s a gas Aga in the kitchen but it’s not heating water or owt. Heat pumps could only go on a north facing wall.

Everything I’ve read about air or ground source heat pumps says ‘don’t start from here’ as far as the building’s concerned as they just won’t cope – is that a fair assessment? Should we just stick with mains gas?

These green grants of £5k look good hhttps://www.gov.uk/guidance/apply-for-the-green-homes-grant-scheme and we might be able to access them towards the cost of a non fossil fuel boiler or some of the primary insulation things (there’s an uninsulated flat roof on part of the extension, for example).

Anyone recommend a resource or company who look at the house holistically that we can use for advice on what we should do?

All depends on how much additional works you’re prepared to undertake.

If it is just replacing the boiler with minimal disruption then you’re limited. If you’re doing more internal works then that opens up the spec and scope.

Re the new wood burner for example – any scope for a hot water tank higher up and buying a stove with a back boiler to heat said hot water whilst its burning? Water in the tank can then be used for pumped heating circuits and/or for hot water supplies to kitchen, bathrooms etc.

Obviously more initial work, but savings down the line over gas usage.

Heritage House, Pete Ward possibly

He uses a biomass boiler

Any kind of heat pump has a lower output temperature compared to mains gas.
It can work well where you can insulate to the max, remove drafts and install underfloor heating. If you can’t do those, then I’d look elsewhere.
Have you considered biomass (a wood pellet boiler).

Echo the above, ground source is expensive and relies on a big area of floor at a lowish temperature in a well-insulated house. Not suitable for your big badly insulated house then.

Before the green wash get here. Based on what you have another gas boiler but I’d consider not buying it. Sounds like a money pit
That will never be green.

Is the building listed?

I had an oil fired aga with a boiler and a big Coalbrookdale wood burner with a back boiler in an old Victorian house, detached, high on a hill in Inverness-shire. I fitted an oil boiler as well, just in case but never needed it.
It was a bit primitive in some respects, certainly as far as he aga was concerned. We had to use a towel rail in the bathroom to regulate the hot water temperature at night but usually only in Summer.
I’m not sure about retro fitting boilers to agas but if it’s on all the time then it seems daft not to use the available heat.

I work in a lot of houses, few are happy with their ASHP. GSHP are not a great deal better.
Despite their efficiency, they still cost a lot to run when the weather gets below 10 degrees. If they are combined with a good solar panel array, then there may be an argument to go for ground source, but I very much doubt you will be able to beat the cost of gas, including the installation of a new boiler.
Add in your lack of insulation, then ground, or air source, shouldnt really be considered.
Get a new gas boiler, when it fails in 10-20 years, G/ASHP may have come of age and be more efficient than now. In fact they are better now than 5 years ago, we’ve had a few changed recently to Mitsubushi units, as they are far more efficient and less failure prone.

An AGA boiler is extremely inefficient and they tend to leak, rusting up the inside of your AGA. Don’t ask me how I know this.

Have you actually bought the house? It sounds like a heap of trouble to me.

(the bedrooms are all in the roof so there’s limited opportunity for roof void insulation,

That’s where you’ll get the most benefit and there are lots of solutions. I’d find a way because the place will never be comfortable until you do. I lived in an old farmhouse, it was miserable upstairs in Winter even with a wood burning Aga going flat out to the point we had to run off hot water to stop it boiling the primary circuit.

40 years on I still have trouble with boiling the primary circuit but now it’s the solar thermal if I go away in Summer without removing insulation from a few pipes.

An AGA boiler is extremely inefficient and they tend to leak, rusting up the inside of your AGA. Don’t ask me how I know this.

Not sure how you can say they’re “inefficient”, how can you actually measure it as the ‘boiler’ is basically a gravity fed wrap-around tank full of water?

Is the AGA on permanently, and do you use it for cooking & heating? If yes, just get a tank added and it’s basically free hot water as it’s almost a by-product.

If the AGA is just a status-symbol, get rid – unless you’re minted and don’t care about the running costs.

We’ve an old mill and have an oil-fired AGA at one end and a wood burner at the other, with just a couple of towel rails upstairs (fed by the AGA). Use approx. 3000l pa and 4-5 cubic metres wood.

But we haven’t mains gas. If we’d mains gas, we’d have gas CH.

The Aga made your farm house misrable more than anything else tbh.

Agas make most folk misrable.

We’ve got air source from NIBE and works very well BUT house is new and extremely well insulated including triple glazed Windows. I don’t think I’d look to air or ground source unless you can get a very high level of insulation with the house being minimum B for EPC.

Reason is radiators and underfloor circuits are typical 30-40C if you don’t want to boost circulation temp using the heating elements. When the system needs to use heating element costs will sky rocket. I think to get a 600 year old up to B would be a challenge.

Mains gas boiler is probably the best answer.

Insulate, draught proof then consider how to heat the property, although be careful with old buildings. Seek expert advice, you can use a wood fibre insulation (Stieco is a brand I have come across the most) that is then lime rendered.

As for heating, the green alternatives probably don’t stack up financially compared to mains gas. Look for cost comparison per kW for different fuels. Mains gas is one of the lowest. Heat pumps aren’t suited to your property unless you can insulate it very well, to better than building regs probably. Biomass has a large capital investment (as does GSHP) that you will be a long time recovering if ever.

If you are SE based there are a couple of people I could point you towards to do proper reports etc.

Mains gas makes a lot of sense of available.
Pellet boilers without the incentive are no cheaper to run than oil.
Batch boilers require more involvement that most can’t be bothered with.

Friend has a batch boiler on his farm as he has the space, he is also a sawmill, so fuel is easily come by, processed and he can self certify the timber to qualify for the grant payments. Boiler heats a 5000l tank that pipes to the old longhouse and new farmhouse (1860s). Neither have ever been so warm, the new farmhouse has had quite a bit of movement in the joinery. The tank is bigger than needed currently, but has extra outlets for potential barn conversions, running the kiln and the ultimate dream of underfloor heated lambing shed.

Is solar electric an option?, another guy near me is using solar panels to power underfloor heating and an immersion tank as the grid is not suitable for selling back to where he is.

Old, poorly-insulated, potentially draughty house with limited potential to make changes to the structure?

Get a new gas boiler, check your radiator sizes, and expect fairly big gas bills? Maybe buy some big jumpers, warm slippers, and get some blankets to reduce your need for central heat?

biomass boilers sound groovy but only if you have easy and cheap access to fuel. In terms of ‘greenness’ they’re only a shorter cycle of carbon burn and capture than burning gas. Unsure how their efficiency and particulate production compares to gas.

Start your reading here – https://energysavingtrust.org.uk/are-home-renewables-right-you/

And have a look at the pence per kw in this table
https://nottenergy.com/resources/energy-cost-comparison/

I’m going through similar, without the mains gas option. Still haven’t worked out a good plan. One thought is solar powered day storage heaters. Don’t know if this is a thing. It seems to make sense to me. Free electricity in the day to make heat for use in the evening. Not sure how well it’ll work mid winter when it is needed most. Also planning to internally insulate some rooms so they can kept warm more easily. I think this can still be done in a breathable way.

Bought a Victorian house a couple of years ago. Previous owner has fitted a Daiken Altherma. It’s a gas combi boiler with a ASHP. So depending on outside temp it will run on ASHP till it gets too cold and then switch to gas. It’s slow to heat up on ASHP, but trick is not too let it get to cold.

ASHP fan is ugly, not as noisy as I thought it would be though. With nothing to compare it too, can’t tell what running costs are like, but it uses ASHP about 80% of time I’d guess. We’d be too cold with just a ASHP though as the old building doesn’t retain heat well.

Agas make most folk misrable.

Ours is left on at the same setting 24/7 and 365 days. We love it and is our only form of cooking & water heating plus the main source of heating.

Whenever I see an AGA on telly and it’s usually got one of those stupid kettles on top and an electric/gas cooker beside it, I know it’s a pure status symbol and they really don’t know how to use it. Hint, the cooking plates aren’t used for 99% of cooking and certainly not for boiling a kettle.

These guys started out insulating old, hard to heat and conservation properties. They have a lot of modern breathable insulation, modern lime plaster and paints.

They offer advice as well.

https://www.natural-building.co.uk/

You will have to jump through hoops to get any form of government assistance with the heating.

An EPC will be required and then you will need a qualified survey to prepare a report detailing why you can’t meet the upgrades to the insulation demanded by the EPC. We’ve just been through all this and in the end just fitted a new boiler (oil).

We had an Aga in the old house and disconnected the hot water tank, as the Aga could never heat the tank quick enough. It works OK if you don’t have baths and just shower.

I’d just replace the gas boiler with a new one.

Obviously more initial work, but savings down the line over gas usage.

OP

fit your multi fuel in the inglenook, burn some logs

Don’t, whatever you do, bother with a backboiler, that right there is a massive money pit that will never pay back. Back boilers and circuits to link them to a central heating loop are a massive hassle to fit and just not worth it. Realistically, for wet loop stuff, gas is first choice, oil second, solid fuel a distant third. I speak as someone with solid fuel central heating – don’t piss about trying to join a log burner to your hot water tank. It is far, far easier, cheaper, simpler, and lower maintenance to have a dry log burner and a separate water boiler of whatever fuel source.

lose the AGA, get a gas boiler, get rads fitted all round

do what insulation you can, without ruining the buildings ability to breathe (which will kill you down the line when damp causes issues)

get some kind of double glazing sorted ASAP, even that naff emergency/temporary stuff will help out through the coming winter

Back boilers and circuits to link them to a central heating loop are a massive hassle to fit and just not worth it.

They are work to fit but as with anything it depends. Also how useful they are depends on how your useage of the fire is and how you get your fuel.

Ours is left on at the same setting 24/7 and 365 days

that would make me miserable thats for sure*. It certainly makes me sad that people still think thats a good thing.

They are less responsive to current conditions than even storage heaters……

*Been here got the t-shirt thankfully it was a rental and i was able to run away fast. Grandparents also had one on the farm – eventually they realised it was wasteful inefficient method of doing anything and it was replaced by a hob and oil boiler – they had to look at the aga till the end though as the kitchen building fabric was built round it.

Have you considered biomass (a wood pellet boiler).

I would (sorry, not sorry) check the local pellet suppliers before going down this route as they are likely to be in short supply after January 1. UK wasn’t making enough for demand last winter and there was a large amount of importation going on. Work ran out a couple of times in the colder months earlier this year as a result and one JIT delivery.

It certainly makes me sad that people still think thats a good thing.

Are we not allowed a warm house, plentiful hot water and all our cooking at a reasonable cost?

Plus it dries out FiveTen’s and anything else put near/on it overnight

Thanks everyone – I think the gas boiler plus looking at insulation where we can makes sense.

Building is in a conservation area but not listed.

We’ve been here since late Feb so not been through a winter really yet, so far we’ve had the heating on for a few hours a day and it warms the house up reasonably well.

We had some Yorkshire sliding sash windows refurbed at the front but fitted 8mm acoustic glass (with lead strip on top to match original) as we’re at the roadside and wanted noise reduction – they’ve made a big difference compared with the old leaded glass panels for both noise and draughts. We’ve refurbed all the other windows and I’m in the process of fitting seals on some – the acoustic glass/lead strip route looks like a goer in the others too over time.

The Aga is purely for cooking and is the only oven/hob we have (bar a microwave) – not had one before but used to it now and we’ll be keeping it when the kitchen is refitted (and not adding a hob or oven). I’m not going to try and justify it as anything more than an indulgence but it works for us and a warm kitchen/overnight drying room has benefits as well as the cooking.

We’ll look at roof insulation but I don’t fancy pulling down all that lathe and plaster – the lathes are about 1cm thick, none of that paper thin Victorian tat 😉 – for access so it may have to wait until the roof needs doing – the bits we can access have 20cm rockwool in them.

The Aga is purely for cooking and is the only oven/hob we have (bar a microwave) – not had one before but used to it now and we’ll be keeping it when the kitchen is refitted (and not adding a hob or oven). I’m not going to try and justify it as anything more than an indulgence but it works for us and a warm kitchen/overnight drying room has benefits as well as the cooking.

+1 and us too.

Have you got use to using the ovens for everything and to plates for almost* nothing?

* – steaks on the hot plate and pancakes on the simmer plate

FYI there is massive R&D/plans to use hydrogen in the mains gas network in the fairly near future. At the moment has boilers have to deal with up to 30% hydrogen so it’ll start that way and eventually go 100% hydrogen. Which won’t just be handy for heating but also filling up hydrogen cars.

Biggest issue with hydrogen is leakage though, that needs sorting before anything else. But yeah, that’s the way to go.

200mm of rock wool is a good start, you would get ~50% better performance from PIR panels though. That would take you to the recommended insulation level (300mm of blanket is equivalent to 200mm of panel, roughly speaking).

You can get vacuum pane double glazing for your application, not sure if that’s what you are talking about. Again, expensive, but your only real option in your case.

As others have said heat pumps are a waste of time in your case. As are a lot of green options tbh, conservation area rules out a lot of things I’d imagine.

PIR panels aren’t great environmentally, look at wood fibre, recycled denim or one of the sheep’s wool insulation.

I have an old wool mill, a massive stone structure with draughts everywhere. I replaced my oil boiler with a wood pellet stove a few years ago. It looks a bit like an aga and is a lovely addition to my kitchen.

https://www.klover.it/en/products/kitchen/pellet/smart120inox

A couple of bags of pellets every day will keep it going all day, keeping the whole place nice and warm. I love cooking on it, and it is a real treat to have a real wood fire in the kitchen.

As a nice bonus, the RHI scheme more than covered the cost of the boiler and installation, so it was essentially free.

The downsides are buying and storing the pellets, then lugging a bag or two of pellets in every day. I don’t mind it at all, but it won’t suit everyone.

I have not been following this sector for a bit but what is the real world experience of the domestic CHP boiler.

Hint, the cooking plates aren’t used for 99% of cooking and certainly not for boiling a kettle.

Sounds very practical then 😉

Sounds very practical then 😉

He is right though. Unless one of you is at home all day and is able to take advantage of a long slow cook. Sunday roasts done on the Aga were bloody ace….but not good enough for me to pay through the nose to run the thing the other 6days of the week.

Lucky oils as cheap as it’s ever been . I was running it during 60 odd p a litre days. Never again

PIR panels aren’t great environmentally, look at wood fibre, recycled denim or one of the sheep’s wool insulation.

They may not be but they perform a lot better than the alternatives. If you have the space to use thicker insulation crack on, otherwise practical considerations have to be made.

I have an old wool mill, a massive stone structure with draughts everywhere. I replaced my oil boiler with a wood pellet stove a few years ago. It looks a bit like an aga and is a lovely addition to my kitchen.

https://www.klover.it/en/products/kitchen/pellet/smart120inox

That looks interesting – we have an old Victorian Industrial building that is heated by a solid fuel stove and a 30+ year old Stella Sprint gas combi both of which need replacing. Will Google them.

Edited to add – how big are the bags of pellets you mentioned?

But that is the argument, is there more damage to the environment from using PIR panels and a bit less fuel or worse insulation bit more heating? And PIR panels are difficult to cut between old wonky joists, leading to air gaps, and actually a poorer insulation job than something that is flexible and suited to the building.