Archive for Over the Gate Join in for a friendly chat over the gate about home and country matters. (Nominated Charity The British Heart Foundation)
 


       Over the Gate Forum Index -> All Things Mechanical
diggerpete1961

Calorific Value of Wood vs Coal

I have been talking to Arada about their stove outputs. Take for example their 5 Kw model. They say:- the 5 Kw is a 'peak' rating taken using coal (as are all thier tests) & to disrate to 85% of this for a long stove life, thus the 5 Kw becomes a 4.2 Kw max 'continuous' output. (on coal)
They say if I burn wood the max output will disrate automatically to this as wood has slightly less heat output.
This site   http://www.firewood.co.uk/heating-qualities/   says weight for weight wood has just under half the the heat output of coal, & that all wood has much the same heat output by weight (but its density or volume to produce a given weight varies quite a bit - this last bit is without doubt true.)
A 60 yr old book on steam piledriving plant says the same of wood vs coal heat output
So if this is true does my 5 Kw example stove become 2.5 Kw when burning wood ? I want to know because an 'add in' backboiler is offered but at 2.5 Kw output there is no heat to spare for this as all heat would be needed for just the downstairs here. I am planning anyway to run as a dry stove for at least this winter. Just wondered who is right - or is this an impossible question to answer in real word conditions???
redbelly

This is a question which i have pondered a bit as I rely on wood for space heating, hot water and most cooking.
The thing that occurs to me is that time is also a factor. In theory if wood has say half the heat value of coal you can obtain the same heat output by burning twice the the quantity in a given period without subjecting the stove to any greater heat load.
I realize that in practice there is a limit to the volume of fuel that can be burnt in a given period of time.
I also find that lighter types of wood, being more volatile require more air to burn cleanly than more dense wood and thus have more tendency to burn out metal components (in the same way as an oxy torch burns steel).
sod

Redbelly you are right, digger part of what you say is right    which part?? Well it all same per tonne not volumn but when you load your stove you are looking at volumn as in firebox size    We usewood in a coal range stove as it is much cheaper, most is pine so soft wood lot of fast heat therefore need to fill more often, harder wood same heat over longer time same as closing down for the night to burn through you only get small heat all night which so many people can't understand A test we did once was to boil kettle of water with wood and then coal found little time difference just had to refill wood. Don't know if this helps.
darkbrowneggs

I have an old wood burner I have used for years.  It was alway pretty ineffective, and I have found the easiest way to run it is just part close the damper and keep the doors wide open, so basically it is an open fire in a box

My question is - I have some coal, could I put this on at night to keep the fire in, or would it
(a) burn the bottom out - there are no coal bars,
or
(b) just not burn?
sod

darkbrowneggs wrote:
I have an old wood burner I have used for years.  It was alway pretty ineffective, and I have found the easiest way to run it is just part close the damper and keep the doors wide open, so basically it is an open fire in a box

My question is - I have some coal, could I put this on at night to keep the fire in, or would it
(a) burn the bottom out - there are no coal bars,
or
(b) just not burn?


I think it would be hard to burn without a grate to let air through. We took grate out of our coal burner to make it burn wood better but keep it to put back when on rear times we burn coal IMHO plus heat with no heavy steel could be a problem as you asked.
OUr one has gaps around doors   so gets plenty of air to burn good
darkbrowneggs

Thanks - probably as I thought  

       Over the Gate Forum Index -> All Things Mechanical
Page 1 of 1
Create your own free forum | Buy a domain to use with your forum