Mesophilic digestion mode is performed at 37-40°С. In order to secure live activity of microorganisms it constant temperature support with this rang is required. For that purpose biogas plant is equipped with digesters heating system. Depending on biogas plant option heat power is supplied by co-generator or by burning biogas in a boiler. Boilers are usually installed in technical building. Digester heating system is installed inside the concrete bottom and mounted on digester wall. Heating system consists of circulation pumps, temperature regulators, check valves, temperature and pressure sensors, stop valves, membrane tank for water heat extension compensation. System feeding is done from separate tank with polypropylene glycol solution. Heating mains are laid in earth trench and made of polyethylene pipes with heat insulation and cover layers.