Heat pump champs and chumps

Steve Pester, BRE, turns his attention to the findings of the latest heat pump trials conducted by the Energy Saving Trust (EST)  

At BRE we have been working with DECC and EST to install hundreds of monitoring kits on domestic heat pump systems as part of the RHPP trials. The monitoring is part of a drive by DECC to understand the factors affecting the seasonal performance of actual installed heat pump systems in the real world. This work has given some of us the chance to see a lot of heat pump installations in quick succession and in many different geographic locations, so I thought it might be useful to say a few words on the installation quality we are seeing.

What is clear is that there are many excellent heat pump installations out there where installers have taken pride in their work; system layouts are clear and neat and my money would be on these systems to be working as specified.

However, it is also clear that this situation is not universal – here are some of the typical bloopers we have noticed:

  • Circulation pumps running constantly
  • No drain provision for condensate – this can cause injury when a sheet of ice forms around the heat pump in winter
  • Filling loops left connected. This is sometimes associated with slow pressure loss – fix the leak!
  • Messy or unsupported wiring
  • Hot water cylinder sensors loose in pockets or not secured properly
  • Controls not set up properly (e.g. disinfection cycle not set up)
  • No simple written explanation for the householder on how to use the system – many are confused by the longer response times of heat pumps, what to do when they go away on holiday, etc.

Of course, subcontractors are often used for plumbing and wiring jobs and perhaps this is a contributing factor. However, the responsibility for installation quality remains with the certified installer – this is a fundamental part of the MCS scheme.