Meynell Hall

Project Overview

Meynell Hall is a Grade 1 listed building and has been known by that name since 1547. Prior to this it was known as Broctune Abbey and before the dissolution of the monasteries Broctune Abbey was one of about five daughter abbeys of Rievaulx playing an essential role in its survival. The new owners have lovingly restored the buildings actually reverting much of it back to its original look and feel. Being listed means the fabric, features and existing fixtures must remain untouched. This includes keeping the single glazed windows, lathe and plaster walls, lime plaster and mortar and 1 metre thick stone walls. It was a challenge in itself to apply insulation to the hall as planning constraints would not allow the walls to be touched and some of the floors could not be removed. The areas which could be improved included the kitchen and living room on the ground floor but only with under floor heating, and the loft room. The roof was stripped and retiled with original tiles and the roof was fully insulated. The loft room and family bathroom was installed with under floor heating in a biscuit screed to give thermal mass and to compensate for the large heat losses. All other rooms benefitted from cast iron radiators. The entire heating system was sized at a low 45°C flow temperature to help with the efficiency of the system.

After a lengthy discussion with the client HT Energy Limited were able to design a very specific system that could conquer the problems that came with a 800+ year old Medieval country hall, mainly that of cost, upheaval, controllability and reliability. In order to minimise this disruption whilst still providing an energy efficient, carbon reducing system an innovative ground source heat pump installation was specified for the property. Not only did HT Energy design the system but also gave advise and recommendations for the actual insulation used to reduce the heat loss of the building and how to implement it.

The biggest challenge was that the Ground Source Heat Pump system would need to be run on a single phase supply and as the heat loss was calculated at 22kw a system was designed by HT Energy to cover the load 100% in line with MCS requirements. The system would need to supply all of the hot water for the house and the three bathrooms.

The client was extremely conscious of the listings and authority requirements so the project was never going to be straight forward. The brief was to take care and attention of every aspect of the renovation including the implementing of the heating system. Contracts were signed in August 2012 and work was to start straight away with trenching for the field collector pipes.

The location of the components was a crucial aspect of the installation due to the nature of the building and the beautiful area it was located within. Opting for the ground source heat pump systems installed in parallel as one system provided a practical, reliable and controllable heating system that ensured that the system could be fully installed in accordance with the planning authorities’ requirements, with full consideration to the location and history of the building. The system was fully installed in accordance with authorities planning requirements, to suit the building and surrounding facades. A plant room was formed in an outbuilding adjacent to the hall and highly insulated service pipes were used to link the plant room to the house. This meant there were no tanks or boilers in the living space of the hall.

As part of the original proposal process, a full elemental heat loss calculation was performed to be able to size the heat pump and to ascertain the correct heat emitter for each space and room in the hall. It also allowed for detailed discussions with the client and authorities to see if any further insulation could be practically applied or indeed allowed which would help with lowering the heat loss.

The 40mm PEM pipe was laid in sand at a depth of 1.2m, the 4 x 400m loops were connected to a 4 port manifold chamber and 2 x header pipes were taken to the plant room. The trenches were back filled after a full test.

Building work continued slowly with major works to rebuild the complete corner of the hall. At this stage and due to the fact that it was an external plant room, we installed the heat pump plant including 2 x 12kw single phase NIBE 1145 units, 500Lt hot water storage tank and 500Lt heating buffer. All circ pumps used were Grundfos Magna A rated pumps.

The system could be run up for the first time before Christmas 2012 ready to be applied to the hall when access was available to start indoor works.

The Under floor heating distribution was installed beginning of January to the kitchen and lounge areas plus the loft and bath rooms. After screeding works were complete, the heating was set to a floor drying program in the heat pump master unit. The next phase was to install the heating distribution in the form of UFH and some cast radiators. The entire system was designed to run at 40 DegC MWT. This work was completed in January 2013. Once the flooring was reinstated other building work could be done.