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How Do Biomass Heating Systems & Boilers Work

At Rubbish Please Junk Collection, we know how to remove waste professionally. We do house clearances, sweep stuff away from garages, offices, or garden rubbish. But can you use self-generated or bought biomass to power your boiler and heating? We get that question a lot.

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Biomass Boilers Explained

Just like a traditional gas boiler, a biomass boiler or fossil fuel boiler is designed to provide all residents of your home with hot water and space heating, making it a standard heating system. 

However, what sets them apart from their gas counterparts is the fact that they’re fuelled by wood chips, pellets, logs, and other biomass instead of your traditional oil or gas, transforming these materials for heat via specialised heat exchangers and combustion chambers. It can be fed manually, semi-auto, or fully automated. The energy you don’t use, you store in a buffer container called a thermal tank.

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Biomass boilers are more environmentally friendly, since replacing fossil fuels with wood chips helps keep climate change at bay in the long term. While the combustion produces carbon dioxide, it’s actually offset by the amount of the gas absorbed by the plants while they were growing.

Every year, there are millions of tonnes of wood deposited in the UK’s landfill. The fate of this wood culminates in either a wood burner or its use as the fuel of biomass boilers (if the wood is processed into pellets). Beyond providing boiling water and heat, the latter option would also reduce the pressure on the landfill.

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How Do Biomass Boilers Work?

The way a biomass boiler works is very similar to its conventional counterpart. It burns fuel to produce thermal energy inside the combustion chamber. We call this gasification. We also used this for water heating. 

Gas releases from the combustion of fuel at 600 C, a temperature which is higher than what we usually see, are results of a two-stage burn process. In the combustion chamber, 1,200 C can be achieved because of the re-burn of sub-product gases. The furnace passes these through the metal heat exchanger, which heats the water on the other side. 

Storing Thermal Energy

Most installations require some sort of system to store energy accumulated over time as you don’t or can’t use everything a biomass boiler produces in any given moment.

Basically, this is a large vessel that holds water (around 30 litres / kW in energy output) that serves as a heat source, storing boiling water and then circulating via central heating systems. 

Temperature sensors are installed in the thermal store of the biomass boiler so that it keeps pre-defined temperatures. In this application, the boiler will turn on automatically when the thermal store dips below a certain temperature, then turn off automatically after the thermal store reaches its maximum temperature.

Downstream Heating

The system uses a strong pump to distribute hot water throughout the property or building.

Each end-point, be it a device or an entire room sends heat requests to the central biomass burner “on-demand”. This happens via the classic “flow & return” system. Pipes can be installed both above and under flooring or ground level. 

When you connect multiple properties, you have what we call “district heating”.

Biomass Boiler Size

In terms of size, it’s considerably larger than a gas boiler because of various factors at play, among which is the use of wood pellet fuel that requires a bigger combustion chamber while gas boilers are smaller.

The team at EBC (Easy Boiler Company) says that the installation of an automatic hopper feeder also contributes to the size of a boiler system. This hopper needs extra room and serves as storage for an extensive amount of wood pellets that will be automatically put into the combustion chamber as needed. 

Wood Pellet Feeders Require Infrequent Refuel

Ideally, you will want to have additional fuel storage at your property to keep spare wood pellets, so that heat production in your home doesn’t stop in case there’s a fuel supply interruption in the biomass boiler. According to experts What Storage, it’s also better if the storage location is near the usual spot of fuel delivery, to reduce carry distance putting an easier system in place.

We can also operate many residential wood pellet boilers using wood chips and logs, giving you more fuel options to choose from. 

So if you see these fuel alternatives as being easier to get or more economical, you can cut the operational cost of your biomass boiler by using them.

With use, the biomass boiler will be increasingly filled with ashes. You need to clean it about once every four weeks. 

While wood ash is great for compost and fertilises soil because of Potash it stores. Some biomass boilers are self-cleaning which means simply emptying the ash bin when it becomes full.

While you can keep your biomass boiler running all year round, let the system rest in the summer. According to experts Heatable, a new boiler installation of biomass units can be compatible and work alongside solar heating and electric showers, allowing tech to work together when necessary.

Smaller Alternatives of Heating Systems

If you think that a biomass boiler is too large for your property, you can opt for a smaller standalone wood stove for an at-home heating system. 

Typically, it serves as a single-room heater, fuelled by wood pellets or logs. But you can connect it to a back boiler that uses the thermal energy released during the combustion to heat water and the whole property.

Having a well-designed vent is “a must” whether you use a biomass boiler or a standalone wood stove because you want to have more airflow to run the stove properly.

You can fit a flexible chimney liner to your existing chimney to achieve a fairly economical solution.

You Should Have a Carbon Monoxide Detector

The presence of a carbon monoxide detector in your home is very important when you burn any form of hydrocarbon resource – like biomass, natural gas or coal. Theoretically, if fuel is fully combusted, it releases carbon dioxide emissions, heat and water.

But you can’t burn all the fuel, and this is the truth. So it’s possible that the combustion also produces dangerous gases like carbon monoxide, which can be fatal if breathed. 

For this reason, you need to install a carbon monoxide detector so that you can safely use your biomass boiler.

Costs of Wood Pellet Boilers & The Renewable Heat Incentive (RHI)

The average cost of biomass fuel such as wood pellets and logs is cheaper than using oil or water boilers for your heating system.

There is also the Renewable Heat Incentive (RHI) aiming to encourage the installation of biomass systems which would easily cut down on costs and achieve fuel savings.

There is also the debate of wood pellets or logs and their cost-efficiency. 

Wood pellets are created from waste wood materials, are the most suitable fuel for biomass boilers, and are much more controllable than logs. Pellets are also much more widely available than logs available in bulk or bagged. 

The use of log boilers requires more work and would potentially need more space.

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Fuel Storage for Biomass Boilers 

The setup of storage is also something to take into consideration. 

Finding space to store the fuel depends on the types of fuel. Whether chip or pellet, a block built room from which the fuel feed system transports wood chip or pellet just a short distance from the boiler provides an efficient system. 

  • For non-domestic use, integrate large containers. 
  • For wood chips, square floor space is ideal, install a circular agitator. 
  • For wood pellets, a rectangular ‘V’-profile angled floor is more effective. 

You could also use large containers in a fuel store which would need to include the installation of plywood lining and sealed joints to prevent condensation, which would lead to moisture content.

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Conclusion

Biomass boilers run on biomass fuels that fit the bill as a renewable resource. The fuels do produce carbon dioxide when they’re burnt, but their amount is counterbalanced by the quantity of the gas absorbed by the trees while they were growing. 

Learn: Recycling: The Facts 

This results in a considerable reduction in the emissions of carbon dioxide. At least around 9.5 tonnes can be saved annually when a wood boiler substitutes the use of a coal combustion system or electric heater.

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