Cars that let you know when they need servicing. Washing machines that can be oper­ated by smart­phone. Fully auto­mated produc­tion processes in which work­pieces commu­ni­cate with one another. There is hardly any area of life and hardly any appli­ca­tion that have not yet been conquered by digi­ti­za­tion – and that includes the heating systems sector. For some years now, users have enjoyed the bene­fits of mobile internet control over their heating systems. But this still has plenty more poten­tial to offer. Although users and devices are already able to interact, there has until now been virtu­ally no digital commu­ni­ca­tion within the gas condensing boiler itself, in other words between combus­tion controller, control system, pumps, valves and blowers. The indi­vidual compo­nents are packed with intel­li­gence and constantly produce data, but the central combus­tion controller has not been able to make use of this. All that is about to change. The Local Inter­con­nect Network (LIN-Bus), a commu­ni­ca­tion solu­tion that has already been employed in the auto­mo­tive industry for many years, is now becoming estab­lished for condensing boilers as well. The LIN is stan­dard­ized in accor­dance with ISO 17987, thus guar­an­teeing commu­ni­ca­tion compat­i­bility with different compo­nents.

Figure 1: Gas condensing blowers VG 71 and VG 100 from the RadiMix product range. (Foto | ebm-papst)

The serial field bus system inter­con­nects sensors, actu­a­tors and their control devices in a network. For condensing boilers, this means: Pumps, valves, sensors and blowers are linked to the combus­tion controller. The LIN-Bus is a single-master/­multi-slave system. The combus­tion controller is the master in this case. On the basis of a defined schedule, it regu­larly requests data from the system compo­nents (the slaves), eval­u­ates the infor­ma­tion, and sends back commands (see box for an expla­na­tion of how this works). A prereq­ui­site is that the system compo­nents are LIN-capable. Engi­neers at ebm-papst already devel­oped a gas blower that satis­fied the tech­nical require­ments ten years ago. But no other LIN-capable compo­nents were avail­able for heating systems at that time, so that the concept was not able to gain a foothold. Since then, other manu­fac­turers of compo­nents such as pumps have however followed suit. And so, for the first time, boilers now exist that are able to make use of this well-estab­lished commu­ni­ca­tion system. The two ebm-papst VG 71 and VG 100 blowers (Fig. 1) for a heat output up to 50 kilo­watts from the RadiMix product range are LIN-capable. This power range makes them suit­able for use in indi­vidual houses and apart­ment blocks. Sizes VG 108 and VG 122 for up to 150 kW are set to follow in the future.

Figure 2: Example of a LIN message for a gas blower. (Foto | ebm-papst)

Lean commu­ni­ca­tion solu­tion

Boiler manu­fac­turers can now also make use of sensor data which up until now the blower was only able to process inter­nally but not transmit to the combus­tion controller. This includes infor­ma­tion on power consump­tion, speed and ambient temper­a­ture. A new feature is the analysis of voltage fluc­tu­a­tions, which permits eval­u­a­tion of the network quality. The soft­ware was programmed by ebm-papst to create defined data packets, so-called LIN messages (Fig. 2), that are called up by the combus­tion controller. This data, as well as addi­tional sensor values in future, will enable manu­fac­turers to further opti­mize combus­tion and thus make the boiler more effi­cient. Because the LIN-Bus is bidi­rec­tional. It does not merely serve the purpose of calling up data, it can also be used to transmit commands. So the option now exists of posi­tioning the speed controller directly in the blower. The speed can thus be regu­lated more quickly and more precisely, which in turn provides scope for extending the modu­la­tion range. What’s more, moving the control system to the blower relieves the load on the compu­ta­tional capacity of the combus­tion controller. Fig. 3 illus­trates LIN-Bus commu­ni­ca­tion in a gas boiler.

Figure 3: Block diagram of a gas condensing boiler composite system. The green lines show the flow of data with LIN commu­ni­ca­tion. (Foto | ebm-papst)

Simple main­te­nance

The ease of reading out data is also of great advan­tage for main­te­nance purposes. It has long since become stan­dard prac­tice for cars to auto­mat­i­cally indi­cate that the engine oil needs changing or to report brake wear. In the event of a fault, all the work­shop mechanic has to do is to connect up a laptop and read out the fault and diag­nostic data to be able to rectify the specific problem. The LIN-Bus makes this a real option for heating system fitters as well. They can then iden­tify the problem directly on the monitor and so avoid having to perform exten­sive trouble-shooting and random compo­nent replace­ment.

Taking action before the error occurs

The eval­u­a­tion of oper­ating hours, start-stop cycles and ambient temper­a­ture profiles permits simple status moni­toring with LIN blowers. In the future, predic­tive main­te­nance will also be possible thanks to LIN-Bus commu­ni­ca­tion. This is an extremely valu­able func­tion for end users, as it mini­mizes the risk of sudden failure and provides advance warning of immi­nent failure. Gas boilers will be able to report the need to exchange compo­nents – before the fault actu­ally occurs. The combus­tion controller then receives a LIN message indi­cating that main­te­nance and replace­ment are neces­sary. If the boiler is also linked up to the internet, the infor­ma­tion will be auto­mat­i­cally sent to the fitter, who can then read out the diag­nosis and bring the right replace­ment part straight away. Showers suddenly running cold will then be a thing of the past.

The LIN-Bus