Innovative control expansion from Viessmann controls local heating network

Three residential and company buildings are centrally supplied with heat from a pellet boiler

Jakob Heizung & Sanitär GmbH is a specialist company with tradition. The family business, which is based in the North Hessian half-timbered town of Naumburg, celebrates its 125th anniversary this year and is now managed in the fourth and fifth generations by the state guild master Jürgen Jakob and his son Chief foreman Thorsten Jakob.

Since it was founded in 1892, the family business has been involved in almost every technical development in the industry: from the early wood, coal and oil stoves to the first central heating systems in the 1950s and today's widely used condensing boilers, heat pumps and modern pellet boilers. The range of services also includes bathrooms and drinking water installations as well as ventilation and air conditioning systems.

Modernisation of heating systems in own operation

Even a heating specialist needs a new heating system at some point. "Years ago, we decided to use wood as an energy source for the existing system that supplies our 250 square metre company building and the two neighbouring private houses of our families," reports Thorsten Jakob, master plumber and heating engineer. Wood is a domestic raw material that does not have to be imported from other countries. It is always available regardless of the weather, the time of day or the season and can easily be stored. The Jakobs also attached particular importance to burning wood in a CO2-neutral and therefore climate-friendly way. For these reasons, the new heat generator should also be a biomass boiler.

"For comfort," says Thorsten Jakob, "wood pellets were the first choice." Modern pellet boilers allow fully automatic plant operation. The decision was made in favour of the Vitoligno 300-C pellet boiler with a rated heat output of 40 kilowatts, as Jürgen and Thorsten Jakob had already installed boilers of this type at their customers on a number of occasions and had thus made many positive experiences. With its numerous automatic functions, the boiler can be operated independently and with minimum effort, similar to an oil or gas boiler. In addition to fuel supply, the automatic functions include power-saving ignition and cyclic ash removal from the heat exchanger and grate. In addition, this boiler with efficiencies of up to 95.1 percent is particularly economical with the fuel.

New pellet boiler provides most of the annual heating work

"Today, around 650 square metres of residential, office and storage space are mainly supplied by the new pellet boiler," explains Thorsten Jakob. On particularly cold days, a log boiler can still be used for heating. Solar systems on the two houses, each with two vacuum tube collectors, support the heating system.

The heat generated in the central heating system in the company building reaches the other two buildings via a local heating network with a total length of around 60 metres. Heating water buffer tanks in each building supply two heating circuits and also supply the hot water required for showering, washing and cooking, as well as absorbing the solar heat from the vacuum tube collectors. The entire system is centrally controlled by the innovative Vitotrol 350-C control extension, in the further development of which Thorsten Jakob played a major role.

Actively involved in the development of control systems

With its wide range of functions, this boiler control extension is unique. It can be used as remote control and cascade control for up to four biomass boilers as well as for complete monitoring and control of a local heating network.

Especially the control of his local heating network was important for Thorsten Jakob. He therefore actively participated in the further development of the Vitotrol 350-C, exchanged practical experience with the developers and took part in several workshops run by Viessmann Holzheiztechnik GmbH in Wolfurt, Austria. At Jakobs, the extended control system monitors, among other things, the state of charge of the three buffer storage tanks and optimises the operation of the pellet boiler. In order to avoid, for example, the pellet boiler having to start up separately just to supply a single buffer storage tank with heat, this storage tank is forcibly heated when the boiler is in operation anyway - even when it is still half full.

With the Vitotrol 350-C as remote control, the boiler can also be operated conveniently from the living room. All important information is shown on the five-inch colour touch display and all relevant parameters can be set via it. In addition, controller modules can be used to extend the system to up to 20 control loops. They are connected via CAN bus and freely configured, for example as heating circuits, DHW heating, long-distance heat pipes or heating water buffer tanks. This allows a versatile use and the implementation of complex as well as extensive control scenarios.

Heating and DHW heating costs halved

The new heating system was commissioned in the summer of 2015. Since then, the combination of a modern pellet boiler in the local heating network and solar collectors to support the heating of residential buildings has proven to be efficient and reliable. "Compared to a classic oil heating system, our solution has halved the costs for heating and hot water preparation," says Thorsten Jakob.

Additional information:

With pellet boilers, the strict EnEV specifications can be easily fulfilled

Modern wood pellet boilers are equally suitable for existing and new buildings. In new buildings, they offer the advantage that the stricter requirements of the Energy Saving Ordinance (EnEV), which came into force on 1 January 2016, can be met cost-effectively. In contrast, the 25 percent reduction in the permissible primary energy requirement in new buildings since this date cannot generally be achieved economically with additional thermal insulation measures. The use of a pellet boiler requires significantly lower investments.

May 2017