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Heating and cooling: Accumulator tank taking too long to heat up

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  1.  
    • CommentAuthorArchmoco
    • CommentTimeApr 4th 2014 edited
     
    Can anyone help.

    I've a Broseley evo 26 kw wood burning stove connected to a 1000ltr Akvaterm Solar Plus accumulator tank via a Laddomat 21-60 charging unit.

    The stove boiler has a nominal output to water as 16kw/h, however the output seems to be closer to 5or6kw. I've checked that I am burning the correct wood, good quality kiln dried Birch and Ash with a moisture content of around 3-7% and I weigh the wood to ensure I 'm feeding the stove correctly.

    The laddomat is approx 3m away from the stove and there seems to be 6 bends in the pipe work between the stove and Laddomat and I am wondering if this could be the issue?

    The Laddomat is controlled by a pipe thermostat set at 50 degrees.
    • CommentAuthordaserra
    • CommentTimeApr 4th 2014
     
    More likely manufacturers burning plutonium in the fire to get the stated output. Stove output figures are notoriously inconsistent, like speakers and amps. You'd probably get the stated output with 5 or 6 kilos of matchsticks.
    • CommentAuthorArchmoco
    • CommentTimeApr 4th 2014
     
    Yeah you could be correct but thought its a very big difference. I wonder if anyone else has the same stove?
    • CommentAuthorowlman
    • CommentTimeApr 5th 2014
     
    16kW seems a lot to me for such a relatively small stove. I'd expect that sort of output with a forced air machine the Broseley doesn't seem that sort of stove. I think daserra's right they've been a bit ambitious with the figures. Is your system direct or indirect? Have you asked them, (Broseley technical) to explain?
    • CommentAuthorArchmoco
    • CommentTimeApr 5th 2014
     
    I'm going to give them a call on Monday and have a chat. The photos are deceptive it is a huge stove and 5.6kg of hard wood per hr should give off some heat. The stove has a 150mm air line to the out side, I disconnected it last night to check In case it was blocked but there is a good rush of air going through it. I would be more happy if a realistic figure was say 10kw but 5 or 6kw seams to be mean when manual says 15.8 kw. It is the only stove that gets the RHI grant so I'm sure others have bought one, to be fair the stove only cost £2700 from stoves online, and I got the £2500 RHI grant.
    • CommentAuthorCWatters
    • CommentTimeApr 6th 2014
     
    Did you calculate the 5-6kW from the warm up time of the store? Perhaps post your figures so we can check them?
    • CommentAuthorArchmoco
    • CommentTimeApr 6th 2014
     
    Thanks very much;
    No I waited about 30mins until the temp in the rank started to rise.

    Figures as follows, time, temp at top of tank, temp at bottom.

    Sat evening
    20:41. 53.7. 46.4
    21:12. 53.7. 46.3

    21:14. 53.8. 46.5
    21:33. 57.5. 48.6
    22:06. 64.1. 50.6
    22:19. 65.9. 51.3


    Friday evening
    16:28. 60.2. 56.8
    16:49. 60.1. 56.8
    17:15. 64.6. 57.4
    17:51. 66.8. 57.8
    19:31. 69.1. 62.2


    I've more recorded but these are very recent, I,ve more figure taken over a longer period, however my aim is to do as quick burn as possible.
    • CommentAuthorArchmoco
    • CommentTimeApr 7th 2014
     
    I have identified one issue with the stove. The early model came with a smaller 100mm exterior air box conection, which has now been upgrade to 150mm. My air line in under the floor screed is 100mm. The spare part is cheap, but its going to be a pain and look crap with a 150mm pipe boxed out above floor level.
    • CommentAuthordaserra
    • CommentTimeApr 7th 2014
     
    My 12KW has a 100mm air supply if that helps.
    • CommentAuthorArchmoco
    • CommentTimeApr 7th 2014
     
    to be honest my inlet was just flush with the wall at at ground level, I've altered the inlet with some drainage pipe to stick it up and I've used a 90degree section to create an air scoop arrangement, I'll give it a try next time the stove is lit. Failing that I'll look at 150 duct boxed in and if I have to I'll stud the wall out.
    • CommentAuthordaserra
    • CommentTimeApr 7th 2014
     
    Just a thought but I've had trouble with a new stove that had 10mm holes drilled in a 10mm sheet of steel for a grate. In use the holes block up after a few hours and I can't get the stove to produce until I poke the holes through from underneath.
    • CommentAuthorArchmoco
    • CommentTimeApr 7th 2014
     
    Is yours a wood burning or multi-fuel? the Broseley is a pure wood burning so there should be no air from below, but I'll check the manual and see.

    many thanks
    • CommentAuthordaserra
    • CommentTimeApr 7th 2014
     
    Mines wood burning only (Woodfire F12). Does yours not have any primary air from below? Your max rating is probably with the primary air fully open if it has one.
    • CommentAuthorArchmoco
    • CommentTimeApr 7th 2014
     
    I think it has just air from above, holes at high level. I thought wood was only from above as more efficient to burn on a bed of ash. Must have a look at the F12 stove.

    Anyway, I've altered the air supply, I'm going to set the laddomat pump speed to 2 and I have given the boiler a good clean so I'll try again tomorrow evening and see what if any difference it has made
    • CommentAuthordaserra
    • CommentTimeApr 8th 2014
     
    As far as I am aware (I am far from an expert) you have primary combustion with air from below and then the gases driven off are burnt in secondary combustion with air from above. You control overall power output with the primary air control. I know the blocking issue on my WBS causes the fire to die down drastically and the glass soots up and the buffer stops heating up. I then poke the holes through and it flares up to a raging fire again (which is the type of fire they use to measure the KW output usually). The primary air on ine is supplied through a variable grill IN THE ASH BOX which then passes through the grate, hence the blocking issue when the holes in the grate are blocked.
    • CommentAuthorCWatters
    • CommentTimeApr 12th 2014 edited
     

    Sat evening
    20:41. 53.7. 46.4
    21:12. 53.7. 46.3
    21:14. 53.8. 46.5
    21:33. 57.5. 48.6
    22:06. 64.1. 50.6
    22:19. 65.9. 51.3
    .

    Where are the stats mounted? Is the top stat around 1/3rd of the way down and the bottom one a 1/3rd of the way up?

    The above looks like no change for the first 90 mins then perhaps 10C an hour for the top third (?) of the tank.

    On that basis the energy in works out at about..

    333(Kg) * 4.2(kJ/kgK) * 10(K) = 14000 KJ

    Power = energy(J)/time(S)

    = 14,000,000/ 60 * 60
    = 4kW

    But this could be miles out if you have a nice layer of 90C water at the very top of the tank.
    • CommentAuthorArchmoco
    • CommentTimeApr 14th 2014
     
    Yes stats 1/3 down and up.

    I'm having mixed results getting stove pre heated best is 30 mins, but usually 45-60 mins

    but I've managed to get the stove output up to about 11/12kw I think it was a multitude of things.
    I gave the boiler element a good clean with a wire brush, altered the air line, ensured that I was burning only kiln dried wood and measured each loadings, however I am loading more like every 30 mins, but the main thing is I can get the store to full temp quite quickly now. I'm taking the offer from family and friends to remove fallen trees, very time consuming however by the end of the summer I should have quite a stock pile of fuel.

    I think to get the text book 16 kw I would need to upgrade the airline to 150mm.
  18.  
    "It is the only stove that gets the RHI grant so I'm sure others have bought one, to be fair the stove only cost £2700 from stoves online, and I got the £2500 RHI grant."

    The approved appliance spreadsheet says that it's not approved, so I'm wondering how you got the grant?
    • CommentAuthorArchmoco
    • CommentTimeApr 15th 2014 edited
     
    I got it back in December 2012, I believe from the 1st April 2014 it has been taken off the list as it does not meet the Co2 emissions, however they honored previously agreed appliances and as such we got the grant

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