SLX 45 Wood Burning Stove: What It Is and How to Use One Safely

The Charnwood SLX 45 is a wood and anthracite stove with a built-in boiler, made by Charnwood and discontinued from 31 December 2021 as part of the 2022 Ecodesign regulation. That date matters to a household: you cannot buy one new, but if one is already fitted in your home you can keep using it, and in a power cut it can heat a room and run radiators without any electricity at all.

For a household preparing for outages, that is the point of it. The maker's datasheet gives a rated output to the room of 6.0kW on wood (range 4 to 7kW) and 4.6kW on anthracite, and to water 6.3kW on wood (range 4 to 7kW) and 9.7kW on anthracite¹. The maker describes the integral boiler as thermostatically controlled, with a heat output sufficient to power 8 to 9 radiators and ample hot water¹. The maker's product page gives different figures for the same model, and those are set out below.

What follows is what the stove does for a household in an emergency, how to run it safely, how to keep an existing one in working order, and where to go for parts and advice. It is not a buying guide: the model is no longer sold new.

What the SLX 45 is, and why it was discontinued

The SLX 45 is a solid fuel stove that burns wood or anthracite and carries an integral boiler, so the same fire that warms the room also heats water for radiators. The maker says it is also suitable for underfloor heating¹. The maker also states that the SLX 45 has identical looks and features to that of the SLX20¹, which tells you it belongs to a family of stoves rather than being a one-off design.

It was discontinued from 31 December 2021 as part of the new 2022 Ecodesign regulation. That regulation is the reason a new one is not on sale. Since January 2022, new stoves entering the UK market must be Ecodesign compliant², and official guidance is clear that any new stove placed on the market in the UK must now be Ecodesign compliant³. Ecodesign stoves produce lower emissions and are more efficient than non-Ecodesign stoves and open fires².

None of that makes an installed SLX 45 illegal or unsafe. The rules govern what is sold as new. What they do mean is that the model is a fixed point in time: parts and support come from the maker and the trade rather than from a current product line, and any replacement you consider will be a different, Ecodesign-compliant design.

The specifications below are the ones that decide how the stove is installed and what it can do. Where the maker's datasheet and the maker's product page disagree, both figures are given.

The maker's product page lists different output figures for the same model: 6.0kW to the room with a range of 2 to 7kW, 4.6kW to the room with a range of 2 to 5kW, and 6.3kW or 9.7kW to water. If the exact output matters to your installation, ask the maker or your installer which applies to your unit.

Fuel: wood or anthracite, and what not to burn

The SLX 45 burns wood or anthracite, and the fuel you choose changes both the output and the smoke. Official guidance recommends fuels from Defra's certified list of manufactured solid fuels, or dry untreated wood, for less smoke and better heat efficiency⁴. Anthracite is one of the smokeless coals: official guidance suggests considering anthracite, semi anthracite and low volatile steam coal, which produce less harmful particulates and can be used in smoke control areas².

There is a practical warning attached to fuel choice. Fire and rescue guidance is to use the right type of fuel, because using coal in wood stoves can damage them⁵. The SLX 45 is a multi-fuel design that the maker rates for anthracite, so the point is to burn what the maker specifies rather than whatever is to hand.

Burning the wrong material is a safety matter, not just a performance one. Fire and rescue services advise always ensuring you burn the correct fuel in open fires and wood burning stoves, because burning other materials can cause toxic fumes and increase the risk of chimney fires and carbon monoxide poisoning⁶. If you are unsure what you may burn where you live, the rules on smoke control areas set out what is permitted, and what wood and rubbish you should never burn covers the materials to keep out of the fire.

In a smoke control area, you can only burn unauthorised fuels such as wood on Defra exempt appliances, and you can only burn unauthorised fuels in Ecodesign stoves if they also appear on the list of Defra exempt appliances³. Check the status of your appliance and your area before you rely on wood as your main winter fuel.

• Wood: dry, untreated, and from a certified source where possible⁴.
• Anthracite and other smokeless coals: lower particulates, permitted in smoke control areas².
• Never: rubbish, treated wood or anything not intended for the appliance, because of toxic fumes, chimney fire and carbon monoxide risk⁶.

How dry the wood is affects how the stove burns and how much smoke it makes. The guidance on firewood explains what to look for and how to season logs.

Using the stove during a power cut

A stove with no electric controls is one of the few heating appliances that keeps working when the mains supply fails. That is its value to a household plan: it heats the room and, through the boiler, the radiators and hot water, with no pump-driven gas boiler and no fan.

The rest of the house still needs attention. Official advice during a power cut is to turn off items such as irons, ovens, electric fires and fryers, and to unplug your TV and computer, which can be damaged by a surge when power returns⁷. The same advice appears in the campaign guidance for power cuts⁸. Do that early, while you still have light to see by.

Light is the other thing to sort before dark. Keep a torch handy⁹, and keep a supply of candles as part of your preparations¹⁰. Candles carry a fire risk of their own, so the guidance on emergency lighting is worth reading before you depend on them. If you are cooking as well as heating, official food safety guidance notes that you can cook food and heat water using a camping stove, barbecue or bottled gas stove, checking the manufacturer's instructions for safe use¹¹. Those appliances are for outdoors: see the safety section below.

A simple order of work for the first hour of an outage:

1. Turn off irons, ovens, electric fires and fryers, and unplug the TV and computer⁷.
2. Check the stove is drawing properly and the room is ventilated before you add fuel¹².
3. Set out torches and candles where they will not be knocked over⁹.
4. Decide whether the boiler can run: if the system depends on a pump, do not run the stove hard on the boiler until you know how your system behaves. Ask your installer how your installation is arranged.
5. Keep the stove door closed and the fire guarded, and check the room again before you sleep.

Safe use and carbon monoxide

A stove is a controlled fire in the middle of your home, and the risks are smoke, chimney fire and carbon monoxide. The official advice is consistent across the fire and rescue services and the health bodies, and it is worth knowing in full.

Ventilation comes first. If you have a wood burner or other non-electric stove, make sure the room is well ventilated and follow all instructions carefully to avoid carbon monoxide poisoning¹². Make sure the ventilation system of your wood stove is clean and has no blockages, to prevent carbon monoxide build-up⁴. Welsh fire and rescue guidance makes the same point: ensure plenty of air comes into the room at all times and the chimney is clean, which helps burning and reduces airborne particles in the room, which are dangerous to health, especially for people with existing respiratory illness¹³.

Carbon monoxide is the danger that catches households out, because it has no smell. NHS Wales advice is to get heating and cooking appliances properly installed and keep them well maintained¹⁴. The Health and Safety Executive's position is that carbon monoxide can kill, and that safer alternatives such as electrical tools should be used where you can¹⁵.

The same rule applies to any fuel-burning device used outdoors: when using fuel-burning devices outdoors, the exhaust should not vent into enclosed shelters¹⁹. If you are relying on a stove for heat, keep the carbon monoxide risk in view all winter, not just on the first cold night. The guidance on home emergencies covers what to do if you suspect carbon monoxide, and using a wood burner safely goes through the air controls, door and guards in detail.

Keeping an existing stove in working order

An SLX 45 that is already fitted will outlast most of the appliances around it if it is looked after. The official advice is to have wood-burning and multi-fuel stoves serviced annually²⁰, and to get your stove serviced once a year². Regular maintenance and servicing, for example annually, and operating in line with the manufacturer's guidance and burning only permitted fuels, is the standard the guidance sets³.

The routine checks are simple and can be done by the household:

• Clean out the ash².
• Check the firebricks for cracks².
• Clean the stove glass².
• Check the seal around the stove door².
• Clean the outside of the stove or open fire².
• Keep flues clean and well maintained²¹.

Always ensure you follow the operating and maintenance instructions provided with the appliance²². For the wider system, schedule regular maintenance for all fuel-burning appliances, including furnaces, water heaters, gas stoves, fireplaces and boilers²³. If you have a boiler stove, the boiler and feed mechanism should be cleaned and serviced by a competent person as specified by the manufacturer's instructions²⁴.

A stove that is not burning correctly is a warning sign, not a nuisance. If your wood burner is not burning correctly, contact the company or shop that sold it to you, or contact the British Solid Fuel Appliance Manufacturers' Association for advice⁷. If you are having installation work done, always seek advice from a professional and ensure you use a qualified installer²¹; more information on qualified woodburning stove installers can be found at HETAS²¹.

The before-winter checklist is a good place to record the annual service and the flue check, and the wood burner lighting and safety kit checklist lists what to keep beside the stove.

Support, parts and servicing

Because the SLX 45 is out of production, support comes from three places: the maker, the trade body and the installer.

The first call for any fault is the company or shop that sold you the stove, or the British Solid Fuel Appliance Manufacturers' Association for advice⁷. For installation and any work on the flue or the boiler connection, use a qualified installer, and HETAS holds information on qualified woodburning stove installers²¹. For the boiler side of the appliance, a competent person should carry out the cleaning and servicing to the manufacturer's instructions²⁴.

Keep a record of the model, the installation date and each annual service. If you sell the house, or if you need a part, that record is what a dealer or installer will ask for first. The maker's own datasheet is the reference for the clearances and outputs of your unit¹.

If you are weighing up whether a solid fuel stove belongs in your plan at all, the section on heating and cooking without mains power or gas sets out the alternatives, and wood burners and multi-fuel stoves in a power cut covers how they behave when the electricity fails. The comparison of a wood burner or multi-fuel stove explains the difference between the two types, which matters if you are choosing what to install rather than what to keep.