It was worth a go – wood pellet range cooker test

Wood pellet and Log range cooker

The National Trust has hundreds of oil range cooker / central heating systems (Aga, Rayburn, Stanley) across its 20 or so thousand buildings. We are looking for a more environmentally friendly but economic equivalent cookers. As we saw before Christmas there is such volatility in the price of oil and the CO2 emissions, conflicts,  environmental damage that oil causes  should be raising alarms with us all. The NT have an aim of ‘getting off oil’ But its not simple since we are all including organisations in our way addicted to the stuff, its what our entire economy is built around – enough with the preaching…

Tŷ Mawr Wybrnant

Tŷ Mawr Wybrnant

Ty Mawr Wybrnant deep in a valley near Betws y Coed in Snowdonia is an important icon in Welsh culture being the Birth place of the Bishop William Morgan. He was the translator of the Bible to Welsh recognized as one of the key aspects in saving the Welsh Lanuage. Next to the house is the house of the custodian which had until recently a very ancient oil heating system together with and even more ancient oil tank . npower agreed to fund a trial of a wood pellet and log range cooker to heat water and central heating and this would be an excellent pilot for the whole organisation.

Scandinavian / Austrian/German houses retain their heat much better than granite Welsh cottages do and so we suddenly found that the few wood pellet range cookers we could find were large in size but small in heat out put . so we called on the expertise of an engineer to look at the problem in a bit of detail and no mater what we did we could not get the house ‘heat load’ lower than around 19kw and the best range we found (and bought) was 7kw which was ideal for the Austrian farm house it was designed for. We contacted the company and asked if they could increase the output to 20kw which they would if we placed an order for 500. So we compromised with the pilot (not the order of 500!) – we added a Clearview 650 wood stove with a back boiler and 5kw of Worcester solar thermal, insulated the house with wool and hoped for the best – on paper the sums added up!

Ah – 7kw of Austrian heat output on logs was based on high quality sub10% moisture Austrian timber, the availability of logs with tis moisture content is not thick on the ground in the uk and a bit expensive to buy. With pellet the system was a form of batch boil  which was not ideal.  (on then off) The custodian and his wife having struggled through 6 months of pilot had to call it a day and the stove was replaced with an Esse Ironheart which will burn just about anything but not as automated and would not be such a like for like replacement.

I feel a British wood pellet range cooker is not far away and it was worth trailing the best available at the time. But the main lesson was that we should not have used such a low output range to provide the base load of heat without either having a decent back up or insulating the house a lot more – but technology and understanding is moving very quickly in this field.

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National Trust Green Energy in partnership with npower

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42 Responses to It was worth a go – wood pellet range cooker test

  1. The above is rather idealistic in tone, and entirely without substance: what make and model of wood pellet range cooker was it????????????
    {The whole point in me finding and reading this…………….. }

    • Keith Jones says:

      i agree it was idealistic. but we also went the whole hog in terms of heat loss work, M&E design, additional load from a new fire and a solar thermal system as well as overhauling the hydraulics. we knew that 7kw was pushing it but because it was the only thing on the market in terms of a replacement we needed to find out what we could do. we learnt a lot and know what we should now be looking for both from an engineering side but also what a user wants and should expect. idealistic – we should all be. naive i hope not based on all of the design and understanding which went in initially. More than happy to let you have the full specs we developed. substance – your opinion but thanks for the reply
      Make LOHBERGER LCP 70

  2. Scott says:

    I too am interested in a pellet/wood burning cooker as I want to get away from reliance on oil fired heating but require some form of automation as we are out at work for long hours and can’t take the risk of the fire going out and the house going cold. I have looked at the Lohberger range and the spec looks ok (when combined with our huge Franco-Belge Limousin stove) but they have a very industrial look to them. I hope that somebody will come out with the sort of model we’re looking for as I would be surprised if they didn’t already exist in Scandanavia or Italy (where wood pellet systems are more established). Thanks for your report although more deatil would have been appreciated.

  3. Duncan Dobson says:

    I am also looking at this, did you consider the Eco range cooker company they do a pellet fired aga type cooker. It may be that is very new. It certainly looks more attractive and appears to very controllable. I’d be very interested to know if you have looked at them since this project?they also are uk made and based.

    • Keith Jones says:

      No we haven’t. these were not available when we did the pilot a few years ago. part of the issue we had was the energy output was very low and we knew we needed at least a 15kw system, plus an automated feed system, good modulation. have just had a look at the manual for the AGA. 14kw cooker with a 4kw space heater. nice cooker and small space heater but does not do hot water and central heating and so not a like for like replacement which is what we are looking for. but I’m sure there are circumstances where it could be used but not for the bulk of replacements we are looking at. all the best and thanks again

  4. Glyn says:

    Helo ‘na; rwyf i hefyd wedi bod yn edrych am sustem i yrru’r gwres canolog ac efallai i goginio a chadw’r ystafell yn gynnes. Wedi sylwi bod cwmni o’r enw Klover yn gwneud Smart 80 a’r Smart 120, eitha ‘ diddorol! Hwyl, Glyn.

    • Keith Jones says:

      edrych yn ddel iawn. beth ydi ei boiler output? yn enwedig os oes system gwres canolog. Oes MCS er mwyn cael taliadau RHi? beth am darnau – pwy sydd yn cadw ee igniter. hwyl am y tro

  5. Pingback: Hafod y Llan farm house – looks like we have a heating strategy | National Trust Going Green

  6. Stephanie Wolfe Murray says:

    How about the Klover Pellet Utility Stove PB24 from stovesonline with a heat output of 24kw?

      • Stephanie Wolfe Murray says:

        Hi. I’m interested that you’ve ordered one of these Klovers. Is this for you personally or another experiment? Does it answer your doubts about the previous stove you got for the Welsh couple? We are very interested in getting one ourselves although it’s a shame that the oven is smaller than average. There are other questions I have such as how much does it heat the room it’s in when just ticking over at bare minimum, how responsive are the cooking areas (both hot plates and oven) etc.
        As one of you said in a previous article, if Klover gets MCS accreditation then it has to be a no-brainer. What is it that makes it so much more competitive than its more established rivals?

      • Keith Jones says:

        this is another of those experiments and not my house. the turn down is not that low 5kw but they are developing a canopy cover for it. if your room is big enough then 5hw will be ok. (you can always switch it off when its warm enough! took 30mins to get the oven up to 250c when i was there which i am happy with. Its the only stove i have seen where you would you might receive an annual payment for generating renewable heat.(it will pay for itself) once its in for a while your more than welcome to come and have a look and chat. we will also be honestly blog-ing on its performance and livability aspects

  7. Geoff Procter says:

    I have followed your work on the day Klover 120. I want to replacea a much loved Standley range cooker (Which also provides hot water and heating) witha wood pellet range cooker.

    So far your experiments with the Klover Have encouraged me to make the next step and approach an. installer.
    But what about its livability?
    I would welcome your final thoughts on the Klove’s performance.
    Regards, Geoff

    • Keith Jones says:

      livability is the key test! cooker arrives on Tue. finalising the detail esp the haudraulics. we have a second LPG boiler in the house and need to combine both heating systems. either buffer (hot water tank) or a H2 panel. finalising now. will let you know how we get on via the blog!

    • Hi we are the dealers in mid and south wales and Herefordshire; the klover 120 is MCS accredited so eligible for the RHI when it comes in, and the £950 grant. it is about 28KW output, is 120cm wide and needs a service gap each side of 500mm. If you need any info or want to see one we will be at the Smallholder Show at Builth on 18th and 19th May with our showroom model, best regards Gaynor

  8. mikestasse says:

    I’ve converted an AGA to wood in Australia.

    I can put enough dry hardwood in it at 10pm before going to bed, and it’s normally still hot enough to easily restart at 6am. Don’t know how you’d go about importing a kit from Australia, but AGAs are going cheap now no one wants to run them on fossil fuels anymore…

    • Keith Jones says:

      thanks for this. the conversion kits are here as well. the issues we have are multiple. small load capacity in the Aga, high hot water demand, high heat loss in the types of building we have, (the range cookers are used as central heating systems) wood fuel which wont go below 25% because of atmospheric humidity in the climate we have = does not really work over here. fine for space heating and some hot water but no good for the biggest energy demand which is whole building heating. you can still pick up solid fuel 1930’s to 60’s Aga’s over here (no back boiler) all the best

  9. mikestasse says:

    Hi….. AGA made solid fuel burners until 1972, and at least some of them must’ve had boilers because mine has (made ~1952).

    It’s interesting that wood conversion kits are available in the UK, because I get hits on my blog from people wanting to do this from all over the world, and I was starting to think I was the only source of info on the whole internet!

    I’m not knowledgeable with all ranges available obviously, but one aspect of AGAs that I think makes them superior is that they are thoroughly insulated and may heat water better than other types of ranges because they put more heat into the boiler rather than into the kitchen – such heat only heating the kitchen…..

    Re your “high hot water demand”, what’s causing this? IF (as I suspect) it’s caused by showers, there are ways of ameliorating this with low flow shower heads. And I trust you don’t wash your clothes in hot water….

    Energy efficiency is ALWAYS the best and cheapest form of energy generation. I have proven this beyond all doubts in our house (admittedly in a warm/hot climate)

    • Keith Jones says:

      agree with everything you say…but. we have a heating demand of around 16MW on average in the UK per house hold and hot water demand of around 80 to 100litrs per person per day. comes from having a wet climate! i think its mid spring here but the log stove still on as its around 5c tonight. the calorific value of fire wood is also lower because of the higher water content due in part to the higher atmospheric humidity. (western temperate) average rainfall where i am is 2.7m per annum can be as high as <4m pa in places. 100% atmospheric humidity v common and uncommon falling below 70%. all in all the agas and wood have been problematic. then we get to the fuel availability and distribution in the UK. we must face the fact that we are a small overcrowded urban little island and i think i read that if we convereted sustainably everything we could to biomass heat then this would give us around 7% ish of the UK need (efficiency and all that plays a part)
      in an ideal world we would lower the heating demand, hot water demand, fuel management and then we might get there. friends have quite a few Esse's which they are very happy with as well as Franco Belge

      on the conversion kits. Google threw up quite a few over here eg

      agree with the countries. have had 127 countries in the last 12 months

  10. Glyn Tomos says:

    Helo ‘na ‘to. Erbyn hyn wedi cael stof belets wedi ei roi mewn ar gost o £6.5k (yn cynnwys grant RHI). Mae’n rhoi gwres o 26kw pan mae’i angen, ac yn hwylus iawn. Nid y’wn gweithio i goginio ond yn cynhesu’r dwr a’r rads yn hawdd. Costau rhedeg ar hyn o bryd yn debyg i LPG ond y ty yn llawer mwy clyd a chynnes. Wedi cael pelets yn lleol a reit rhad. Un anfantais manteisiol: rhoi’r pelets mewn yn feunyddiol ond gweld maint o danwydd sy’n cael ei ddefnyddio.

    Yn dal i edrych ar y Klover a meddwl falle bo’ ni wedi gwrthod stof i goginio arni er base angen talu £2.5k yn ychwanegol! Gweld bod AGA yn gwneud stof belet erbyn hyn.

    Wi haf dda tecnoloji!! wedi cyrraedd AGA erbyn hyn!
    Cofion, Glyn

  11. Ben Griffin says:


    I see you used a Klover 120. I am interested in installing one of these as they are now MCS registered and will be availble for the RHI. However please can you let me know how many kg’s of pellets you burn per day or approx how many tonnes a year. My rough calcs suggest that you could fill the hopper (32Kg)every other day to keep it burning and that would work out around 6 tonne a year = approx £1200 / yr. If I installed an Esse log fired range and used 6 tonnes of logs I could get them for £50/tonne (hardwood) that would only be £300 / yr (but not grant to install and no RHI.

    Please can you give me an indication how how many pellets you are using?

    Many Thanks

    • Keith Jones says:

      thanks for this. the house is curetly going though a whole bag every 2 to three days. We have not run it in winter and so dont know how much it will go through at full tilt. But it is a bit of a ‘how long is a piece of string’ because it depends on how much heat and hot wate you need. Pellet is about 4000kw per tonne and logs at sub 305 moisture is about 3000kwh per tonne. Copmaring an esse iron heart to a pellet system is more than cost. labour is more on a log system (which is ok as long as you factor that in) pellet is also fully automated and so frost protection and early morning startup is sorted. RHi helps a lot but they are two different systems and its more than the cost of fuel. will blog once we have a long cold spell. all the best. Keith

      • Ian Bowles says:

        Hi Keith.
        I am Looking at the Clover 120. Am I correct in thinking that the RHi covers the fuel running costs?
        How noisy is the Clover and does the noise come from a fan or the pellet feeder?
        Do you see the clover as a Cooker that heats or a Central heating boiler that cooks.
        What happened when you fitted the cover plates? I assume that they keep the hot plates hotter and reduce the heat output to the kitchen. Did the water heating become more efficient?
        Sorry about the raft of questions but there appears to be a bit of a black hole in reviews of the Clover Smart 120.
        Thanks Ian Bowles.

      • Keith Jones says:

        the RHi is designed to recoup your capital outlay. the noise is fine i.e. its not an industrial one. if you have a fan oven then that will be noisier. central heating which cooks. we are thinking of installing a simple narrow induction hob for the summer but have not needed one yet. have not received the cover plate. that reminds me i must chase it up. the system is more controllable than the old rayburn and so to answer your question yes it is more efficient but i think that has something to do with the new secondary glazing

    • Hi Ben see my reply to Andy below, if you wanted some stats and feedback we can get you some clients to talk to we’ve been fitting them since they were mcs accredited regards Gaynor

  12. andy harrap says:

    i too am thinking of getting a klover 120 but cannot find much info about them apart from the importers. I am intending to replace a solid fuel Rayburn. I think I am happy about the heating ability of the stove but have doubts about the cooking part. Do you have any comments about this aspect. I see that it heats to 250 in about a half hour (is this from cold?) but how controlable is it my wife struggles with the need to open up the Rayburn a long time before it is actually needed also the Rayburn takes a long time to cool down so things you want to simmer just boil to death. I would be interested to have your thoughts, if it is as good as it seems then it seems a good buy.
    Many thanks

    • Keith Jones says:

      Hi Andy
      the controllability looks ok but not been used in anger. I am going to be doing a full xmas dinner on it in a few weeks (photo op’) and will let you know. We have been looking forward to receiving the new retrofit insulated hot plate cover which should also push more heat into the stove. overall its been fine but still waiting for the cold weeks so that we can see if it can do both the cooking and and heating. Saw one go up to 250c in 40 mins but there again no big heating load on it. To date we are quite happy with it. Keep watching the blog!

    • Hi Andy we have fitted several of these now and we have clients you can talk to who have been using them for cooking. We have recently fitted one in a pub kitchen. .. do give us a ring, ask for Ian, no pressure or obligation

      • Andy Harrap says:

        Hi Gayor, thanks for you reply. Yes I would be interested in speaking to some users, it has been so difficult to find any reliable information and feedback. I guess you must be one of the NT team
        but I cannot find you in there I also cannot see a number to ring.

  13. Joe Fergusson says:

    Hi Keith – I’m just joining the party excited to hear more about living with the Klover Smart 120. I’m hoping that you have had enough cold nights in the past week or so (it was 5 degrees here in Ayrshire last night) to be able to give us an insight into the likely performance of the range when asked to heat the house as well as cook. We can’t wait ’til Christmas! Also, can you tell us the minimum practical clearance required at the two ends of the unit? Do both ends need the same amount?
    Many thanks

    • Keith Jones says:

      Hi Joe. Still not cold down here. Its a balmy 9C here. But the stove is behaving well. we are also looking forward to receiving the retrofit hotplate cover. the stove has a 5kw heat emitance at tick-over and so the plate cover should help. You need access to both sides for servicing and charging up/ draining. we have a good 30cm either side. we have planned to put removable shelves either side (stainless steel)

      • Joe Fergusson says:

        Thanks, Keith, for the swift response. Much appreciated. 5kW is a LOT. When you say ‘at tick-over’ do you mean whenever you are using the oven, or whenever the central heating is on, or either? Is that cover a cost option that, with hindsight, you would have ticked off when ordering? What’s the added cost? I wonder where that minimum 5kW goes when the cover keeps it in. Is it all diverted to the buffer tank? Can you cook without heating water at the same time? Is the noise of it firing ever intrusive? SO many questions – suppose what I need is the manual, except my Italian is non-existent…

  14. Lucy Telling says:

    Hi Keith,

    Just wondering if you had any updates to the queries and discussions above re the Klover performance, please, now that we are half way through winter?

    We are strongly considering swapping from a wet electric CH system to biomass in the near future, so would appreciate any further comments that you have, as the Klover on paper seems to tick a lot of boxes. Also, does anyone know of a Klover within about 100 miles of Glasgow…they seem to be impossible to see in the flesh!

    Kind regards,


  15. Margaret Hughes says:

    Hi Keith
    So, how was Christmas dinner cooked in the Klover? Has it continued to operate and heat your house adequately and have you ever had any maintenance or reliability issues?
    I’ve been looking at the Lohberger LCP75 as Tasha from YouGen has found out that they are in the middle of developing a model with an automatic pellet feed from an external hopper. Apart from the fact it only produces 7Kw, which might not be sufficient for most British homes, did the tenants who used it have any reliability or maintenance problems?

  16. John says:

    Hi I have heard that Klover have just developed a Klover Smart120L which is totally on wood not
    Pellets, but I have also been told by Klover themselves that they are now going to develop a Klover 120 Smart that uses both wood and pellets just like their bi fire range. I feel that I would love one of these so that it will give me two options instead of relying just on one source and if the heating is really high this will be great. What are your thoughts on this. is it worth waiting till they
    have brought it out? I just hope that it will throw out more heat than the Lohberger.
    John Caley Isle of Man

    • Keith Jones says:

      sounds encouraging. the only caveat from my side would be what sort of output would they expect for 25% moisture. the 15 / 7 from pellet is based on 10% moisture level. In the Uk you would need kiln dried logs for this level of moisture

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