the further tales of pellet fired boilers

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  • the further tales of pellet fired boilers
  • Premier Icon MrOvershoot
    Subscriber

    Stoner – Member
    and another thanks to MrOvershoot for the tips on the Storz Couplings. The websites out there are useless for any guidance on how to install them.

    Bloody expensive bits though – £150.

    Glad to see you have it sorted, Yep they are a bit spendy but as long as you don’t do like our tanker drivers and smash them into walls they will last.

    Re the dust, what is the moisture level of the pellet dust & what Kst is quoted?
    Static is not necessarily a problem as even the industry I work in where flour dust has a higher Kst than Propane/Butane its not possible to generate enough J of energy from static to ignite flour.

    Though bear in mind wood & paper account for the largest number of explosions in UK industries

    Bear
    Member

    Also bear in mind how much this store has cost you and how much the pellets inside it will have cost. Much more than another store coupling…

    Stoner
    Member

    wood pellets are nominally around 5%-10% moisture.
    They dont have a quoted Kst figure as “dust” is not their normal form, in fact the ones I use (Verdo, highly recommend them Bear) have a mechanical durability above 97.5%.

    But most wood/paper fires are not from static sources are they?

    Bear
    Member

    It’s bloody dusty when they blow them believe me!

    Marko
    Member

    Great stuff, Stoner.

    I have some rubber matting from a stable block you can have, if you are interested? I’m just south of Monmouth, so if you are passing it may be worth collecting?
    Hth
    Marko

    Stoner
    Member

    cheers Marko – I know that stuff (S-i-L uses it) but I think it’s a bit to stiff. I reckon something with a bit more give is needed. Trying to think why a hanging fabric wouldnt do it….

    Just picked up a flymesh slatted vent to fit later to allow air out when the pellets are being pumped in.

    Bear
    Member

    One thing I learnt today was don’t go climbing in your pellet store especially for 4 weeks after delivery

    Stoner
    Member

    ha. Used to love playing in the corn stores…

    When I first started working on the farm, I asked why the access hatches on the top of the grain silos were padlocked. The gaffer said it wasnt for when it was full of wheat of barley, but when full of linseed. If you fell in, you sank to the bottom and no doggy paddle or breast stroke would keep you up.

    Bear
    Member

    Not for that reason although it is a good one. Apparently they can release carbon monoxide and there has been two fatalities in northern island I believe

    Stoner
    Member

    the atmosphere inside can become oxygen depleted

    typical HSE, no info on how the phenomenon occurs.

    But interesting to know.
    Might be worth putting a gravity vent in for CO

    Bear
    Member

    Because they don’t actually know why the build up occurs but it does and I assume it has done on other occasions where they have measured it.
    The line of thinking is to do with friction and heat build up causing the pellets to release the gas. Think of the pellets being fired down a hose and also moving about in delivery tanker. Have you got a co alarm in your boiler room too as that is a requirement.

    Stoner
    Member

    a pre Oct-2010 installation, so wasnt a requirement then.
    I might get round to picking one up sometime, but the room is well vented and there’s even a floor level vent that heavy gases can use.

    Premier Icon bruneep
    Subscriber

    I might get round to picking one up sometime

    < dad mode>

    Means you won’t. Having recently been at a fatality caused by co poisoning, they are cheap way of saving not just your life but also your families.

    < ends dad mode>

    The amount you have spent a co alarm is pennies.

    Stoner
    Member

    😳

    OK Dad

    fatality caused by co poisoning

    Blocked balanced flue on gas combi in a bedroom cupboard?
    Bit different from a draughty boiler room…
    but point taken.

    TooTall
    Member

    Question for the pellet boiler types:

    How do they compare overall to the log wood boilers made by the likes of HDG? I only ask because I like the idea of minimum processing from tree to fuel that the log boiler brings. I understand the potential reduction in convenience, but if I wanted to really reduce the reliance upon the transport system (and oil) for heating, a log boiler would seem a good answer.

    Stoner
    Member

    TooTall – Im in the foruntate position of being able to use both pellet and log fuel sources:

    Pellets burn in the right, logs can be loaded in the chamber to the left.

    Logs are slightly less efficient as a fuel source, simply because they are rarely kiln dried down to <10% like pellets. The calorific value of the wood itself is the same though (and strangely enough consistent across tree species too). Normally log burners are less efficient than pellets, but I see the HDG ones are very efficient and match their pellet boiler performance. Bloody ought to make the tea too at £9k+ 😉

    You can get similarly sized ones on eBay (also MCS cert) for £2.4k
    http://www.ebay.co.uk/itm/280837307602

    Geoffj of these ‘ere parts was also thinking along the lines of fuel independance and I think went for a slightly different approach matching a stove back boiler with a thermal store via a load charger.

    You’d have to be pretty committed to go for log boiler as a your main energy source, as you would have no automated “call for” heat option (unless you went for an electric immersion heater in your tank, bad mmmkay), you’d have to keep an eye on your water temps and go and light a fire, or stoke an existing one as and when necc. Might be a pain for your wife, for example, if you were away for a few days.

    It would operate better as an augmentation to say an existing gas or oil boiler that you could fall back on for convenience. Like geoff’s.

    And a thermal store with a solar thermal array would be a sensible addition too.

    As for “convenience”, I quite like making a log fire in the morning. Takes me about 10-15 minutes over my breakfast coffee to get it started, loaded and roaring before I can shut it down and leave it to it’s own devices for 3-4 hours. One full burn of good wood should give me about 50kWh of energy according to the manual. Which is enough to do the DHW for the day (if no solar). To cover the UFH too, Id need to re-load the furnace maybe with another one or two loads during the day. (just means throwing a few armfuls of logs in and shutting the vent back to trickle). Then if the heating needs a top up overnight, the pellet boiler is called on to fire up and it will throw another 50kWh in (this is the middle of winter we’re talking here. At the moment, we’re using around 50-60kWh a day on DHW. When the sun disappears for April, I’ll turn the pellet boiler back on and it will deal with the DHW need. Doubt Ill turn the heating back on again though now)

    TooTall
    Member

    Cheers, Stoner. I’m just looking at things as they cross my path and tucking away the concepts for a year or two. I am planning a new start somewhere else in a year or so and balancing off ideas of resilience against convenience and seeing where that could put my ideas.

    I’m off to see a new small biomass plant tomorrow but I doubt I’ll have one at home! 😀

    Bear
    Member

    There is a log boiler with pellet attached that automatically swaps when log burn finished I believe. It might be an HDG but don’t swear by that.
    So much stuff out there it is amazing.

    Premier Icon ourmaninthenorth
    Subscriber

    Stoner – if stable matting is too heavy, consider the shockpad from an old astroturf. Friend of a colleague has East Grinstead’s old pitch(es) and is flogging the stuff on ebay as stable matting. No idea, but might do the job.

    Oh, and fascinating stuff all – keep it up.

    Bear
    Member

    Try to find old supermarket conveyor belt according to the guy doing the training it is ideal apparently

    Stoner
    Member

    I found some synthetic mesh material which I’ve stapled across the back of the tank like a trampoline. I would have thought high density rubber would still be too hard to prevent pellets. breaking.

    Premier Icon miketually
    Subscriber

    Seeing the photo of Stoner’s boiler above is the first time it’s occurred to me to lag the hot water pipes in the understairs cupboard that our combi boiler sits in.

    I’ll add that to the list.

    Bear
    Member

    They shouldn’t be blown in at that sort of velocity. The mat should start to curve after a while creating more of a slide effect.

    mrgibbons
    Member

    Stoner, Bear,

    Interesting analogies on the padlocks on grain silos…can I offer different explanations? I worked at Camgrain for 3 years, silos are damn dangerous places. What Stoner says about linseed is totally true, it’s like quicksand given the slipperyness of the grains. I routinely would hand sample outgoing/incoming truck loads for ergot/pests etc when our vacuum sampler would break down, but linseed…not on your nelly.

    I have *never* heard of the CO build up theory, and I can’t ever recall it featuring in any safety protocol, but I can well believe it. Usually you keep the hatches locked for several reasons. 1 – Pests, 2 – Children/teenagers playing 3 – Explosion risk. Cleaning those silos (upto 5000 ton) out with quick scaffold and yard brushes was damn sketchy work at the best of times, and looking back on it, we must have been mad, but the money was good and the work physical. Respirators are an absolute must.

    Also hatches are kept locked because you can get what are called ‘grain walls’ i.e. if you’re drying with aerators grain/barley in a silo, and then run what is called a ‘sweep’ to say…transfer grains to the dryers, (it’s a big auger running around a central point that sucks grain down to a chute) you can get unstable points in the pile that can collapse, i.e. the grain looks solid enough to stand on, but in reality, it’s just overly moist and there are hollows underneath that can collapse…

    In short, you keep them locked as they can kill, perhaps in a silage silo you may get CO build up, but I’d be surprised in a grain silo unless it was put away very wet indeed.

    Anyway, back on topic, this wood boiler stuff is epic! Keep it up 🙂

    Stoner
    Member

    interesting stuff mrgibbons.

    as for the pellet store, it got it’s first delivery yesterday.

    1700Kg. It could probably take a little more but Id rather not overdo it and have a 20m pipe full of pellets that needed blowing loose somewhere when the tank backs up. Actually 25m of pipe from the gateway to the store.

    Was dusty as you say, Bear, but since the tank is outdoors it wasnt a problem and a wet rag over the vent caught most of it. A quick sweep up afterwards did the rest.

    Got my man to “top up” my neighbours 6+ ton bag with 3tons to the brim. Since my neighbour burns pellets faster than me (smaller solar array and I will be using logs a lot of the time) it means we can get 1.7t and 3t++ delivered each time to make it worth the delivery guys while. I can highly recommend him if you are looking for a delivery guy Bear. Based in Leicestershire and delivers Verdo pellets from the Mill at Andover all over the country.

    He has a great wagon. It does have an extract fan as well if your tank has the additional fitting for it.

    Bear
    Member

    Nice work Stoner – how much per tonne?

    Premier Icon paul4stones
    Subscriber

    Here’s our Windhager going in.


    Berluddy complicated and it took the installer ages to get it sorted, in the end the chap from Windhager had to come up and sort it – I wouldn’t be surprised if it was a crossed wire or something. Anyway, now it’s working it’s fab. We’re using about 8 – 10 bags a week depending on the weather, heating and DHW. Agree about the waste and non-recycleable plastic bags which seems all wrong.

    One thing that’s changed is the separation of the zones in the house. Not sure whether it’s because of the mixing system to vary the temps in the rads but there seems to be spill over between zones. One zone covers a part of the house with lots of windows which gets hot when the sun shines – slightly frustrating that the rads get warm in there even when the ‘stat says no heating needed. Generally I’m very impressed by how ‘clever’ the system is. Previously, when the heating was either on or off, cold days were obvious because the house was colder. Now it’s sometimes a surprise when you go out and find it’s really cold!

    May look into sharing loose pellets with locals – we couldn’t store more than 1.5 tonnes. Or we might increase our olive consumption 😉

    Bear
    Member

    Paul – looks nice, did Paul from Windhager sort you out?

    Personally I found the install I have done not too bad, BUT I did go to WIndhager for a day to get an idea of the product, also had to call them a couple of times when instructions weren’t quite clear. Other than that it was good fun to install.

    And where are you in the country? If my second install comes off am hoping to put together bulk orders for my customers. Have already talked to pellet supplier and he will give them a better price if they can deliver into one area at a time.

    Bear
    Member

    Oh, and if you share loose pellets they MUST be kept very dry.

    Premier Icon paul4stones
    Subscriber

    We’re in Northumberland and yes, Paul had to come up to sort it.

    Initially the problem seemed to be that we only wanted 17.5C on the stats, partly because of the location of the stat and partly because we don’t like it too hot. Unfortunately this puts the boiler into ‘setback’ mode. Took a while to work that out.

    This was the first install of the new control system (MES+?) and it’s quite different from the older one. W’hag haven’t even got a diagnostic module for it yet.

    Stoner
    Member

    My last bagged delivery was £276/t + VAT = £289/t

    I think Robert mentioned £230/t (+ VAT Im assuming) for bulk delivery but I havent got the invoice yet. So that would be £241.50, or 16% cheaper.

    Which is almost exactly 5p/kWh before losses @ 4.8kWh/Kg.
    Oil currently c.60p a litre, = 6p/kWh @ 10kWh/L

    Woo, and indeed, hoo.

    PS, nice windhager paul – after a while the pellet bags will piss you off, and you’ll be tinkering with your own store 🙂

    We’re using about 8 – 10 bags a week

    wait till a proper cold spell, you’ll be surprised how much fuel is need to keep even a well insulated house warm.

    In the really cold period at the end of 2010 with sustained sub zero average temperatures, average energy consumption was in the range of 125-150 kWh a day to maintain 16-18degs in the house (we work from home)
    a bag is a round 50kWh, so 2-3 bags a day when it’s really parky. This time of year Im using around 1.2 bags a day on average for DHW and a bit of radiators upstairs at the boy’s bedtime.
    (ignoring the spikes which are just measurement issues)

    Premier Icon paul4stones
    Subscriber

    Ours is cheaper though – £220/t 🙂

    Noticed a big difference this last week (10+ bags) compared with the week before (<8 bags)

    Stoner
    Member

    PS Interestingly, my SAP suggests a DER of 28,000 kWh pa for Heating and DHW. My TER is 31,000 kWh pa, so indicates 10% below target, which isnt that good, but OK I think. At 232 m2, that’s about 120 kWh/m2/a where a “typical” house is around 200 kWh/m2/a. So 40% saving on a “typical” detached house, and a further 16% saving on the cost of oil since at 5p/kWh for pellets, thats £1,400 a year, (£250 ish less than for oil)

    or to put another way, £1,400 a year at 6p/kWh and 200kWh/m2/pa would maintain a house of only 116m2 compared to our 232m2.

    Maths. Love it.

    Stoner
    Member

    £220/t

    bastard.

    is that w or w/o VAT?

    Premier Icon paul4stones
    Subscriber

    w

    We need to run at least a year to get sense of it. It’s only been working properly for about 8 weeks and we’ve used about a tonne since then. We used to use 2000+ litres of oil in a year. Except last year but we were cold a used electric for the DHW.

    Premier Icon wwaswas
    Subscriber

    Do you get different amounts of energy out of different batches of wood or is it fairly consistent (assuming same moisture content)?

    Edukator
    Member

    wait till a proper cold spell, you’ll be surprised how much fuel is need to keep even a well insulated house warm.

    In the really cold period at the end of 2010 with sustained sub zero average temperatures, average energy consumption was in the range of 125-150 kWh a day to maintain 16-18degs in the house (we work from home)

    Not wishing to be funny, Stoner, but those figures say your house isn’t well insulated. A passive house project in Alsace has no heating system at all and a year low of 15°C was recorded by the occupiers. That’s in a region colder than the UK though it’s warmer down here in the SW. Passive houses often do better than 15kW/m2/year.

    We’ve got through 2m3 of soft wood this Winter, about 3000kW or 20kW a day on average for 16-20°C. I’m still improving the insulation so each year is a bit better. We’ll probably only light the stove another three or four times this heating season. The sun is currently warming the room nicely: 17.9 this morning and 19.2 now, there’s fresh snow at 1000m.

    Stoner
    Member

    wood has a consistent energy density as lignin is lignin. So Wood has a net calorific value (NCV Dry) of 18.3 MJ/Kg. Thats for “Dry” and they mean really dry. Oatmeal 17MJ/Kg, Straw 15 etc.

    the calculation to determine net energy after moisture is:

    NCV Dry x (1-Moisture %) – (2.443 x Moisture %)

    so

    18.3 x (1-5%) – (2.443 x 5%))

    18.3 x 0.95 – 0.122

    =17.263 MJ/Kg, which when converted to kWh by dividing by 3.6 gives

    4.8kWh

    Stoner
    Member

    but those figures say your house isn’t well insulated. A passive house project in Alsace has no heating system at all

    Ed, a passivhaus isnt just insulated its leak free. Mine is a converted barn. It beats all current reg targets and is relatively speaking well insulatated. Passivhaus targets are completely unreasonable for 18th Century barn conversions without throwing hideous amounts of money at it.

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