In August 2016, Pure Renewables was asked to conduct a feasibility study with regards to installing a ground source heat pump system into a large country residence just outside Malton, N Yorkshire.
Whelham Hall sits on 10.5 acres of land and boasts a large spring-fed lake to the front of the property. Having conducted a heat loss calculation for the property, Pure Renewables designed an appropriately sized ground source heat pump of a maximum capacity of 30kW output to provide heating and hot water to the whole property.
A backup oil boiler was also incorporated into the system which is controlled by the heat pump if required (typically in very cold sub-zero temperatures).
The outlet temperature of the lake was regularly measured through the winter of 2016/17 and was found to drop to be no lower than seven degrees – in heat pump terms this is classified as ‘warm’! It was therefore decided that the lake should be used as the energy source for the heat pump by utilising two Energy Blades (large heat exchangers) to extract the water’s energy.
The Energy Blades provide an energy capacity of 15kW in a moderately-flowing river or lake, even at a water temperature of just 4 degrees. The Energy Blade is a stainless steel, water-immersible heat exchanger specifically intended for use in closed-loop ground-source heat pumps systems. It is used for transferring energy from rivers, streams, lakes or ponds to the heat transfer fluid (glycol, anti-freeze) used by ground source heat pumps.
Given the heat requirement, we installed two Energy Blades to provide the 30kW required. Given the relatively small size of the blades, we were able to position them at the mouth of the sluice weir of the lake, thus ensuring good flow across them at all times.
The installation was carried out through Q1 of 2017 with the heat pump going live in March 2017.
The property owner, Hon Simon Howard, had a very positive experience using water source heat pumps, so understood the value of renewable energy systems. He has monitored his new system closely and despite experiencing a colder than usual 2017/18 winter, the system has returned a real-life Seasonal Performance Coefficient of 3.36. In effect, this means that the system has been 336% efficient whereby for every Kw of electricity consumed, the system has delivered 3.36kW of useful heat to the property. Furthermore, Simon reported that the house was warm and comfortable throughout the winter months with plenty of hot water from a 500ltr cylinder for an average occupancy of four. The oil boiler consumed zero oil (i.e. it didn’t come on once during the winter).