People occasionally have questions on stoves and firewood. Here's some general info:
What’s a suitable place for a stove and what size of stove should I buy?
A stove placed in the middle of a room naturally transfers convectional heat more evenly. This is an interior design situation which doesn’t suit everyone but it’s worth thinking about where your stove is going to be placed in relation to the area you want it to heat. Convectional air heat transfer is a lot cheaper than expensive plumbing. As a rule of thumb you need one kw per 14 cubic meters of space to create 21 degrees of living space.
What type of stove should I buy and how much should I spend on it?
The quality and type of the stove you buy is a big decision. If radiators are a major concern perhaps you should be looking at a solid fuel boiler instead such as http://www.econboilers.com . The quality of a stove pays for itself in fuel consumption and the control you have over the energy produced. For example, if stove (a) costs 800 euro and stove (b) costs 1300 euro, the 500 euro difference over a 24 months period of fuel used (and the control over the energy produced) will cancel the extra cost out. Researching the myriads of designs available from inserts to classic designs is part of the course but when investing, no matter what design you choose, buy the best you can afford as the pay back time is a lot shorter than you’d think. Consideration to whether you want a multi-fuel stove or wood burning stove is worth a lot of thought too because a wood stove normally doesn’t have a grate. Burning timber on ashes is a really good idea because the timber burns slower and better.
What other considerations are there when buying a stove?
There is little point in buying a high quality stove if your flue/chimney is not correctly installed or dirty. Most countries have guidelines and safety regulations online. A few general pointers are (a) Flue gas needs to be hot to draw, (b) the top of the chimney needs to be higher than the highest point of your roof to help stop back draft, (c) Good access to the flue system makes cleaning a lot easier and cheaper. A certified chimney sweep can clean a chimney but also has a lot of experience if advice is needed.
How do I control the fire in a stove?
To control a stove you use air baffles. These are the little air valve devices that allow air flow into the burn chamber. Some baffles use heat springs and have dials, some have levers, others have have handles that pull in and out. Stoves can have a number of these and it’s essential to check the manual to see their purpose. Usually there are two, one that opens air into the bottom of the burn chamber and another to open air into the top(secondaryburn/airwash). When you light a stove from cold it’s a good idea to have all valves open. This gives lots of air to the fire and gets the gas in the chimney hot to create a good draw. From there you can turn down/off the primary airflow to encourage secondary burn. This occurs with firewood when all the moisture gases have been burnt off and the temperature is high enough to burn the hydrocarbon gases. This creates a slow burning hot stove as charcoal is being produced.
Why buy softwood or hardwood?
There are two main categories of firewood, softwood and hardwood. You can burn both. Hardwood tends to burn for a longer period and burns at a high temperature. Softwood is not recommended in open fires as it is liable to spit a lot. It takes longer to season than hardwood, burns at a high temperature but at a more rapid pace. Softwood is nearly always cheaper to buy and is a good option if economy is important and you only light a fire occasionally. Alternatively, you can use a mix of hardwood and softwood.
What’s the best hardwood timber to burn?
All hardwoods have different characteristics in regard to how they burn. In Ireland Ash is used a lot while in France ,for instance, Oak is used. Is one better than the other? I think it really boils down to what you’re used to and also what works in regards to your stove and how you operate it.
Can I burn wet firewood?
All timber needs to be dry before it can be burnt. Not because it will not burn, it will but very badly. If you burn wet timber/fuel most of the combustion energy is wasted removing moisture and wet timber/fuel can also lead to chimney/flue problems.
How dry does firewood need to be?
Ideally at some stage in the seasoning/drying cycle it has been at a 20% (or less) moisture level.
Do I have to burn kiln dried timber and why do people produce it?
Timber does not have to be kiln dried to be burnt in a fire. The two main reasons why firewood is kiln dried are
- To create a uniform product
- To reduce the time and amount of stored stock needed to turn around for sale as compared to air-dried firewood (which could need anything up to 16 months).
If you want to buy kiln dried timber see if you can get solar passively dried timber or similar. It’s a lot more environmentally friendly and makes more sense. Also worth noting is when you buy any dried timber that may have been reduced down to 14% moisture at some stage, it can naturally adopt moisture afterwards. This is hard to avoid in a damp country like Ireland.