Agricultural Barn Conversion, Worcestershire

Preliminary items

Upon the customer awarding the contract to WRE, prior to commencing the installation a number of detailed design items were undertaken. These were:

Heat Loss Calculations – to confirm the size of ground and air source heat pumps specified based upon the actual U-values of the various building elements, internally heated areas and internal design temperatures.

Wind & Snow Load Calculations – to confirm the roof was structurally capable of supporting the loads to be imposed upon it by the PV system.

Probable Water Demand Calculation – to establish the flow rate required from the incoming cold water main to meet the property water demands.

Distribution Network Operator (DNO) applications – to obtain connection offers to connect the proposed ground source heat pump and PV system to the national grid.

Mechanical Ventilation & Heat Recovery (MVHR) Design – to ensure building regulation ventilation rates are achieved with balanced supply and extract rates.

Site survey

Prior to commencing installation work, a site survey was undertaken to go through the proposed works as set out in the formal design guide produced for the project following completion of the preliminary items design work.

The design guide, specific to the project, set out all the information associated  with the installation for reference by all parties involved, resulting in works progressing smoothly and an uncompromised end installation.

Ground loop excavation

All top soil was removed and piled away from the excavation area. Ten 100m long trenches were then excavated with a width and depth of 1m, each separated from one another by 5m to allow for sufficient thermal recovery of the ground. The 5m separation also enabled ease or working allowing plant access to drive up and down the length of the trenches and for all spoil to be piled in between them.

A 3m square by 1m deep pit was also excavated to accommodate the external geothermal manifold chamber, again allowing for ease of access and working.

Ground loop trench preparation & ground loop installation

Each trench was bedded with 100mm of sand prior to the installation of the ground loops, the sand serving to both protect the ground loop pipework from any sharps in the bottom of the trenches and also to ensure good thermal contact between the ground loop pipework and surrounding ground.

The ground loops were then installed.

Ground Loop electrofusion welding

With all the ground loops laid, the end of each pipe was then electrofusion welded to the appropriate connection of the geothermal manifold chamber.

This involved a strict procedure of pipe cutting, marking, scrapping, cleaning, clamping and welding to ensure dependable welds.

The end of each pipe was cut square and even using a special pipe cutter, and any burrs or shaving were removed as failure to do so can leave the heating wire uncovered leading to short circuit, overheating, uncontrolled melting and even sudden ignition.

The insertion depth of each pipe into the fitting was also measured and the outer oxidized surface of each pipe removed to the required depth using a mechanical rotational peeling tool. The surface of each pipe then wiped with an alcohol wipe to remove any dust residue and other contaminants, a critical step to avoid any poorly welded joints.

To prevent pipe movement during the welding and cooling cycles which would adversely affect the welding process, the pipes and fittings were all clamped in place. Once these steps had all been completed the joints were then welded using an electrofusion welding machine for a specific amount of time relative to each fitting being welded.

Welds were then allowed to cool for a defined period of time to allow the unified melted pipe and fitting to cool down and solidify in a way that the material will regain the same flexibility and strength as it had prior to welding.

Ground loop pressure test

Once all welding was complete, a full pressure test of the completed ground loops was carried out to confirm the absence of any leaks. The test was completed in accordance with British Standards over a predefined period of time to allow for initial expansion of the pipework, the results of the satisfactory test recorded on a pressure test certificate.

Ground loop commission

The ground loops were flushed with water and filled with glycol and biocide prior to backfilling of the trenches taking place.

This involved checking the ground loop liquid was protected down to -10°C, using a refractometer.

Ground loop protection

The ground loops were then covered with a further 100mm of sand to protect them against any sharps in the backfilling material, again also ensuring good thermal contact between the ground loop pipework and surrounding ground.

Ground loop warning tape

Ground loop warning tape was laid in the trenches, 300mm below the surface, to warn any future excavation of the presence of the ground loops to avoid damage.

Field following ground loop installation

Once trenches had been backfilled with the previously excavated material, the top soil that had been set aside was then laid back over and the field re-seeded. Within a short period of time ground had fully recovered and the installation of the ground loops was no longer evident.

Ground floor insulation, moisture migration barrier & edge expansion

Unlike a traditional ground floor construction where the insulation is laid under the concrete slab, because underfloor heating was being installed a reverse slab construction was adopted. The insulation was then laid on top of the concreate slab prior to the screed being laid over it containing the underfloor heating system. The insulation directly under the screed prevents heat from the underfloor heating system travelling downwards into the concrete slab.

To prevent the screed covering the underfloor heating system reacting with the insulation sheet, a polythene moisture migration barrier was also installed.

To allow for expansion of the screed containing the underfloor heating system, edge expansion foam was installed around the perimeter or all rooms containing underfloor heating.

Ground floor underfloor heating manifolds

The ground floor underfloor heating manifolds were installed in position on the plant room wall ready to receive the underfloor heating circuits.

Ground floor underfloor heating castellation plates

Rather than tacking or clipping the pipework directly to the insulation, castellation plates were installed. These ensured accurate and uniform pipe spacing as well as suspending the pipes to allow complete screed coverage around their full diameter. The plates also protected the pipes from foot traffic reducing the possibility of damage before the screed was laid.

With the castellation plates in-situ, laying of the underfloor pipework circuits quickly progressed and once all the underfloor heating circuits were installed the accurate and uniform pipe spacing was evident.

Swimming pool perimeter underfloor heating

Underfloor heating to the perimeter of the swimming pool was installed so that the temperature of the floor is warm underfoot when entering and exiting the pool.

Due to the width of the floor, castellation plates could not be used, so a tacker system was reverted to.

Ground floor underfloor heating pipework tails and system fill and pressure test

Each of the underfloor heating circuits was returned back to the manifold location where they were meticulously cut to the required length and turned through 90° using pre-formed bends to ensure all pipes were uniform and unkinked before connecting them to their respective manifold.

Once all the circuits had been connected to the manifolds, the pipework was flushed, filled and pressure tested above its working pressure to ensure it was free from defects and leaks prior to being screeded over.

Ground floor underfloor heating completed manifolds

Each of the underfloor circuits was labelled so that the actuators could be correctly wired to the corresponding room thermostats during the electrical second fix.

First floor underfloor heating perimeter edging

Before the first floor underfloor heating routed gypsum fibrous boards were laid over the acoustic matting, all rooms receiving carpet were edged with 100mm wide by 18mm thick plywood. This allowed the thin 9mm think plywood over boarding to be securely fixed round the perimeter of the rooms ensuring there is no spring in the floor.

The edging further ensured that no pipework was present around the perimeter of the rooms where carpet grippers were installed which could have resulted in pipes being pieced by carpet fitters.

First floor underfloor heating boards

Once all the rooms requiring edging had been completed, the gypsum fibrous routed boards were laid and securely screwed in place to the floor decking beneath.

First floor underfloor heating end returns

End returns were installed along the edge of the underfloor boards to allow the pipework to uniformly return upon itself as it traversed the floor.

First floor underfloor heating pipework

With the underfloor boards and end returns in-situ, laying of the underfloor pipework circuits quickly progressed. The installation of the pipework then took place into the pre-routed groves within the boards.

First floor underfloor heating pipework tails underfloor heating fill and pressure test

Each of the underfloor heating circuits was returned back to the manifold location where they were meticulously cut to the required length and turned through 90° using pre-formed bends to ensure uniform and unkinked pipe before connecting them to the manifolds.

Once all the circuits had been connected to the manifolds, the pipework was flushed, filled and pressure tested above its working pressure to ensure it was free from defects and leaks prior to being screeded over.

Underfloor heating programmable room thermostats

The underfloor heating in each room of the property can be individually controlled by the Heatmiser programmable room thermostats allowing rooms to have different temperatures at different times of the day.

The Heatmiser thermostats are located adjacent to, and at the same height, as the room light switches for a neat appearance and convenient viewing and use. The thermostats are Wi-Fi enabled allowing the system to be controlled both locally and remotely via the internet using smart phones and tablets.

Mechanical Ventilation & Heat Recovery (MVHR) radial ducting

The radial ducting was installed to the MVHR design completed prior to installation commencing. Each room receiving its own supply or extract ducting.

Mechanical Ventilation & Heat Recovery (MVHR) plenums

The radial ducting was terminated in each of the rooms with a MVHR plenum allowing the flow rates to each room to be balanced on commissioning.

Mechanical Ventilation & Heat Recovery (MVHR) manifolds

The radial ducting to the rooms was fed from centralised MVHR manifolds served from the MVHR units in the plant room.

Each room being served by its own duct from a centralised manifold avoids the potential for ‘cross talk’ or smell between rooms which can occur with traditional ‘branch’ systems.

Because the ducts are one continuous length of pipe, the risk of air leaks in ceilings and walls from joints in branch ductwork is also avoided.

The radial system also has a very low air resistance meaning that the fans within the MVHR unit do not have to work as hard, potentially extending their lifecycle. The low air resistance also contributing to a quiet operation and more energy efficient system.

Mechanical Ventilation & Heat Recovery (MVHR) units

The MVHR units were located in the plant room for ease of access and servicing.

Mechanical Ventilation & Heat Recovery (MVHR) humidity sensors

Humidity sensors have been installed in each of the bathrooms and en-suites so that the MVHR system boosts the extract in these rooms when the relative humidity set point is reached.

The sensors have been neatly installed adjacent the underfloor air sensors that are linked to the programmable room thermostats outside of the rooms to comply with electrical regulations.

Mechanical Ventilation & Heat Recovery (MVHR) supply and extract ducting to outside air

A supply and extract hole for each MVHR unit was drilled through the plant room wall so allow stale air to be expelled and fresh air to be supplied.

Mechanical Ventilation & Heat Recovery (MVHR) supply and extract grills

Supply and extract grills were installed to neatly terminate the supply ducting to and from the building.

Fire suppression pipework

Loss Prevention Council Board (LPCB) approved fire suppression pipework was installed at the same time as the plumbing and heating first fix. The orange pipework is rated to resist heat in the event of a fire ensuring the sprinkler system operates as designed.

Fire suppression sprinkler heads

The concealed sprinkler heads were installed in strict accordance with the design drawings enquiring their location achieves full room area coverage in the event of a fire.

Fire suppression pipework pressure test

Upon completion of the fire suppression pipework and heads, the pipework was filled and pressure tested to 10 bar.

Fire suppression pump

The swimming pool was used as the stored water to supply the volume of water required to supply the system with the regulation 100 litres of water for 10 minutes in the event of fire. This avoided the need for the installation of a separate (additional) cold water storage tank  that would otherwise have been required.

A mains cold water pressure pump was installed in the pool plant room to pressurise the system to deliver the 100 litres of water per minute at the required pressure.

Fire suppression sprinkler heads completed

The concealed sprinkler head cover caps neatly conceal the heads out of sight in the ceiling finishes.

Plant room setting out

The plant room was marked out with where the pipework was to be installed prior to commencing.

Plant room incoming ground loop pipework

The incoming flow and return pipework from the ground loop geothermal manifold was converted to copper and a filling link installed.

This acts as an internal filling and flushing point for the ground loop as well as the external filling and flushing point in the external geothermal manifold chamber.

Plant room buffer tank

The plant room buffer tank, heated by the Ground Source Heat Pump (GSHP), provides a store of weather compensated central heating water serving the underfloor heating system.

This ensures that when the Ground Source Heat Pump (GSHP) is heating the hot water cylinder, there is no drop in temperature in the underfloor heating system.

Plant room hot water cylinder

The plant room unvented hot water cylinder, also heated by the Ground Source Heat Pump (GSHP), provides a hot water to all the bathrooms, en-suites, kitchen and utility sinks.

The hot water is distributed via a pumped hot water return system ensuring hot water is instantly available at the hot water outlets.

Plant room complete

With the plant room complete and the distribution system fully installed the final stage of the installation was to commission it.

The heating pipework was flushed and filled with water and inhibitor to protect it from corrosion.

Operating parameters, such as the weather compensation heat curve and hot water temperature were then set within the ground source heat pump controller and a commissioning certificate completed with all the commissioning readings and settings recorded.

Plant room labelling

Once the plant room installation was complete, all valves were clearly labelled to allow the customer, or anybody working on the system, to be able to easily and quickly identify them.

Plant room incoming ground loop insulation

The incoming ground loops from the external geothermal manifold chamber were insulated with Armoflex Class O insulation and also labelled.

Plant room electric metering

The ground and air source heat pump systems, hot water immersion element used only for legionella pasteurisation of the cylinder and the MVHR system were installed with dedicated electrical supplies and meters, clearly labelled.

Having dedicated electrical supplies and meters allows any electrical faults to be easily traced to the area of the electrical system containing the fault and for the accurate electrical usage of each system to be read.

Roof prior to PV installation

The property had a Catnic Urban standing seam roof. The tolerances of the standing seams were measured once the roof covering had been installed to ensure that the correct standing clamps were procured for the secure fixing of the panels to ensure the calculated wind and slow loads are resisted.

PV panel setting out

A string line was used to set out each row of clamps to ensure they were exactly in line.

PV panel standing seam clamps

ach of the standing seam clamps was tightened to the seam in accordance with the manufacturer torque settings.

PV panel earth bonding

The panels arrays were earth bonded to prevent the metal roof from becoming live in the event of a fault on the DC panel cabling.

PV clamp threads

Each of the PV panels was installed into position connecting the DC cables to the adjacent panels.

Once in-situ, the excess thread from each of the standing seam clamps was trimmed with the completed array aesthetics in mind.

PV panel flashings

Rubber end caps were fitted over the remaining threads and purpose made powder coated flashing installed to the top and bottom rows of the panel arrays to help blend the arrays into the roof.

PV panel arrays

The PV panel arrays have been spaced equally from the ridge line of the property, again for aesthetic appearance.

PV panel clean

The roof was cleaned of footprints and each of the panels cleaned to ensure they produced the maximum amount of renewable electricity from commissioning.

Completed PV arrays

The completed PV arrays were rigorously inspected both on foot and by drone before the scaffolding was dismantled.

Photovoltaic (PV) inverter, battery storage & Emergency Power Supply (EPS)

Two three phase SolaX hybrid inverters to maximise the conversion of the DC electricity generated by the PV panels to AC electricity for use was installed in the plant room. The inverter is Wifi enabled allowing the system to be monitored and managed both locally and remotely via the internet when away from the home through the easy to use application. The application facilitates the management and monitoring of the system allowing the customer to access key system data at anytime, anywhere. For example, being able to visualise and compare actual yields with those estimated is essential in ensuring the system is operating at peak performance.

SolaX battery storage was installed in conjunction with the inverter to maximise the self-consumption from the PV panels.

The batteries can also be force charged with cheap rate electricity from the grid during off-peak times when electricity suppliers offer cheaper tariffs. The cheap rate electricity can the be used the following day to power the home and heat pump system.

PV local isolators

Because the inverters and batteries were installed in a separate plant room to the electrical supply they are connected into, local isolators were installed to comply with electrical regulations allowing local isolation of the equipment for safety.

Emergency Power Supply (EPS) local isolator

A local isolator has also been installed in the plant room so the EPS to the fire suppression system can be locally isolated. The EPS ensures that the fire suppression system has electrical back up in the event of a power cut.

Completed living room

The completed living room heated by the ground source underfloor heating system, air handled by the mechanical ventilation and heat recovery system and protected by the fire suppression system.

Completed kitchen & dining

The completed kitchen and dining rooms heated by the ground source underfloor heating system, air handled by the mechanical ventilation and heat recovery system and protected by the fire suppression system.

Completed cinema room

The completed cinema room heated by the ground source underfloor heating system, air handled by the mechanical ventilation and heat recovery system and protected by the fire suppression system.

Completed gallery landing

The completed gallery landing heated by the ground source underfloor heating system, air handled by the mechanical ventilation and heat recovery system and protected by the fire suppression system.

A completed bedroom

The completed gallery landing heated by the ground source underfloor heating system, air handled by the mechanical ventilation and heat recovery system and protected by the fire suppression system.

A completed en-suite

The completed en-suite heated by the ground source underfloor heating system, air handled by the mechanical ventilation and heat recovery system and protected by the fire suppression system.

Completed swimming pool

The completed gallery swimming pool heated by the air source heat pump with the permitter  underfloor heating system heated by the ground source heat pump.

Air Source Heat Pump (ASHP) external unit

The air source heat pump external unit for heating the swimming pool has been located down the side of the property where it is out of sight so as not to detract from the building aesthetics.

Property nearing completion

The property nearing completion which has all its heating and hot water provided by the new Ground Source Heat Pump (GSHP) system, swimming pool water heated by the new Air Source Heat Pump (ASHP) system, electricity provided by the Photovoltaic (PV) and battery storage system, air  quality heat recovery provided by the Mechanical Ventilation & Heat Recovery (MVHR) system and a fire suppression system to protect the property in the event of a fire.