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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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    • CommentAuthoredwinvanek
    • CommentTimeSep 14th 2007
    Over the last 6 months we have been considering the replacement our old oil fired central heating boiler with a log boiler as both our tank and boiler need to be replaced over the next few years. We have compared alsmost every manyfacturer available (Dragon, Atmos, Vigas, Froeling, Hoval, Baxi, Mescoli, Viesman, ETA, Herz, Biotherm, Treco, etc) and haven''t been able to make a decicion yet. Recently we started thinking about keeping the oil fired central heating and adding two wood stoves, one connected to the warm water tank.
    My preferde boiler would be the Austrian ETA boiler which I have seen in operationa t various locations in Germany, but the boiler itself without heat store and other component, flue and installation is close to 6K, which is too much. The middle way would be a Baxi Solo Inova. Does anybody have any experience with Vigas and Atmos boilers, which are the most economically priced boilers. The pros are: renewable ennergy, affordable fuel the cons are: costly, not as instantly controlable as oil and gas, bulky and expensive to install.

    Before finally making my mind up I was wondering weather anybody who has already installe a log gasification boiler would be willing to share their experiences and or frustrations?

    • CommentAuthorJohan
    • CommentTimeSep 14th 2007
    Don't know which one to reply to, so many posts... :wink:

    The Baxi boiler is top quality. If you buy one with lambda control you'll get over 90% efficiency as well! :smile:

    The ETA boiler seem to have very similar specifications/performance, the other ones I don't know.

    I don't know how big your house is though, but of you're going for a log boiler you also need a large accumulator tanks if you want it to burn efficiently. Probably 1-2m3, but that depends on the heat load.
    • CommentAuthoredwinvanek
    • CommentTimeSep 14th 2007
    Sorry about the duplicate postings something went wrong. Thanks for your comments. I have three bedrooms but a lot of living space, two bathrooms and about 13 radiators in total. I will probably need a 25KW boiler with a 1500 litre heat store. I might fit one tightly into the house or will have to loose my workshop.
    A subject close to my heart.

    I have the Atmos 20kw 1200ltr tank 7 rads and this is just enough. I would say the Atmos is fine and spend more on your accumulator(mine is simply an insulated steel tank).

    Make sure you have plenty of space to store wood as that has been my downfall.
    • CommentAuthorJohan
    • CommentTimeSep 17th 2007
    Remember you can store roughly 30kWh (with a Delta_T of 50C) in 500l of water. So if you go for 1500l and 25kW boiler you'll need to fire the boiler for 3.6h (assuming no heat draw from the store) to fully charge the accumulator tank. Sounds like you could maybe do with a 35kW boiler to shorten the laoding time a bit. Have you got any idea of your heat load?

    The bigger store you have the less often you need to light the boiler. It's just convinient if you don't need to fire it up for more then 2-3h every day.

    Also if possible it's a good idea to put the accumulator tank in the house, that way at least any heat it looses will heat the house! :smile:
    • CommentAuthoredwinvanek
    • CommentTimeSep 17th 2007
    Good to hear fromsomebody with an Atmos.
    I haven't done a heat load calculation yet but will do this shortly. So far I have assumed requirements for a boiler based on our current oil boiler which is 20kw. The main problem with our house is that it is an ongoing project for the next 5 years.
    We have an old part to our house over two flours with very thick walls that seem to retain a lot of heat, which will be even better once I installed the caps on the two unused chimneys and added a other layer of insulation in the loft. All the window here are single glazed bay windows at the moment, two of them now have internal wooden shutters for blackout and insulation.
    The back part of our house is a single story 1980s extension (study, hall, livingroom, kitchen and bathroom) that is already insulated and has double galzing as well as an open fire place that at some point will be replaced with a stove. I am also planning to install a DIY solar hot water system in the near future, I did the LILI course earlier this year.

    Any views on using two smaller heat stores instead of one big heat store and the use of a seprate hot water tank for connecting up to solar or using the heatstores for this purpose?
    • CommentAuthorJohan
    • CommentTimeSep 17th 2007 edited
    If you require a 20kW boiler now, your wood boiler will need to be a lot bigger then 25kW if you don't want to be feeding it continously!

    I think you need to look at your heating requirements before you steam ahead. A wood boiler set up is not trivial, and can get pretty expensive with all the bits you require. Insulate and draught proof first before you go and get all the bits, that'll be a lot cheaper to do! :smile:

    Two stores are fine, you get slightly higher heat loss though as the over all surface area goes up.

    Seperate solar for DHW is fine or you can combine it with the wood boiler. Personally I like the combined system as the solar panels work more efficiently. On the other hand you do require a lot more m2 of panel. Just a matter of taste I guess...

    For combi systems have a look at this article:

    • CommentAuthoredwinvanek
    • CommentTimeSep 18th 2007
    Thanks for this information Johan, I will have a read throught it this weekend, also found some of your comments in an ealier discussion. Comming back to our current boiler, we only tend to use our oil fired boiler for a few hours in the morning and a few hours in the evening.
    I am very much aware that the installation is not trivial as I costed out the various systems and talke to installers. Although I would prefer to insulate my house first I will probaly have to do this in parallel to installing a boiler and heat store as I am not sure how long my oil boiler and oil tank will last.
    • CommentAuthorJohan
    • CommentTimeSep 18th 2007

    I forgot! You can also have a look at the Navitron forums there has been a lot of discussions about similar setups there, you might find them useful! :bigsmile:
    • CommentAuthoredwinvanek
    • CommentTimeSep 20th 2007
    The biggest problem for me seems to be where to place my boiler and heat store. The easiest would be to place them in the garage but this would mean that it would be difficult to link up to solar as this roof is east west while the roof on the main house is south facing in addition there would be a connection of about 6 meters of underground pipe required for connection to the house. I seem to be able to get the heat store or the boiler in the house but not both, unless I would install the boiler in the study (which used to be the kitchen) in connect it to the old chimney in the main house or would be able to place the boiler in my conservatory which is 5 * 6 meters connected to the thermal store in a separate room about 4 meters away. Apart form the fact that I would need to get planning permission for the flue, would building regulations allow this? The problem I see with the boiler in the study would be the air movement.
    • CommentAuthorEcoman
    • CommentTimeSep 21st 2007
    Hi Just have a look at the swedish Effecta boiler working with a eurofire 20 kW pellets burner head. I think you will find that this package will do a good job for you and not cost as much as you are being quoted. Advantage with pellets is the obvious CO2 neutral, much cheaper than oil and minimum servicing. You will need a hopper or silo to go with this, but pellets require much less space than logs, and a lot less humping. (pellets need just under double the space, for the same amount of energy as oil)
    • CommentAuthoredwinvanek
    • CommentTimeSep 21st 2007
    The reason that I haven't been looking at pellet boilers any further, is because it will be impossible for me to get a Silo close to where the boiler is going to. I also have acccess to free or at least very affordable logs and offcuts. A log burner gives me a wider source of fuel while there are few affordable pellet suppliers in Suffolk at the moment.
    • CommentAuthorJohan
    • CommentTimeSep 21st 2007

    I agree with you. The pellet boilers are nice, but if you got access to free/cheap logs and off cuts then a log boiler is better for you. Pellets are currently being imported to the UK as far as I understand. You also get over 90% efficiency with a log boiler with lambda control on it.

    I saw in the other thread you said the lambda control adds £2000? Is that right? That sounds a bit steep to me! £200 would have been more reasonable.

    Having the boiler in the garage sounds alright to me. I think you're better off having the accumulator tank in house, at least that way any heat loss will be useful as heating.
    • CommentAuthoredwinvanek
    • CommentTimeSep 21st 2007
    The difference between a Baxi Solo Inova 30 KW without or with Lambda controls is 2000K, I just got the new pricelist from FBC. To me the added benefits of the controls would be worth more than £200 but not £2000.

    Am I able to use flexible PEX pipe to connect the boiler in the garage to the storage tank in the house, thought the temperature of the water would be too high?
    • CommentAuthortony
    • CommentTimeSep 21st 2007
    Temperatures too high -- steel or copper.
    • CommentAuthoredwinvanek
    • CommentTimeSep 21st 2007
    Thought so. Would building regulations allow the boiler in a conservatory? Ours is extremely big and even closer to our woodsupply than the garage. It also means that I wouldn't need an underground connection the house and I could have the heat store in another room very close to where the current cenral heating boiler is.
    • CommentAuthordieseldogg
    • CommentTimeOct 2nd 2007 edited
    Sorry to be of no use whatsoever,
    I have been pondering installing a gasifying logwood central heating boiler myself, but am bamboozeled & confused by the literature hype, plus NO sales staff here have really any experience.
    Plus the capital costs of the installation ( we have our own inexhaustable wood supply ) against even the current high cost of oil is not attractive, currently £750.00 ( 2250 litres ) heats us for a year.
    I have information on 12 or 15 different makes,
    Atmos locally would probably make most sense
    However subjectively I prefer the Herlt ( Donegal supplier )
    But on balance the Baxi is an established brand name,
    whether or not the oxygen sensor option at the £2000 odd makes sense when we have our own firewood.
    We currently run an 8 kW Morso log stove 24/7 for the 6 or so winter months,
    it is nearly too hot, so like yourself, I was considering fitting a boiler to it for domestic hot water only.
    Then I think the next step is Solar domestic water heating.
    But I cannot decide.
    re pex pipe for boiler water
    should be ok as i know our joiner plumbed his own house 10 or 12 years ago and connected HEP2o straight into an oil boiler, never has failed yet.
    Thanks for that endorsment of the Baxi
    • CommentAuthoredwinvanek
    • CommentTimeOct 22nd 2007
    I have seen the Austrian ATE boilers in operation in Germany and they seem to be very popular there and they apparantly provide component to many other german and Austrian wood boiler suppliers, but they are only supplied with Lambda Control as are the Hertz boilers etc. It is my understanding that the main changes in primary and secondary air control are based on type of wood and humidity and that there are further minor adjustments between start and end of combustion. Can anybody tell me how big the changes in primary and secondary air flow are during the process of one burn. I am still not certain about the benefirs of Lambda control if I can get a well build baxi boiler without at almost half the price.

    Been a while, but thought I would comment re the above.
    Since the circuit board "fried" in our Solarbayer, I have been running it this past winter jury rigged to the mains via 2 time clocks (simply because there were 2 leads)
    One drives the fan at a constant 100%
    the other powers the Laddomat continuiously.
    I can see no difference in operating efficiencies.
    I have got good at estimating the burn time remaining and setting the clocks to within 15 mins.
    only over "cooked" her once this winter.
    Sometimes less could well be more.
    Currently eying up a Herz on the RHPP scheme here in NI
    • CommentAuthorjwd
    • CommentTimeFeb 19th 2013
    I have a Eco Angus (40KW) with a 2400 lt tank heating a 4 bed house with underfloor heating. It works fine and requires 1.5 burns a day atthis time of year - I m in scotland.

    I would say that you pay a lot extra for the big brand names but is the function any better? - the baxi is a good compromise if you can find someone to fit it. It is also worth enuring that the boiler and installer are accredited for RHI as - you never know - there is still a chance they might pay out some money.

    The lower end of the market brands tend to have installers that are cheaper. Ours (Simon Haskins of SandS Microgeneration near Carlisle) was/is an absolute star. He has done loads of other installs in this area and I havent heard a single complaint and lots of very positive comments. I dont work for him in any way btw - just a satisfied customer. A fairly local installer is cheaper (you dont have to pay for their B&B accomodation) and is more on hand should there be a problem.

    Ours is a bit clunky but is very simple. I have looked at more expensive ones and find it hard to justify the additional cost ( windhager, HDG, ETA, Froeling etc) which can be quite considerable. The Hoval one was nice but it would have been a night mare installing it in our boiler room due to the height of the flue outlet. As it is the only flaws I can pick out with ours is that it is easy to forget to close the flap at the back of the boiler and leave the flue fan on. This could have drastic consequences but hasnt as yet. This bypasses the vast amount of the heating tubes in the water jacket and can over heat the flue.The other thing is that there is no flue stat, just one in the water jacket, so that the fan in the boiler continues to run for a while after the fuel has all burnt. I guess it just cools down the boiler quicker.

    I would agree with one of the previous posts - If in doubt oversize your boiler. The more wood you can get in it in one go means the less likely you are to have to refill it. The key feature IMHO is the size of the log chamber - the bigger the better. If I was to do it again I would have the next size up of boiler.

    Also the thermal store gives off a lot of heat. Try and get it inside the building envelope as you may as well lose the heat inside.

    We have had issues with our laddomat ( all sorted very quick by installer)- some posters here have mentioned other brands as being better but I cant comment.

    You do need plenty of log storage and the energy / time to cut it and split it. You really do have to get this side of it organised as you really cant burn wet wood. I view it as exercise - I dont have a gym membership I have lost a little middle-aged spread though!

    I have often wished I had put in a solar system as well as it would save on lighting in the summer and reduce fuel consumption for much of the rest of the year - but funds didnt allow at the time. we did buy a tank with a solar coil in it just in case.

    We also have two DHW coils , one in the bottom of the tank and one in the top, so that cold water flows in the bottom coil and is pre heated by any heat at the bottom before going through another coil at the top. This preserves the high temp water at the top. Some people thought I was crazy to do this but it works as far as I can tell. It hasn't caused any problems anyway.

    It is worth getting a thermal store with more inputs than you need as it gives you flexibility later. Just make sure you think about how you will get it in to wherever it will be - they are large and difficult to handle.

    Hope that helps

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