This standard is intended for use by operators@ manufacturers@ service contractors@ and designers of micro CHP systems up to 20 kWel or with a fuel input up to 70 kW on the basis of the following micro CHP prime movers: ? petrol engines ? diesel engines ? Stirling engines ? steam engines ? micro gas turbines ? fuel cells (PEMFC/SOFC) The necessary service work on the types of CHP system listed above is presented in the checklists in the Annex. The general@ technologically neutral service work is presented in the checklist in VDI 4682 Part 1. For integrated peak load devices and additional heaters@ the part 3 of the series of standards is also to be applied. For CHP systems with internal combustion engines and a greater fuel input than 70 kW@ VDI 4680 applies.