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Absolutely not. It's great having discussions and picking up ideas, knowledge and experiences of others. If you don't mind, I'd like to know how much you pay for pellets and which boiler you have installed. PM if you like. Thanks

I agree. No one should base their "payback" or whether they can afford a biomass heating system on grants that may or may not happen. Biomass is not for everyone. If you are replacing a gas boiler, fit a new condensing gas boiler. If you live off the gas grid in a rural area then biomass is certainly worth considering.

Hi Kevinjohnsonmbe Thanks for some good points you've raised. VAT certainly is 5% on installation of biomass and renewable systems. This will include any building work related to the install. Absolutely people should be aware of this as there is a big difference between 5 and 20 % of thousands of pounds. I've just seen your correction of RHPP to RHI and yes the government initially were going to launch April 2011 but have been dragging their feet. Until it actually happens, there can be no certainties. The latest is that it will run for 7 years rather than the 20 which was an earlier indication, and introducing a teired approach is very unlikely, houses will need to reach a certain level under a green deal assessment but to be honest it isn't too difficult. £3k is the annual payment based on 25000kwh produced and 12.2p per kwh being paid. It's not really a bold claim, just maths based on the information given. Some manufacturers will say they can work without an accumulator if the boiler is sized accurately and there is no store of heat, I would imagine you would need a heat leak radiator which would at least match the output of the boiler when in slumber. You are right, I think this is wrong as the boiler will be in slumber mode too often and efficiency will dramatically reduce. By far the best method is as big an accumulator you can afford and accomodate which makes the use of the boiler more flexible and efficient. Thanks

RHI - You get paid a fee for every kilowatt hour of heat the boiler produces heating your home. The amount of heat produced will either be measured by heat meters fitted to the pipework or it will be calculated based on your house size, boiler size, heat loss etc. which will give an expected heat consumption. Currently biomass boilers are set to receive 12.2p pet kwh produced. As a guide, an average house will need about 25, 000 kwh annually for heating and hot water. This would give you just over £3k per year for 7 years.

Hi Gary. Very dependant on which boiler you go for and which manufacturers advice you "beleive". Kit can range from £6k to £20k and some mf's will advise against fitting an accumulator tank. I fit HDG boilers from Euroheat. They are the best boilers on the market, their support and tech backup is excellent and they will last 20yrs plus. I can't comment on others but I always say do it once and do it right. You're looking at an install starting at around £10k plus vat for their base model log boiler. Like I said earlier there are many variables and every install is different. Plus the soon to be released RHI grants make the install cost easier with an annual payment of around £3k -£7k for 7 years depending on the boiler size. Thanks

It certainly can. By using a thermal store or accumulator tank you can link together many heating appliances. I install biomass, heat pumps, solar and gas heating systems. Am currently planning a biomass log boiler install at home and keeping my oil boiler as a back up.

Mikeyne Great to hear the positive experience you are having with your boiler. 3kw soujds about right for the useful heat per kg of wood and good to hear no oil being used. When sizing an accumulator, the calculation is fuel chamber volume in litres x 13. This will give minimum size required. The larger the accumulator however, the more flexibility you have with the use of the boiler. This is because the loading valves fitted to the system mean that the accumulator is heated from the top down, so the more cold water you have below the useful hot water, the more scope there is to store the heat generated from a full burn at full rate. It will prevent the boiler modulating down and losing efficiency and potentially extend or decrease the time between burns. It sounds like your system is perfectly suited to your house and your use of the system as you are probably using some of the heat that is being pruduced during a burn as wel, as the accumulator being loaded. Kw rating of log boilers is almost irrelegant to some extent, the key to sizing a system is the fuel chamber volume. Depending o what boiler you have, you mag find the fuel chamber is 250 litres which match your 3000 ltr tank. Some manufacturers will say you don't need an accumulator at all to run it. Well, it will work but efficiency will suffer massively. It will be interesting to compare wood usage to oil usage over a year. Really pleased to hear such positive log boiler stories.

You're absolutely right, chip would've been more suited.

There's your answer John. Running 2 x 45 kw log boiler will only cope with about 600m2 of floor area, about 2 large detached houses. Unless they are running 24/7 then they may cope with 6 if well insulated. You are dead right, a chip would've been a much better bet. Also a lot more convenient and automated. Cheers

Good point Gensetsteve. Using what you actually have is very important. Even if the grants didn't exist I would still be going the log boiler route. Initially I will keep our 1 year old oild boiler as a backup. You're right in ten years wood will be expensive and oil more expensive. We have 6 acres which I'm planning on growing src willow to provide logs for the boiler in the long term. 1 acre will give 6-10 ton of dry wood per year. We have no log burners inthe house and we're carrying out some renovation work so im looking forward to getting the boiler to see how it goes and as a showpiece for prospective clients. I'm not a fan of installing stuff because it is in fashion, I would much rather give good advice and install what is needed along with energy efficint advice to make the best of what people already have. Cheerz

Hi Jon Sounds to me like they are burning wood above 20% moisture content. The more moisture in the wood the less heat comes out. That is the golden rule, get moisture to 20% or below. If the moisture is at the correct level then 100 tonnes will give 400, 000 kwh of heat which is the equivalent of 40, 000 litres of heating oil. This woild heat around 10 large detached family houses. Unless their house is huge it sounds like heat is being lost somewhere either through under ground pipe work or burning the water from un seasoned wood. I know of a similar situation where they were burning about 10 times the expected volume of chip and it turned out to be deteriorated under ground insulation of the heat main and they effectively had underfloor heating in the field!

Thanks Jon Good advice, there is no doubt that running a log boiler takes commitment and hard work especially having to fill at least once a day in winter. Chip is certainly more convenient from a user input point of view. However, with a correctly sized accumulator which is key and a thermally efficient house, log boilers can be very cheap to run..............commitment still required!

Good stuff Big Chris. General rule of thumb is volume of house multiplied by 40 gives heat loss in watts for an okish insulated house. Most of our house is 1920s built with the new bits being well insulated so overall okish. Log boilers are sized according to fuel chamber size and you'll find a 30kw boiler will have the same chamber size and indeed the same price tag as a 50kw boiler, just with different programming of the software. In some, not all cases. Also we'll have some underground pipe work which will have a small heat loss. Good to hear the Vigas is going well. Do you have an accumulator tank? Also how often do you find you fill it during the winter and where are you? Great to hear love for the biomass.

Sandspider - not ideal to light a woodburner in the summer. Biomass log boilers though are 90%+ efficient and stay luke warm on the outside. Better than oil boiler.

True that Timbercutterdartmoor. I'm installing a log boiler, not a chip boiler. A mix of hard and softwood is good.