Are biomass boilers efficient?

Biomass boilers can be efficient, but performance depends on more than the boiler's make or type. Correct sizing matters, as does fuel quality. Wet or unsuitable wood can reduce combustion efficiency. Controls and maintenance also influence how well the system performs over time. Running costs also depend on your circumstances. The heat you need, the fuel you choose, how much you can store, and what local suppliers charge will all affect running costs.

Can a biomass boiler run entirely automatically?

Some systems can automate much of the process, but they aren’t maintenance-free. Pellet and wood-chip boilers can automatically feed fuel into the combustion chamber and control the burning process. Some models also automate cleaning and ash removal within the boiler. You’ll still need to monitor the system, arrange fuel deliveries, empty the ash container when required, and ensure cleaning and servicing take place. As we’ve seen, log boilers require substantially more manual involvement because you have to load the fuel yourself.

Do I need planning permission to install one?

It depends on your property and the installation. In England, installing or replacing a boiler or heating system internally doesn’t normally require planning permission. An external flue may also fall within permitted development rights if it meets the relevant conditions. That said, you may need permission in some circumstances. This is particularly likely if your property is listed or in a designated area. A separate building or structure for storing fuel may have its own planning requirements. Remember that Building Regulations can apply even if planning permission isn’t needed. Check with your local planning authority before going ahead with any installation. Planning rules differ elsewhere in the UK.

A complete guide to wood-fuelled heating and biomass boilers

If you’re looking for an alternative to oil or gas heating on your farm or commercial premises, a biomass boiler could be worth considering.

Rather than burning fossil fuels, biomass boilers use organic material, most commonly wood pellets, chips, or logs. They can supply heating and hot water much like a conventional boiler, but differ in how they’re fuelled, operated, and maintained.

Biomass boilers can be particularly attractive if you have plenty of space to store fuel or access to a reliable local wood supply. It’s one of several technologies covered in our guide to renewable energy on farms.

Before investing, consider more than the cost of purchasing the boiler itself. Fuel costs, storage, efficiency, and emissions all affect whether a biomass boiler is right for your property. The Energy Saving Trust’s biomass guide provides useful independent information on these practical and environmental considerations.

A biomass system can also be a significant investment in machinery. If you’re considering installing one, you’ll need to think about maintenance, fire prevention, and appropriate biomass boiler insurance before you make your purchase.

What is a biomass boiler and what does it burn?

A biomass boiler is a solid-fuel heating system. It burns organic material to heat water, which can then circulate through radiators, underfloor heating or other heating systems. Systems can also provide hot water.

For most farm and commercial installations, the fuel used will be wood in one of three forms.

Wood pellets. These are made from compressed sawdust and other wood residues. Their consistent size makes them well suited to automated systems, where fuel is transferred from a storage hopper or silo into the boiler as required.

Wood chips. These are pieces of chipped timber. They’re often used for larger agricultural or commercial systems where there’s enough room for bulk storage and fuel-handling equipment.

Logs. Some biomass boiler systems can also burn logs. These systems require more manual input because you need to load the fuel yourself. Log boilers are often paired with a thermal store, which holds heated water until it’s needed.

Whichever fuel you use, its quality matters. Excess moisture or unsuitable fuel can reduce combustion efficiency and increase deposits inside the boiler.

Wood can be a renewable energy source when it comes from sustainably managed sources, but that doesn’t mean biomass heating is emission-free. Burning it releases carbon dioxide, particulate matter, and other pollutants. Fuel quality, appliance efficiency, and how you operate it can all affect emissions.

If you run a larger agricultural operation, your biomass system may be situated alongside buildings, machinery, vehicles, and other valuable assets. In this case, you should consider insurance for this under your farm insurance policy.

How a biomass heating system operates

The basic principle behind a biomass system is straightforward. Your boiler burns fuel to heat water, which is then circulated around your property.

1. Fuel storage and feeding

Before the fuel reaches your boiler, it needs a dry, suitable place to be stored.

Pellet and wood-chip systems often use a hopper or larger fuel store. From there, an automated feed system transfers the fuel into the combustion chamber. One common method uses an auger, essentially a powered screw that moves the fuel along a tube. 

Log boilers work differently. Instead of relying on an automatic feed system, you usually have to load the fuel directly into the boiler.

The size of your fuel store will depend on your specific system and how much heat you need to generate. A larger fuel reserve means fewer deliveries but takes up more space. You’ll also need to ensure you have adequate access, especially if fuel is delivered in bulk.

2. Ignition and combustion

Once the fuel reaches the combustion chamber, it’s ignited and burned.

Many pellet and wood-chip boilers control this automatically. Sensors and electronic controls regulate the fuel supply and airflow so that the boiler can respond to demand.

Good combustion depends partly on using the right fuel. If you use damp or poor-quality wood, it burns less effectively, leaves extra deposits in the system, and increases emissions.

3. Heat exchange

The heat produced by combustion is transferred to water through a heat exchanger. That heated water then circulates through your heating system. Depending on your installation, it might supply radiators, underfloor heating, hot-water cylinders, or heating for agricultural and commercial buildings.

Some systems also have a thermal store. This holds heated water for later use and can be particularly useful if you have a manually loaded log boiler.

4. Emission and exhaust

Gases generated during combustion in a biomass boiler need to leave the building safely through a suitable flue or chimney.

A correctly designed flue will carry combustion gases outside and help the boiler operate effectively. Because all wood-burning systems produce some air pollution, your choice of appliance, fuel, and maintenance regime can also affect the level of emissions.

There may be additional requirements if your property is in a smoke control area, so check what applies locally before choosing your system.

5. Ash collection

Burning wood leaves ash behind, so you need to deal with it as part of running the boiler. Many modern systems move ash automatically into a collection container. You still need to empty it periodically, and the frequency will depend on the boiler, fuel, and how heavily the system is being used.

Always follow the manufacturer’s instructions when removing and disposing of ash.

Day-to-day maintenance and what running a biomass boiler entails

One of the biggest practical differences between biomass and gas or oil heating is that they require more active intervention to keep the system running.

An automated pellet or wood-chip boiler can handle much of the feeding and combustion, but it isn’t completely hands-off. You still need to monitor fuel stocks, schedule deliveries before you run low, and keep stored fuel dry.

How much attention your boiler needs will vary. During a cold spell, for example, you may need to check the store and ash container more often as you use more fuel. A log boiler involves considerably more day-to-day work because you have to load the fuel yourself.

Fuel deliveries also need planning. If you buy pellets or chips in large quantities, your supplier needs suitable access to the store. You also need enough storage capacity to make deliveries practical and be able to protect the fuel from accumulating too much moisture.

You also have to deal with ash.  Even if your boiler automatically removes it from the combustion chamber, the collection container still needs emptying. Some boilers have self-cleaning functions, while others require manual removal of deposits from components such as the combustion grate or heat exchanger.

Alongside these routine jobs, you should arrange professional maintenance in line with the manufacturer’s instructions and any requirements of your insurance policy.

HETAS operates a scheme for businesses which identifies engineers competent to maintain domestic and commercial biomass appliances. You can use its biomass maintenance search to find a suitable provider.

It’s also sensible to keep a record of servicing and maintenance carried out on the system.

Insurance and risk management to protect your system

Biomass installations are high-value mechanical assets. They also involve considerably more mechanical equipment than a conventional gas boiler.

Depending on its design, your system might include an auger, motors, pumps, fans, sensors, and an electronic control panel, as well as the boiler and heat exchanger. A sudden failure of the feed auger, control panel, or heat exchanger could leave you without heat and with a significant repair bill.

The combination of solid fuel, combustion, and mechanical equipment also creates a different risk profile. Fire prevention should form part of how you manage the system. Ensure you follow the manufacturer’s instructions for storing fuel and maintaining the boiler. Keep boiler rooms and access areas tidy and deal promptly with faults or unusual behaviour from the system. Your fire detection and protection measures should be appropriate for the equipment and the premises where it’s installed.

You should also think about what a breakdown would mean for your business. If the boiler heats livestock buildings, workshops, offices, holiday accommodation, or other commercial premises, losing heat could cause disruption in addition to the cost of fixing the equipment itself.

It’s important not to assume that your system is fully covered under your standard building insurance. You’ll likely need specialist biomass boiler insurance to protect your investment. If your system is part of a farm, it can often be covered under your farm insurance policy.

If you’re considering installing a new system, it’s important to involve your broker or insurer at the planning stage. Your future insurance policy will have strict safety requirements, which can be costly to correct retroactively. Involving your broker or insurer at the planning stage ensures these requirements are considered from the very beginning.

When arranging or reviewing cover, make sure your broker understands the boiler, associated machinery, and fuel-storage arrangements. You should also tell them about any significant changes to the system or how you use it during the policy year.

FAQs

Protect your biomass investment

A biomass boiler can provide an alternative heat source for a farm or commercial property, but it requires more thought and effort than simply switching on a conventional boiler.

Before installing a biomass boiler system, make sure you have considered the available space, fuel supply and day-to-day work involved. Once it’s running, good maintenance and appropriate risk management can help protect both the equipment and your business.

If you’re installing a biomass boiler or want to review cover for an existing system, Alan Boswell Group can help you. Contact our specialist team today to discuss your installation and the cover available.

Speak to us: 01603 218000

A complete guide to wood-fuelled heating and biomass boilers

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What is a biomass boiler and what does it burn?