So, I know this is a topic that rightly can provoke discussion, but I thought I'd post this in case anyone has any strong ideas or similar experiences.

My parents have an oldish (1740 or so) farmhouse with infill stone walls. Windows and doors are generally modernish with a well insulated loft. They've done the easy win stuff but insulation to the walls via EWI or IWI I think is a non-starter for them. Their current CH is via radiators and an oil boiler, DHW generally via an immersion for reasons I'm not sure on frankly. The boiler is old, approx 35 kWth and really needs replacement. Having spoken to them, its not well set up, seems to cycle off and on when manually switched on and while it gets the radiators hot, the building does not stay warm for long once they're turned off. They typically run this for 8 hours a day or so, mainly in the winter and shoulder months. I think I'd struggle to get them to reduce their heat demand through further works.

They use approx 2000 litres of heating oil a year which I think is an approx heating demand of 20,000 kW; I have no idea of their DHW usage but I doubt it is huge (2 showers a day).

They had a SAP done when they got the loft insulated for free but I haven't seen it yet.

Replacement options.

No mains gas supply.
Heat pumps are ruled out I think - no desire to replace rads with UFH, flow temps on rads will kill the CoP on a heat pump.
I would prefer not to get a replacement oil boiler as the fuel is expensive.
Biomass - suggested option at the moment but probably pellets rather than manually fed logs (they're in their 60's).

So, I am going to suggest that they investigate a 40-50 kW output biomass boiler linked to a large heat bank / buffer tank (approx 1500 - 2000 litres) that can do batch burns to increase the efficiency and use this to serve the CH system basically via either "always on" at a lower flow temp or at least a longer CH period to try and steady out the heating period. Or would a smaller (and cheaper) burner be better, given it would have to run for longer? Any thoughts? Either way, a large hopper I thiink is necessary as it seems to give a better position when placing orders pellet suppliers.

My other query is mainly around DHW at the moment - should they look to take the DHW via a heat exchanger at the top of this buffer tank (plenty of pressure for mains fed) or fit a seperate smaller tank for year round DHW supply so that in the summer only this is heated? I assume this isn't difficult? I've seen it suggested that the DHW is also fitted with an immersion that could do DHW via PV in future also.

This would reduce the need to disrupt the house significantly and the existing CH and DHW loops could feed straight from the new tanks. Annoyingly, this would likely need a plant room outside, but it could well be cheaper and easier than trying to fit one into the house.

EDIT: I forgot to say that RHI is an option but obviously accreddited equipment and suppliers will push the cost up in the first instance so again, comments on this welcome.

Experiences and recomendations welcome. Thanks - Jamie

Oil is not so bad, a lot better environmentally than biomass, and probably cheaper to install/replace and run.

You could just get the heating system sorted out properly, or at least sketch up the current design and let people on here have a look.

Showers could be done with a relatively cheap electric shower unit. Just make sure you size it right so that is is pleasant to use.

Have a look at the newer generation of CO2 heat pumps. They can reach a higher temperature than the current ones (which are being phased out anyway).

What is important is to get a decent idea of the actual heat loads. Without that you can't size a system properly. This is true for any heating system.

<blockquote><cite>Posted By: Peter_in_Hungary</cite>getting a log burner at the age of 60+ is probably not a good idea.</blockquote>

could not disagree more !
It's like saying, when you get to 67.5 yrs, get rid of the garden...
... or when you get to 72.4 years, get rid of the pushbike...
... when you get to 59.2 years, stop diving...
... and at 64.97 years, you are *far too old* to be on a sailboat...

We are going to live to age 120, for Krike's sake !

I got my wood stove aged 62 ! My only regret is we waited too long, with a smoky open fireplace...
I am now 66 and counting, and the log stove is the best investment we made !
It is five-star, and I intend to change it for a 7-star, and install a heat-recovery air pipe.

I have a lad bring me 1.5 stères once a year, for 90 Euros, and the rest I cut myself - I reckon that we burn one-half for heat, and the other half for fun & social, and I don't need to cycle or run to keep fit !

I take pride in running the stove up to operating temp (150°C) in under 10 minutes so it don't smoke; my record is six minutes !

Everybody around where I live burns wood.

I built two solar wood driers: today was 7°C out, and the log driers were at 21°C.

To dissolve the microparticles, we just... drink

Have a good time, carpe diem : life is short and you're a long time dead...

gg

Posted By: JamsterI forgot to say that RHI is an option but obviously accreddited equipment and suppliers will push the cost up in the first instance so again, comments on this welcome.

Yep, and the requirement to purchase the pellets from certain suppliers will also call into question your characterisation of biomass being cheaper than oil as a fuel. Who knows what will happen in the future?

The only real answer without a crystal ball is demand reduction.

Posted By: gyrogearcould not disagree more !
It's like saying, when you get to 67.5 yrs, get rid of the garden...
... or when you get to 72.4 years, get rid of the pushbike...
... when you get to 59.2 years, stop diving...
... and at 64.97 years, you are *far too old* to be on a sailboat...

At 70 this year I do all of the above (substitute the occasional dive for the sailboat) and I also run a farm. We have had a log burner for the CH for the last 23 years.
My point is that adding a log burner for CH builds in a 'must do' into your life at a time when things an be unpredictable. Two of my friends (similar age to me one in the UK one here) had what they thought was a pulled muscle only to find that they needed a coronary bypass. The list above is all optional, you an reduce the size of the garden or cycle less, take the bus more etc.. If you install log burning CH you are stuck with the 'must do' for a long time or be faced with an expensive change down the road. A neighbour of ours heated with wood and the social worker had to bring in the wood every other day because the were no longer capable but in other respects they were (more or less) independent. I would much rather have things I could manage down over the next 20 years rather than build in something now that was a 'must do' and if I could not 'do' then it would threaten my ability to live where I am.

Posted By: Peter_in_HungaryIf you install log burning CH you are stuck with the 'must do' for a long time or be faced with an expensive change down the road.

Hiya, PiH !

Of course I agree entirely !
(I was actually surprised to find myself saying I disagreed, LOL).

However, in my case, the wood burner does have a back-up already - namely, the electric radiant floor that we no longer use...

All it takes is a visit by the leccy board, to UP the main C/B from the 9 kVA I ordered, back up to the 12 kVA it had been at for 30 yrs...

All I then have to do is calculate the respective disadvantages from breathing particles, to walking around (and sleeping) in an EMF haze...

gg

Posted By: djhThe most noticeable effect is a magnetic field and I've only ever seen that affect anything once. I used to work in a basement office, and the mains inlet for the six-storey building passed underneath that office. CRT computer screens had a noticeable wobble on them in that room. So they had to move us out :)

Are you sure that it was the screens that had the wobble and not your eyes

Posted By: Jeff B The boiler manufacturer claims it to be low maintenance (self cleaning etc.) but that is simply not the case. I have to give it a thorough strip-down clean very month which almost equates to the annual service in terms of work to be honest. I know my wife could not do that. It is a filthy job carried out on my hands and knees. You don’t say how old your parents are but I suggest they would need to consider that aspect.

We have a buffer tank that supplies the C/H system and a separate, sealed, indirect, DHW tank with a solar coil. If I was doing this today I would not phaff about with a glycol solar thermal system but get an Immersun type gizmo, then use my PV panels to run the immersion heater.

Thanks Jeff - I was definately wanting something 'light-touch' so that's another vote against biomass to be honest. I think whatever they go for should have a PV input for an immersion in the summer when the the main heat supply might not be needed. The other thing to mention here is that they have an electric AGA... I know, I know.... In their defence, its a 40-year old one that was converted from solid fuel to oil and from oil to electric, and probably their main luxury!

Posted By: JamsterThe other thing to mention here is that they have an electric AGA... I know, I know.... In their defence, its a 40-year old one that was converted from solid fuel to oil and from oil to electric, and probably their main luxury!

Agas are a bit like wood burners - they are a lifestyle issue / choice

<blockquote><cite>Posted By: owlman</cite>I don't think you've mentioned Air/Air heat pumps; from your initial description I assume you meant Air/Water.
I have biomass but I opted for a slightly different control system inasmuch as the CH pump stays on 24/7 for the 5 or 6 months of the heating season. The house temp is controlled, not by the pump and or some boiler switching on and off, but by the temp of the circulation water. Sometimes this is barely warm other times hot.
By keeping the house constantly heated all winter in this manner I think has resulted in a home that is always warm.
In your case an Air/Air system running 24/7 may provide that basic background warmth with something else conventional providing boost, perhaps in selective areas, should it be needed.</blockquote>

Can I ask please, what is your heating demand and how many tons of pellets you use p.a.? I went through a similar exercise some time back of keeping the boiler on overnight on the theory that by keeping the house temperature "ticking over" overnight (rather than allowing the building fabric to cool overnight) this would reduce the overall pellet consumption. It certainly did not in my case!

Hi Jeff B,
Apologies I didn't specify, I burn log-wood not pellets. I was using the 24/7 heating bit to illustrate the option of having a constant background heat (e.g. heat pump), which his elderly parents could supplement, as required, with other means.

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Posted By: SteamyTeaThere was some concerns about the price a few years back when the RHI was introduced.

At £238/tonne, I think that is around 5p/kWh (using 4.8 kWh/kg).
E7 is about 8p/kWh

So not much difference is running costs after efficiency is taken account of and you don't have the storage issues or the maintenance to worry about.

Yes there was. However from Dec 2011 to May 2014 the cost was pretty static, then suddenly a 10% jump and pretty static since then.

Heating oil is currently about 50 p per litre here, so about 5 p per kWh (using 10 kWh/litre). Pellets are 24p per kg, so about 5.3p per kWh. Oil prices are creeping up again so there is almost parity between them, which I'm happy with. For quite a while oil has been much cheaper in terms of pence/kWh than wood pellets - I'm amazed that there is any market for wood pellet boilers!

Thanks again all of you for your comments - this has stalled for now as they're faffing about quite frankly - but what you've all said has certainly given me food for thought. Perhaps I can get them to at least overhaul the CH system this summer and see what state its in, and hopefully not disturb the any sludge so much that it kills the boiler...

If they do come back to this soon, I'll update this thread with my decision-making!

VictorianEco, I don't think the house is well insulated (stone solid walls) enough to run the lower temps ASHPs have high efficiencies at - they just need to pump more heat into the property sadly I think!