Why Froling

We decided that the best biomass boiler available was made by Froling in Austria. Our company is based on a team of engineers, not accountants. When we started working with boilers in 2011 before RHI was released, we had pretty much the choice of biomass boiler manufacturers as other companies hadn’t yet tied manufacturers down to a “sales area”. With that in mind could choose what we felt was the best biomass boiler available on the market.
We looked in detail at Eta, Gilles, Dragon Heat, Glen Farrow, Windhagger, Herz, ***************, but concluded that the best biomass boiler was the Froling range.


The boiler’s lifetime is dictated initially by its design and choice of components and materials. Once installed the user and the choice of fuels burnt also has a significant impact; we work hard on commissioning to explain to users how they can get the best from their biomass boiler.

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  • Froling have been building biomass boilers since the 1960’s.
  • New manufacturers of boilers can’t hope to gain the knowledge of burning and effects on materials that a long standing manufacturer has.
  • Froling build their boilers more heavily than any other manufacturer we have seen. As an example, the augers are formed from 8mm steel, we have seen many others that use 4 or 6mm. They will work for a while, but can’t hope to break up chips or drag through awkward shapes.
  • The fire bricks are thicker in a Froling than in other boilers. This holds the heat in the burn chamber and means it is longer before they need replacement.
  • Froling manufacture the whole system themselves, including the burn chambers.
  • They use robotic welders for much of the work.
  • Every single boiler is pressure tested.
  • The power used by all the motors is monitored. If they go over current, the controller switches them off or reverses them. Many boilers don’t do this, the result is drive systems end up working harder than they should and this results in premature failures.
  • All parts of a Froling boiler are replaceable, including the burn chambers and heat exchangers. In the event of a failure, the boiler would not need to be removed from site and therefore the RHI scheme would not be affected.



Fuel Efficiency

The best biomass boilers use up to 30% less fuel to produce the same amount of heat than those of poorer design. The process of generating heat from wood is:

  • The wood is heated to evaporate and drive off moisture. This heat does not warm the boiler or burn chamber.
  • The wood starts to break down chemically at 260° C and volatile matter is vaporized. These vapours contain between 50 and 60 percent of the heat value of the wood.
  • At 600° CF these vapours burn. This high temperature must be maintained for maximum efficiency in combustion.
  • Following the release of volatile gases, the remaining material is charcoal, which burns at temperatures exceeding 600° C.

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The design of the Froling biomass boilers is all about getting the most out of each of the 4 steps above. As an example, the sloping grate of the TX boilers make the hot gases circulate through the wood as it enters the burn chamber. As the material dries it travels down the grate where more and more air is pumped underneath the fire grate to speed the volatalisation. Once produced the mixing chamber above the fire enables the highly flammable gasses to be thoroughly mixed with even more oxygen creating the maximum possible burn temperatures. The super thick fire bricks protect the steel of the burn chamber and allow more and more heat to be contained and generated inside the burn chamber. This coupled with a further forced blast of air allows the maximum temperatures from the charcoal phase to be generated. Boilers of lower quality rely on passive sucked air to attempt to produce these high temperatures. Thinner fire bricks mean that the steel boiler casings have to be water cooled which reduces the burn temperatures and therefore the efficiency of the heat production from the fuel.

All of the above is irrelevant if there is no means of controlling the fire. The Froling H3200 touch screen computer is constantly looking for the ability to run at maximum output and maximum efficiency. Fuel feed is controlled by residual oxygen content, flue gas temperature, boiler water temperature and burn chamber temperatures. Feed rate is constantly adjusted to maintain the boiler at its optimum output so that it never uses too much fuel.

Parts availability

Smaller boiler manufacturers can’t possibly hold the level of stock that Froling hold. They don’t have the troughput. Froling manufacture 30,000 boilers per year. The parts backup is first class. It is just “normal” to expect the parts to be in stock and for them to be despatched that day. If we order before 1pm UK time we can have them the next day.




When we first started, we had to guess at how reliable the Froling boiler would be. Now with hundreds of boilers installed we can speak with experience. The Froling boiler is the most reliable boiler on the market. We look after boilers of almost every make available for other customers, the Frolings are by far the least trouble. Even Pete Lord who runs a large wood chipping business supplying hundreds of different boilers says “fit a Froling everytime”. For fuel feed and cleaning, all the motors are sized slightly bigger than other manufacturers, centres of augers are heavier duty and power requirement monitoring is better.

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The software is written to look after the boiler, many boilers don’t measure negative pressure or the temperature in the burn chamber. Without this information, there is no control over the temperatures which can vary wildly with different fuels. Too high a temperature and the boiler will be damaged, too low and the fuel won’t be burnt properly.

Technical Support

Many manufacturers put their boiler in a box deliver it to site and let the installers get on with it. Froeling insist that the installing company is properly trained. They have a huge training centre at their factory in Grieskirchen, Austria. All the NerG lead engineers have been to this training facility. In addition, when there is a problem, we can actually get hold of their technical team. Where Froling really differ is that in Austria and Germany, they provide support direct to the end user. The result of this is that when we talk to our support team, they know exactly what we are talking about. They have been there, they’ve had their boilers to bits in front of customers and they have a driving attitude to “getting it fixed”.



Ease of maintenance

The Froling Boiler range are all designed to look after themselves. Many of the alternative boilers on the market will need daily maintainence to for example clear the ash from the burning grate. The Froling boilers have automated cleaning cycles built into the controller. The turbulators, which are used to increase the hot air’s contact with the heat exchanger, are shaken up and down. This cleans the surface of the heat exchanger tubes and also shakes off any ash dust which has settled in the tubes.

The fire grate self cleans on a controlled cycle ensuring that the fire can always burn at it’s optimum level. Finally the ash screw operates in order to clear the tiny amount of ash that is produced to the ash box. In addition the froeling Biomass boilers can monitor water pressures and temperatures and alert if issues are sensed.


Does a boiler need to notify you of an error? Biomass boilers are more complicated than oil or gas boilers. Their fuels are not completely homogenous and consistent. They are mechanical and things go wrong. Some of the most basic boilers have no means of telling you this. They just stop! The next step up is to have a light come on or an alarm sound or perhaps send a text message informing of an error. The Froeling boilers can be internet connected. This internet connection will notify you of any boiler errors, but will also tell you what that error is. Even better, you can access the boiler screen and take control from wherever you are. The same connection also allows the biomass boilers to be connected to BMS (Building Management Systems) which are used to control heating and ventilation in larger building systems. Of all the internet connected bilers we have seen the Froling system gives the greatest flexibility of control from anywhere on the internet. As installation and service partners, NerG can even access the logged data and advanced settings.



In summary we feel very proud and privileged to have the opportunity and trust to fit the Froeling range of boilers. The Austrian team are so passionate about their product and it really is a class above all the other boilers we have work on.