Efficient burning

[teepeeat]

I think that stoking the fire is always a compromise as opening up and reloading will always affect the temps/balance of what is going on, but is of course a necessity. The more wood you put in at any one time, the greater the effect - ie there is more wood to get up to temperature, but when it does there will be a lot of energy so I am guessing there will be greater fluctuations and extremes in Big J's case.

 

Cornish Wood Burner's chip boiler I guess relies on automatic fuel feeding, but would indicate a little and often approach where the manufacturers of my stove have moderated that approach for practical reasons related to manual feeding of logs.

 

As Stereo has said, and my experience backs up, a half load burns for almost as long as a full load, meaning the extra energy is just going up the flue.

Having a boiler attached, I guess there is also the rate of transfer of energy to consider, which will have limits and excess energy again just flies by up the flue.

My stove is insulated to the extent that I can put my hand on the side when it is roaring away, so burning more does not translate to more heat to the room to any large degree as the only transfer to the room is via the door, but then it is designed to put the majority of the heat to the boiler.

 

The OP was looking at achieving fuel efficiency, This is going to vary with different set ups, however I think the general trend for efficiency is to feed little and often depending on your setup as regards heat transfer to a boiler or the room.

 

For the record Big J, my 8kw stove does the hot water and heating for a 200m2 house. It is located in the upstairs open plan living area and the heating in that space has never to my knowledge kicked in, although this is more to do with the levels of insulation we have. I can burn for an hour in the evening and then come upstairs the next morning and it will still be 18-20 deg C in the space, although this is helped by the underfloor heating from the bedrooms down stairs migrating up. Bedroom thermostats set around 15-16 deg C normally.

Edited January 1, 2015 by teepeeat

[Big J]

For the record Big J, my 8kw stove does the hot water and heating for a 200m2 house. It is located in the upstairs open plan living area and the heating in that space has never to my knowledge kicked in, although this is more to do with the levels of insulation we have. I can burn for an hour in the evening and then come upstairs the next morning and it will still be 18-20 deg C in the space, although this is helped by the underfloor heating from the bedrooms down stairs migrating up. Bedroom thermostats set around 15-16 deg C normally.

 

With your insulation you are clearly a lucky chap (or indeed a wise one, having spent the money on that!).

 

We have a normally orientated (ie, stove and living room downstairs) 127 sq m 230 year old house, which is mainly single glazed sash and cash windows downstairs and no insulation anywhere except for the roof. I don't have any issues keeping it warm (and it's warmer than our old house) but we do use a fair bit of wood.

 

Regarding half load versus full, I find that it won't sit at the desired temperature (550f) for anywhere near as long on a half load. If it's mild outside (as it is today at 8c), I'll perhaps put on a log or two less, but I generally prefer to burn hotter. I have an unlimited supply of wood though.