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Author Topic: Okofen vs Ponast?  (Read 4395 times)
catkin
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« on: July 08, 2012, 05:53:21 PM »

My husband and I have contacted quite a few biomass installers in our area (NW) and the two with the most understandable reps who seem to understand what we would like to achieve in the long run, have come in at around the same price for the boiler install. 

Does anyone know which would be the best system to go for though?  One has a Ponast with 250kg hopper, and the other has an OkoFen with 130kg hopper.  The Ponast would be installed in the outhouse (not attached to the house) and the OkoFen would be in the cellar - we gave the installers free rein to decide where they thought best to site the boiler and they had differing opinions (as seems always to be the way!).  I think the location and refill time either way will be fine for us, but I don't know which would be classified as the 'best' boiler or even whether either of those are really any good. 

I have been searchign around on the internet for weeks regarding this, but being totally non-technically minded, I am feeling quite at a loss, but need to make a decision soon, as we can't submit our paperwork to the listed buildings folks until we have sorted out what we would actually like to install!  We are installing into a 3 bed semi cottage with solid stone / rubble walls and no double glazing etc.  We can't install under floor heating because of the various flooring types thorughout the building and bedrock etc so will be going for radiators ... We will have one dry woodburner and one open fire too.

Any thoughts / assistance on how to make a decision like this would be much appreciated!!
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dhaslam
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« Reply #1 on: July 09, 2012, 10:11:22 AM »

The most important thing is the reliability  of the suppliers.      In Ireland there  was a high percentage grant for  pellet stoves and boilers a few years ago.  Most of them have failed and with them their suppliers, aided by withdrawal of grants and the building slump.       The problems are  electric motors plus  electronic controls  in close proximity to very high temperatures,  variable quality of  fuel and  so far relatively low volumes of installations.   
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DHW 250 litre cylinder  60 X 47mm tubes
Heating  180,000 litre straw insulated seasonal store, 90X58mm tubes + 7 sqm flat collectors, 1 kW VAWT, 3 kW heatpump plus Walltherm gasifying stove
catkin
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« Reply #2 on: July 09, 2012, 01:09:42 PM »

the OkoFen supplier seems to have a good reputation, I have met someone else who had him install his boiler over three years ago and really rates his service and it is all that he does, no plumbing or anything else on the side, no gas, no oil so his livlihood is all based on biomass which I thought was probably a good thing?  I know he has put a system in his own current property and had one in his previous house too, and is very confident in his system.  Is OkoFen counted as a good make?  Just don't want to discover that we have put in the reliant robin (no offence as cool in its own right!) instead of the rolls royce but spent the same by error of judgement and lack of knowledge...
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catkin
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« Reply #3 on: July 14, 2012, 10:15:44 PM »

An additional query that I forgot to ask previously is whether or not a heat store is really considered an essential with a pellet boiler?  We have had some installers take it for granted that we will have one, and others just say that there will be a standard hot water tank ... I am very confused.
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dhaslam
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« Reply #4 on: July 14, 2012, 11:59:11 PM »

Some   pellet stoves  show output levels  and pellet consumption  that aren't linear and the efficiency can be quite low at  lower outputs.    Stand alone pellet boilers are  probably  less affected by being run at less than optimum  output  but it could amount to  quite a difference.    Also there is the question of meeting peak demand, if   water needs to be heated in the morning at the same time as  a high space heating demand then the store will help  by allowing more output than the boiler capacity for a time even as well as allowing the stove to be smaller.   A third reason might be  that in a situation where the  boiler fails there would be some  backup heat.    A store could be heated  by immersion slowly over a long period and act as a viable backup while the boiler is being repaired.   
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DHW 250 litre cylinder  60 X 47mm tubes
Heating  180,000 litre straw insulated seasonal store, 90X58mm tubes + 7 sqm flat collectors, 1 kW VAWT, 3 kW heatpump plus Walltherm gasifying stove
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