Hex Energy Ltd replaced the Ground Source Heat Pump Systems (GSHP) at a group of schools.
The sites existing package plant rooms with 7No. Water Furnace EWK130 ground source heat pumps were at the end of their operational and maintenance lifecycles, so they have been decommissioned, removed, and replaced with alternative Mastertherm ground source heat pumps. Hex acted as principle Contractor for the full replacement works.
The existing boilers which are to be used as a top up / back up for the GSHP systems have been retained in the final re-fitted plantroom.
The existing air-cooled chiller has also remained, which is to be used as a top up / back up for the GSHP system.
New pipe work within the plant room between heat pumps and ground array and the buffer tanks including support and insulation has been installed.
We have installed new controls to deliver heating and cooling to the buffer tanks as and when required and using the outdoor ambient temperature to determine flow temperatures and optimise the heat pump system.
Key Plant Installed
Heat Pumps:
10 x Mastertherm AQ90I inverter driven reversible heat pumps
Buffer Vessel:
LTHW – 1000l Carbon steel buffer store Max. working pressure 6 bar insulation 100mm
CHW – 1000l Carbon steel buffer store Max. working pressure 6 bar vapour seal insulation 20mm thick PEXL
Boiler Shunt Pump:
1 x Grundfos TPD 65-170/4 A-F-A-BQQE-JX3 single-stage, close-coupled, volute twin head pump
2 x CUE 3×380-500V IP55 3,0KW frequency inverter
Control Strategy
The principal of operation is that the GSHP’s will use the MasterLan function to control the 3 port valves on each heat pump unit. The heat pump system will constantly monitor the buffer tank temperatures and when outside of set point (based on hysteresis) will enable and run the heat pump system to recovery the heating and cooling buffers. The heat pumps have been commissioned to work on weather compensation with the set point of the heat point automatically adjusting based on the outside temperature.
The new heat pumps will take over control of the boiler and chiller system so that the GSHP system operates to its maximum available capacity in heating and / or cooling mode and when the GSHP system cannot service the load, the GSHP control system will enable the boiler or chiller via the TRANE control system.
