Getting the most from your solid fueled cooker.

[Kiwi bloke]

I started this answering a problem in an old (& now lost) query.
It was a Bosky cooker not getting up to heat.
My suggestions.....

I am Kiwi who works on cookers and usually work out or solve heating problems. I suggest that its a good idea to get a moisture meter. here in NZ, firewood needs to have 20% or less moisture content.
If a fire is fed wood as fuel, then it does NOT need a grate.
Like "Boboff" mentioned above, a bed of coals would be most helpful so don't be too keen to empty the fire box out completely..
Coal is a dirty word now but that fuel needs a air supply coming up from underneath the grate and through the cavities around the the solid fuel. ie. the coal.

If the cooker isn't getting hot, I'd first suggest checking for air leaks between the fire boxes grate and the very top of the flue. Air should only enter the cooker via the designed openings.

Hard woods used a fuel would be wonderful fuel but even soft woods like pine, poplar or willow will generate really good amounts of heat. Its just that it will burn away more quickly.
I have seen an interesting and very informative web page somewhere, which tells us what kilojoules is in each variety of timber.

When the cooker is cold, I recommend taking out the hot plate and checking all the seals between the Hob and the top surfaces where the flue gases travel towards the flue. There should be NO gaps.

I'd also check the joints around the Oven's sides and the bottom & top panels/plates.

Check to see if there is any cracked or broken plates/panels.

Check that all doors are sealing tightly.
Check for sloppiness or how firm the hinges & locking mechanism is.

Every little gap, allows air in where it shouldn't enter.

FLUE.
Many problems are cause with incorrectly made or installed flues.
If you have a lot of black soot or creosote, then it ain't burning right. If there is creosote, then my biggest guess it that the flue is too cold.
The diameter of them MUST BE in accordance with the manufactures recommendations.
Ideally, they should have no bends in them.
They must be able to keep the heat in the flue gases right to the top edge of the flue.

We in our country, where we can get to minus 4º to 6º Celsius, flues are usually 3 skinned. Some are insulated between the outer skin and the middle skin. (not many are insulated)
An inner flue which is too large for the appliance, will certainly make a cooker get really hot, but the fire wood will disappear quickly & is likely to be wasted.

A flue's size (diameter) is more often than not, governed by the amount of air designed to enter the cooker from down by the grate.
Sometimes there is 2 inlet areas such as in a 355 series Rayburn.
They have a air inlet via a vent in the Ash pit door plus another one that allows air to come in from the side of the cooker and this inlet is also controllable/adjustable via a knob at the rear of the hob.


Going back to the Hot Plate area.... check that the rope seal or tape seal under the Hot Plate, which used to be asbestos but are now generally made of a ceramic material and made into a tape (or rope). These need to be in good nick to stop air being sucked in around the Hot Plate.

If you have signs of smoke residues on the outside of the cooker, usually it will only smoke while the cooker is cold. After it has heated up, the movement of air is reversed, which means its sucking unwanted air into the flue galleries and flue. Therefore, it most likely helping to cool the cooker down.

Some cookers, like the Stanley range of cookers, have a system of allowing secondary combustion air into the top of the fire box. In my opinion, its a great system but that extra ignition is only designed to be within the Fire Box and over the Oven which of course is where the temperatures are wanted to be greatest.

Remember, a fire needs oxygen. The wood is fuel also but its nuttin' without a source of oxygen but too much of it ABOVE the fires solid fuel, mans that it ain't got any other solid fuel source, so it cools the flue gases. Its a dance and the designers have more often than not, worked it out the best they can.

I hope some of that might be informative to you.
Cheers

[Green Aura]

That's very helpful, thanks, Kiwi bloke...and welcome to Ish btw