Pile geothermal exchangers are a popular new type of geothermal exchanger for use in ground source heat pump systems due to their technical and cost improvements over traditional borehole geothermal exchangers. An in-situ full-scale study using the thermal response and thermal performance tests (TRT and TPT) is performed to investigate the heat exchange capacity of the cement-fly ash-gravel (CFG) piles usually used in foundations for low to medium high-rise buildings in Beijing. This paper analyzes the influences of the hydration heat of cement, heating power, inlet water temperature, circulating water flow velocity, operation mode, and group-pile effects on the heat exchange capacity of CFG pile geothermal exchangers. The test results can be used for the thermal design of CFG energy piles. (C) 2014 Elsevier B.V. All rights reserved.