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Pellet heating: everything about costs, advantages & disadvantages

Pellet heating is a very resource-saving way of heating. We'll show you how this type of heating works, what advantages and disadvantages it has and what costs you have to reckon with when buying and installing it.

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What is a pellet heating system?

You shouldn't confuse a pellet heating system with a pellet stove. Both have pellets pressed from sawdust and other wood residues as fuel, but pellet heating is intended as central heating. That is, it supplies heat to the whole house. In contrast, a pellet stove is usually only designed to supply heat to one room.

Exception: a pellet stove as a so-called water-bearing stove. Here, part of the energy gained through the furnace is used for additional heating of service and / or heating water.

Modern pellet heating systems are pretty comfortable. Both the filling of the boiler with the pellets and the control and regulation of the system are largely automatic. This has made pellet heating systems more and more popular in recent years.

Number of wood pellet firings in Germany

There are an estimated 525,000 boilers and stoves in Germany in 2020 that are fired with wood pellets. This means that the total number of systems has more than doubled since 2011. Pellet boilers with a nominal heat output of less than 50 kilowatts make up the largest share.

How does a pellet heating system work?

Pellet heating systems use the oldest method of heat generation: they burn wood. This is transported from a storage room or storage container into the pellet boiler. Ignition and combustion then start automatically in the combustion chamber. This is then monitored and controlled by various measuring sensors. This is done so efficiently that most pellet boilers achieve a boiler efficiency of over 90 percent.

The heat generated in this way heats an integrated heat exchanger. This in turn passes the energy on to the heating circuit. Under certain circumstances, a buffer storage tank is added to this system, which holds the generated energy, so to speak (more on this later). What remains is ashes that have to be disposed of.

Here is a brief overview of the most important components:

  • Combustion control: Temperature sensors and exhaust gas sensors determine the heat output and control the combustion process by regulating the fuel, primary and secondary air supply.
  • Automatic ignition: The automatic ignition device ignites the wood pellets and then switches off again. This always happens when more energy / heat is required via the control of the central heating system.
  • Combustion air fan: Pellet heating systems receive the air required for combustion via a fan.
  • Burnback protection: It prevents the flame from shooting back from the boiler into the feed system and into the pellet storage room. Various technical systems such as flaps and sluices, but also extinguishing water devices, are used here.

What do I have to consider when buying a pellet heating system?

Are you interested in buying a pellet heating system? Then you should clarify the following technology and comfort questions beforehand:

Heating power

Just like with any other system of heat generation, you first have to determine what power your pellet heating should have in order to heat your house sufficiently. The important thing is Nominal heat output. This means the boiler's thermal output in full load operation. The nominal heat output should be geared precisely to the heat demand. Because: Too much (unnecessary) service costs too much money, if too little the booth stays cold.

In addition to the number of people living in the household, the size of the building, the number of rooms and the energetic state are of course important. The following table gives you a first, rough overview:

But as I said, these are only guidelines. To determine your individual needs, we recommend that you ask either a heating fitter or an energy advisor.

Storage of the pellets

There are different ways to store the wood pellets.

  • The cheapest option is one Tissue tank. This is actually nothing more than a large fabric sack in a frame.
  • Alternatively, there are (underground) Cisterns.
  • Airtight Plastic or metal silos can be set up in the basement.
  • Or you just leave one storage room (for example the old room for the heating oil cabinet).

The Deutsche Pelletinstitut GmbH (depi) recommends: "For small and medium-sized pellet heating systems (up to approx. 75 kW boiler output) the pellet store should be designed so that it can hold a complete annual demand for pellets usually use low summer prices ".

So if you do not want to have repeated deliveries, the pellet store must be dimensioned accordingly. With a pellet requirement of 3,750 kilograms per year (corresponds approximately to a heat requirement of 15,000 kWh), the depi calculates, you need a tank with a volume of around 6.5 cubic meters.

Attention: As a rule, wood pellets are delivered by a tanker. He blows the pellets into your warehouse via a hose. The distance between the tank and the truck parking space must not exceed 30 meters. Otherwise the blowing in will not work. You should also keep this in mind when planning the pellet store.

Also important: you must always store the pellets in a dry place. Damp or even mushy pellets clog the heating.

Quality of the pellets

Wood pellets are divided into three quality classes by standard: A1, A2 and B. You should only use A1 goods for your private pellet heating.

Further quality criteria are the "DINplus" mark from TÜV Rheinland, the FSC seal (Forest Stewardship Council) or the "DIN-Geprüft according to ISO 38200" mark. The pellets with the ENplus certificate are also considered high-quality pellets.

Conveyor technology for the pellets

The so-called discharge system is used to transport the pellets from the store to the boiler. There are two techniques for doing this.

  • On the one hand there is this Auger. This is no different than a large, twisted drill. As it rotates, it transports the pellets into the boiler. Option number two is the vacuum suction device. Important: When using a screw conveyor, the storage container or storage room must be connected directly to the pellet heating system or the boiler room.
  • The second option are Vacuum pumps. Here the pellets are sucked from the store into the boiler. This enables greater flexibility; the storage room and boiler room can be up to 25 meters apart.

You can find more information about pellet storage at the German Pellet Institute.

By the way: You can also operate a pellet heating system without a warehouse. Then you have to fill the kettle regularly by hand yourself.

Type of lighting

The pellets are not transported directly from the store into the combustion chamber. There is still an intermediate step. A distinction is again made between two different systems.

  • In the Thrust firing the pellets are pushed onto a grate from the side or into a steel plate from below. A sensor controls the filling level. The pellets are always in direct contact with the embers. If the heating switches off, the pellets continue to smolder. In order to use this residual heat, these boilers are therefore usually combined with a buffer storage tank.
  • Alternatively there is that Fall level system. There the pellets fall through a chute onto the grate without coming into contact with the embers. Here, the level is not monitored via a sensor, but via the measured values ​​of the combustion control.

Buffer storage

Because the heat generation in a log boiler cannot simply be switched on and off, the heat is temporarily stored in a buffer storage tank.

In contrast, pellet heating systems have highly developed control and regulation systems. Since pellets can be dosed very well and the heating output can also be easily controlled, a buffer storage tank is not absolutely necessary here.

Nevertheless, the installation of a buffer memory is worth considering. It usually extends the life of the boiler and has a positive effect on fuel consumption and emissions.

Experts recommend a buffer storage volume of around 20 liters per kilowatt of nominal heat output for pellet boilers. And whenever a buffer storage tank comes into play, you should also think about installing a supporting solar thermal system.

What does a pellet heating cost?

Pellet heating is not cheap to buy. The prices for the boilers are - depending on the nominal heat conduction - between 5,000 euros and just under 20,000 euros. Then there is the assembly. And don't forget the cost of the pellet store and the conveyor system. For this you also have to calculate around 3,000 euros to 4,000 euros.

Here you will find a comprehensive market overview with 419 pellet boiler models from 34 manufacturers. Alternatively, you can also browse the product database of the specialist agency for renewable raw materials.

In addition to the pure investment costs, consumption costs are of course also important in the long term. And that's where it gets interesting ...

How much heating costs do I save with a pellet heating system?

In terms of energy costs, wood pellets are among the cheapest energy sources. This is shown by the following comparison.

To supply a household with an annual heating energy requirement of 20,000 kilowatt hours (kWh) you need:

  • 20,000 kWh of gas. Average cost: 5.82 cents per kilowatt hour.
  • 1 l of heating oil = calorific value of 10 kwH = 2,000 liters of heating oil. Average cost: 50 euros for 100 liters.
  • 1 kg of pellets = calorific value of 5 kwH = 4,000 kg of pellets. Average cost: 200 euros for 1 ton

This then results in the following Total heating costs per year with a consumption of 20,000 kilowatt hours:

Even with a comparatively low oil price and a very benevolent gas price, the raw material pellets are still cheaper. Another advantage of the pellets: the price fluctuations are nowhere near as great as with fossil fuels.

However, this is only a rough estimate. Heating costs always depend to a great extent on the heating behavior, the performance of the heating and the energetic insulation of the house. And there are also regionally significant price differences. In this respect, the pure energy costs are likely to be higher for most of them. However, this does not change the relative price advantage of the pellets.

Is there a subsidy for pellet heating?

Pellet heating systems are funded by the Federal Office of Economics and Export Control. You will receive a grant of 35 percent of the eligible costs if the pellet boiler has a nominal heat output of at least five kilowatts. If you replace an old oil heater at the same time, the subsidy increases to 45 percent.

In the case of new buildings, it is also necessary that it is either a boiler with condensing technology or the system has a secondary separation system for the flue gas particles.

Here you can find more detailed information on funding options for pellet heating.

Pellet heating: the advantages and disadvantages

From a purely ecological point of view, a pellet heating system is a fine thing. Because: Two kilograms of the pellets made from sawdust and wood shavings replace one liter of heating oil. These are the others advantages:

  • Good energy balance: in addition to avoiding fossil fuels, pellets score with a high energy content.
  • Good ecological balance: The combustion is CO2-neutral due to the renewable fuel wood.
  • Stable prices: While oil and gas are subject to large price fluctuations, pellets are very price-stable.

All of this not only sounds good, it is. But it also applies disadvantage to consider:

  • High investment costs: Pellet heating systems are quite expensive to purchase.
  • Plan space requirements: For the boiler and, above all, for storing the pellets, you need sufficient and above all well-protected space.
  • Dispose of ash residues: Even if the pellets burn almost completely, ash remains behind. You have to take these regularly.

Conclusion: for whom is it worth buying a pellet heating system?

Whether it is worth purchasing a pellet heating system for you is not just a math problem. Of course, you should compare investment and operating costs, subsidies and the (approximate) price development of your current energy source with pellet heating. The possible lower costs are only one advantage. The better ecological balance compared to fossil fuels can also be a purchase criterion.

Anyone who plans to renovate their house anyway will also think about alternatives when it comes to insulation and heating. Both go hand in hand, simply installing a new (pellet) heating system without thinking about insulation is pointless.

In the end, it boils down to having to work with a professional to make a comprehensive list of costs and benefits. Get a qualified energy advisor to do this. In what form it supports you and what it costs and does, you can read in this article: