DGC Workshop GAHP 28. March 2014

Overview  Basis for our experience  Basic considerations before installation  Installation aspects  Service aspects  Summary

Basis for our experience

Basis  Installation and service on installations  3 specially trained service technicians and 2 trained sales engineers  Primary air source heat pumps – only one ground source

Basic considerations before installation

Basic considerations  Is the installation suited for reduced operational temperature?  Need for hot water production?  GAHP share of total installed output should be considered  Backup/peek output boiler needed?  Controlling the function of the GAHP versus backup boiler  The GAHP is not suited for just being sold as a “normal” gas boiler to the installer  The GAHP runs best at 100% load

Installation aspects

 Buffer tank in relevant size  Correct flow shall be ensured  If the GAHP shall produce domestic hot water, the size of the heat exchanger is important  Freezing will be avoided if electric power is on. Otherwise glycol can be considered.

Service aspects

 No service on the “black part” of the GAHP  Basic service like a normal boiler plus oil pump  Knowledge of the control system essential  Paved area (solid ground) around the GAHP and space to make the service  Weather conditions in Denmark (difficult/impossible to make service in a rain or snow)

Service aspects  Most found lessons learnt:  Short working periods (icing, defrosting problems, low efficiency)  Too high return temperature (the GAHP will shut down at 57 degrees return temperature)  The installed gas boilers will take over with lower overall efficiency (sometimes the customer does not recognize this since the gas boiler can deliver enough energy)

Summary

Summary  Reduced operational temperature essential  Buffer tank and flow should be correct  Control of back up boiler important  Service aspects should be considered in the practical installation of the GAHP.

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