Ground Source Heat Pump (GSHP) systems have significant potential to reduce carbon emissions. The performance of GSHPs is highly dependent on their interaction with the ground and specifically the extraction and injection of the heat. A number of literature reviews has shown how the performance of GSHP systems vary in practice when compared to the theoretical aspects. This paper provides detailed investigative work on heat metering installation difficulties and associated errors which affect the long term practical performance of GSHP systems. Particularly, incorrect installation of heat meters is a sensitive issue for a heat metering scheme designed to evaluate the performance of any heating technology since it's likely that they will bias the readings. The findings obtained from this work confirm a range of generic installation problems that the refrigeration, air condition and heat pump (RACHP) industry is currently facing. The findings obtained from this study provide useful information for design and implementation of future GSHP systems in terms of improving energy efficiency as well as reducing costs. This study has identified a range of installation errors which include (i) temperature sensors being incorrectly positioned and/or installed (ii) incorrect selection of heat meters (iii) type of thermocouple pockets and (iv) poorly insulated sensors, all of which have contributed to an uncertainty error of +/- 25 % of the system performance.