Cottage Wood Burners

woodburnerBookings and net profit can be substantially improved with the addition of extras.  The aim of this advice is to lay out some of the pros and cons and provide some useful information about their use and management once installed.

Wood burners can be scaled depending on the size of a cottage and can also be used as supplementary hot water providers for radiators. If you can get sufficient extra bookings or manage to raise rates sufficiently then extras will pay for themselves.

Buying the right product at the right price is important.  Wood burners can appear inexpensive but the lower cost ones are often difficult to run, more dirty and frequently less stylish.  In the hands of inexperienced guests, they can stack up a load of problems for cottage owners.  The price difference between a high quality burner and what appears to be an economical purchase can end up costing owners hugely more over a few years.  Installation costs can run into the thousands and it is common for installation companies to insist that they also supply the burner; prices vary significantly so getting a few quotes is strongly advised.  However it is far from impossible to buy the burner and find someone who will fit it although it is important to be certain they can provide the HETAS or any locally applicable certificate on completion.

 

Purchase

Make sure that you have an adequate flue or can install a modern wood burner flue before buying.  There is a good choice of wood burners on the market but some installers will not be of assistance if they do not also supply a wood burner so if you want to buy separately, line up installers before buying.  The ease of maintenance, robustness and style vary significantly between burners.  It was possible, not so long ago, to purchase a well designed, stylish burner suffering from a critical fault of using too little steel.  Some burners did not stand up to high usage and did not last long.  Some less expensive burners are robust but are turn out to be more difficult to operate and control than more costly ones.

With our wood burner we replaced the fire bricks which were insufficient with mouldable fire brick.  We removed the remains of the old fire brick and applied the mixture shaping it to inner wall of the burning chamber and then ran the burner at a low temperature before running it in the usual way to fire the mixture.  The result was firebrick perfectly fitted to our burner and it radically improved its performance. Some burners are caste iron and others are made from steel.  Caste iron can crack if overheated or if there is an impurity in the metal.  If this happens for a burner more than two or three years old it is very difficult, if not impossible, to dismantle the stove to replace the broken panel. In effect, there is a risk of losing the burner entirely if you go for caste iron.  On the other hand, steel burners do need to be made of sufficient thickness to avoid them failing after several years.

Some burners have back boilers or plate heaters that can be used to heat either hot water or radiators elsewhere in the house.  In some cases, you can buy a burner with this facility but you may not need to plumb in the water until a later date but this will depend on the design. But if your hose is well insulated in many cases burners may be unnecessary for heating and their value restricted to attracting guests to book.woodburner

When buying it is worth considering ease of cleaning out the ash and maintenance as well as ease or operation and control.  Looks are also a factor and many of the less expensive wood burners can come uncomfortably close to ugly.  In addition some prefer open fires as opposed to wood burners.  Some guests prefer an open fire and actively seek them.  They do require more attention to safety (for example spitting wood can prove a hazard) and are not so economic as wood burners.  In addition, assuming the fireplace is already available, installation can cost nothing beyond fettling an existing fire place and checking the chimney.  However, the innocent ignorance of guests is something that should always be guarded against.

One owner reported that guests finding the burner going strong, on departure for safety reasons, dowsed the burner with water cracking the grate and causing other damage.  It was a well intentioned act most likely caused by experience putting out camp fires but it caused significant damage.  Similar innocent well meaning acts could apply to open fire management.  With burners and open fires clear easy to read instructions and guidance should be provided.  Better to assume guests know nothing and appear to state the obvious than any danger or damage caused by well intentioned but wrong actions.

When enquiring about installation some may suggest quite high prices saying scaffolding will be needed.  In many cases if you seek out different quotations you will quickly find that some suppliers are quite keen to encourage you to pay more than might be necessary. Obviously, you should not encourage dangerous behaviour but it is useful to be aware that some are keen to see you spend more than might be necessary.

How large a stove is needed?  (1kw is the same as 3400 BTU)

Room size and the state of insulation of the house should be taken into account.  Normally you need 1kw from between 10m3 to 25m3 depending on the quality of the room and building.  To get the cubic volume of a room multiply the height but the width by the length.

It is important to ensure that an adequate flue either exists or can be installed.  Although it is possible to use an existing flue with a register plate to ensure that only the gas from the burner goes up it and there is no chance of leakage into the room, it is often a better plan to install  a chimney liner.  This reduces creosote build ups and the risk of chimney fires.  Sometimes the gap between the liner and the chimney flue walls is insulated to improve draw.

Some wood burners can be used to heat radiators and / or hot water.  A rule of thumb is that each radiator will need about 5,000 BTU, or about 1.5 kw and hot water will take around 9,000 BTU or about 2.65 kw.

When installing any burner it has to be approved by a HETAS engineer.  Normally it is a good idea to employ one who is qualified rather than depend on retrospective approval.

Operating Cottage Wood Burners

Fuel

woodburnerUse seasoned wood only.  Some types of wood season faster than others but a safe rule is to allow 18 months from felling to burning.   This will vary depending on the time of year the wood is felled.  If the sap is rising in spring a longer seasoning period is needed where if the felling is in early Winter there will be much less sap involved.

Store the wood outside, ideally off the ground and with a covering.  Do not use wet wood or any wood impregnated with glue.  Wax impregnated sawdust logs are normally intended for use on open fires and should not be used in wood burners but simple compressed wood / sawdust logs are okay.  The most effective wood to use is hardwood that tends to burn hotter producing less creosote with such woods as  Ash, Beech, Birch, Blackthorn, Eucalyptus, Alder, Apple, Pear Holly, Hawthorn, Hazel, Hornbeam, Maple, Oak, Rowan, Sycamore, Wild Cherry, Willow.  Soft wood like Pine or Poplar burns at a lower temperature and kicks out less heat.  With some experience, you will find that each type of wood has different burning characteristics.   Coal is often used with multi fuel burners but its quality can vary from poor which burns badly at a lowish temperature and creates a lot of clinker to high quality burn with little clinker.   Smokeless Coal is another alternative.  Bricquettes made of compressed wood are available and have the added factor of being easy to store coming flat often on pallets.  Multi-fuel burners provide a grate and a riddle so that coal can be used.  Coal prefers a draught from below where wood will burn happily without this.

Some owners avoid solid fuels and choose propane burners.  Insurance companies often prefer this option but the cost of bottled propane can be prohibitive depending on where you live.  But for well insulated holiday lets, where wood burners are more decorative or inessential extras less likely to see heavy use, propane firing could well an option worth pursuing.

Hardwood is preferable giving out an average of 1.8 times the heat of soft wood..  Some stoves in cold periods could consume as much as 4m3 per week.  High quality coal can produce four times the heat of hard wood.

Once you have bought and had your burner installed you will find that some will be easier to manage than others and this will be down to the burner, the flue, the type and quality of wood as well as the ability and knowledge of the user.

Some of the less expensive burners tend to blacken the glass quite easily. Cleaning this either involves using a shop bought spray which is not, always, that effective or you can choose, using gloves and goggles, a solution of about 500cc and a teaspoon full or concentration to suit of caustic soda crystals that can be bought at hardware stores.  Caustic soda, as the name implies, is caustic so using this chemical has to be done so with appropriate care.  By use of disposable white kitchen towel or similar, the black residue on the glass can be easily removed. It is absolutely essential to take the right safety measures if you choose this solution.  For moderate deposits a solution of vinegar, soap and a little water applied on paper can be quite effective if the more brutal, caustic approach is not preferred or necessary.

Meanwhile, providing all the necessary items to clean out and run the burner and ready it for lighting is essential.  Things such as fire brushes, a metal cinder bucket, wood basket, wood, fire lighters if required, kindling (you may have to use the expression ‘starting sticks’), clear operating and safety instructions and a handy store of wood.  Different burners will have differing methods of best lighting them and simple instructions are particularly important in this respect.  Among other things, the golden rule of keeping the door closed is essential along with what appears a common sense instruction not to try to dry a log perching it on top of the wood burner.

Controlling how much wood is burn can be difficult if the holiday let is managed from a distance.  However, if owners are locally based, some choose to provide a certain amount of wood free and then charge so much a basket for additional useage.  This formula tends not to be so welcome for cottages without other significant sources of heating.woodburner

The upside of wood burners is that they increase bookings in the shoulder and winter seasons, they can save on heating especially in rural areas where bottled gas is installed, and they can have some impact on rental levels in cooler periods of the year.  The downsides are that they do need managing, getting a good wood supplier can be hit or miss, they create more dirt and dust (this can vary depending on the quality, size and style of the burner, and installing one can easily exceed £2,000.

A note on wood:  Some wood needs more seasoning.  Ash will burn quite soon after cutting but could do with several months seasoning.  Sycamore burns well but can burn quite hot and quickly.  Oak needs seasoning and is a slow burn.  Poplar tends not to be so useful. Some wood spits and is only useful for burners: Cedar, Douglas Fir, Sweet and Horse Chestnut, Larch, Plane and Willow.    It is worth avoiding Elder, Lime, Pine, Poplar and Spruce.  Laburnum and Yew can be poisonous so should be kept away from any cooking area but Yew can give out significant heat for wood burner use.

General information

Type of wood Energy content (Kw per kg) % Water content (Newly cut) Years to season
The ideal moisture content to burn is 20% or lower but many burn at 25%.If cut when the sap is rising seasoning can take much longer
Ash 4.1 35 1
Beech 4.3 45 1-2
Birch 4.1 45 1
Oak 4.5 50 2-3
Poplar 2.6 65 1
Pine or Fir 2.6 60 1

Those pretty heat engine fans are not of great use, except for decoration, but more robust mainstream fans can be highly effective in distributing heat from wood burners.

Safety

woodburnerUse only newspaper to light the burner and keep a stock of dry kindling.  This makes starting fires easy and reliable and removes the need to clean out a failed attempt. The obvious precaution of keeping all inflammable items at a safe distance will apply and providing a handy fire extinguisher is a must.  Smoke alarms are key.  Sweeping out the flue on a regular basis is important and you should update any fire risk assessments you have to cover the wood burner.

Make sure you have the right kit.  This means a metal ash bucket, ideally with a cover and an outside spot on hard standing so that any of its contents can cool down before they are disposed of.  Ash can remain hot for a surprisingly long time because it is a good insulator and hot embers in the centre of a mass can remain so for many hours.  Do not use a domestic vacuum cleaner to clean up because the fine dust will very quickly clog its filters up and there is the outside danger of one tiny still hot ember finding its way into the bag and then further bad luck causing the vacuum cleaner to burst into flames.  This has happened.

An appropriately sized metal shovel for the burner is a must along with a fire brush and a purpose designed thermometer.  Some useful ones work on the bimetallic system.  Running a wood burner too hot will not only damage the stove but is not a safe thing to do, quite aside from the fact that it wastes fuel.  If you have a duel fuel burner or are tempted to mix coal with wood, avoid doing this.  The heat and temperature generated from a coal / wood mix can rise very fast and such mixed fuel burns are far more difficult to control.  The heat can damage the fire brick, the grate and much more so avoid mixing fossil fuels with wood.

If coal is to be used many duel fuel burners have instructions involving the grates and other aspects of operation from wood burning arrangements.  This should be kept in mind if you have a duel fuel burner before burning coal.

Every so often check the rope seals and latch on the door as well as the chimney cap.  Guard against corrosion if not in use for a prolonged period by leaving the door slightly open for airflow.  Finally, it is essential, along with the regulation ventilation, to have a Carbon Monoxide detector fitted.  Normal smoke detectors are insufficient.

TROUBLESHOOTING

1. Dirty or black marks on the glass:

• Damp wood. You should use 20% moisture or less if possible.

• Too little air from the top air intake.

• The fire is not hot enough

2. Smoke comes out when the door is opened:

• Check any damper is open and there are no obstructions in the flue.

• Avoid opening the door if there are high flames.

• The chimney might need sweeping. Adverse weather conditions and momentarily effect the draw.

3. Uncontrollable burning:woodburner

• Door seal damaged or broken.

• The chimney may be drawing too well (consider a draft regulator)

4. Smoke and difficulty lighting a fire:

• Poor seals on flue pipes and chimney

• Flue too short

5. Room cannot be heated effectively:

• Larger higher output stove needed

• Poor fuel

• Too much ash in grate

• Too little air for burning

6. Stove puts out too much heat:

• Too much air

• Too strong a draw from chimney (consider draught regulator)

7. Damaged grate:

• Too much fuel put in stove

• Wrong type of fuel

• Over supply of air

• chimney draws too much

Thanks to extra contributions from: new timber holidaycottages   kilmalkedachez la chouette  and  Greenbarn Cottages