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Commercial Case Studies
Social Housing Case Studies
Design Case Studies


City West Homes


Eastlake & Tadema





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Works Completed

Removal and replacement of communal heating

Complete removal and replacement of communal heating and the individual hot water systems with new consumer heat interface units and smart meters in dwellings and the installation of a boosted cold water system.

Project involved:   

  • Maintaining heating and hot water services at all times with minimal disruption.

  • Maintaining mains cold water services at all times.

  • Replacement of Primary District Heating and HWS distribution pipework from the roof void to the dwellings.

  • Replacement and modification of in-flat heating and HWS pipework, including new radiators and connecting the new HWS supply to the existing system.


  • Installation of new Heat Interface Units (HIU) complete with smart meters.


  • Upgrade and replacement of cold water down service with a boosted system.


  • Removal of redundant services.


  • All associated builders work, decoration works and making good.

  • All associated Fire Stopping Works.


  • The installation of new inverter driven heating distribution pumps installed in a run & standby configuration.

  • The installation of a new buffer vessel.

  • The modification of control equipment and BMS panel as required in order to provide effective control of the new heating systems.

Details of plant room:    

  • Two Hoval Ultragas fired boilers with a combined heat output of 1000Kw provide a constant supply of LTHW @ 80°C to a 1500L Buffer Vessel.


  • Drawing heat from the Buffer Vessel for distribution to the district heating network are four Grundfos TPED 50-290/2 BQQE Inverter driven pumps. The pump speeds are controlled by differential pressure sensors installed at the index points in the heat network.


  • Primary heat is measured within the Heat Interface Unit by a Sharky M-Bus Heat Meter that relays its information to data loggers that transmit through a wireless network to City West Homes’ energy monitoring and billing platform.

Details of size:   

  • We installed 1,200 meters of distribution pipework ranging between 28mm and 100mm diameter.


  • This pipework, starting at the energy centre and rising to the roof space within both blocks, provides the primary LTHW distribution. From here we installed 22 risers feeding 108 dwellings.

  • The system has been designed and commissioned on Differential Pressure (DP). This is held at a constant at all four index points within the heat network, situated at the bottom of the furthest risers. Changes in demand are picked up by the sensors at the index circuits and change the output of the variable speed driven pumps to maintain a constant pressure of 35kPa under varying conditions.


  • We have installed a heat meter to each HIU to record and measure the amount of district heat taken from the network. We have utilised the landlord’s electrical supplies to ensure all electrical power used to drive and monitor the heat produced within the HIU is paid for by the landlord, as was the case in the existing district heating system. Each heat meter is wired back to central hubs where data stream loggers collate the information before transmitting to City West Homes’ energy monitoring and billing platform.


  • This project has cost saving benefits through efficiency measures to the residents and environment. Residents have gone from a 24 hour LTHW constant flow domestic hot water system with no control over hot water temperature or heating. The newly installed HIUs utilise a new boosted cold water supply providing a pressure range of 1.5bar – 2.5bar set with an output of 18L/m of hot water production.


  • Single panel and double panel radiators have been replaced with new efficient convector panel radiators each supplied with a thermostatic control valve. The heating system is now Part L compliant with a controlled/ interlocked 7-day programmable room thermostat and pipe insulation throughout.

  • Based from the feasibility study undertaken the environmental benefits are predicted as:

    • A reduction in gas and electricity.

    • Reduction of energy usage across the estate by 35%.

    • Direct financial savings to residents in the region of £37,800 in gas consumption per annum, greatly assisting residents that are currently in fuel poverty.

    • Reducing Westminster’s carbon footprint for these blocks by an estimated 235,000 kg/Co2.


L & Q Group


Georgefield House




September 2016

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Works Completed

Gas Main Renewal

Georgefield House is a General Needs Residential Housing Block managed by L&Q Group and is situated in Rickmansworth, Hertfordshire. The property has 20 individual dwellings each served by a domestic gas supply from meters within an underground gas meter compartment. A proportion of pipes had signs of advanced corrosion requiring urgent replacement. The client provided a works instruction for the replacement of 12 gas pipes. The challenge was accessing the corroded pipes as they were situated behind other gas supplies that were not affected. A detailed plan was drawn up to ensure minimum disruption for the residents during the replacement period. This was achieved by adopting a phased approach relating to occupancy type, usage of supplies, i.e. hot water type and cooking facilities per dwelling. 8x flats were completed within a working day while the other 4x within 36 hours.

On Solution

  • 12x urgent gas supply conversions

  • Planned programme of works

  • Minimum disruption


  • Hazard removed

  • Long lasting pipe work

  • Greater organisation for future maintenance


City West Homes


Wharncliffe Gardens Estate




2016 - 2017

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Works Completed

District Heating & Flat Works (P133b)

Wharncliffe Gardens Estate comprises of 288 dwellings spread over 11 blocks. Approximately 47% are private leasehold, with the other 53% occupied by residents of City West Homes.


The original heating and hot water systems comprised of a ‘Harco-Pack’ utilising a 117 litre indirect copper cylinder and tap-stat. The heating zone valve was controlled by a mechanical room thermostat that served radiators through a one-pipe system.

A single boiler house comprising of four gas fired boilers each rated at 570kW, provided primary district heating to three satellite plantrooms. This buried pipework that served these plantrooms was approximately 40 years old, leaking and in disrepair. The works consisted of modifying the boiler room Low Loss Header to incorporate the installation of a new district underground manifold. Modifications were made to each satellite plantroom to accept the new size pipe work. Plate heat exchangers then transfer the load from the primary to the secondary district heating circuits serving all dwellings with heating and hot water.


A trench was excavated from the boiler room to each satellite plantroom to carry the new district heating pipework. Casaflex™ Uno, manufactured by Brugg Pipe Systems, was specified and delivered in 120 meter bundles. Given the external pipe diameter of 202mm and each coil weighing over 1 tonne, we designed a bespoke turntable capable of carrying the load and uncoiling it safely into the trench. In total over 0.6km of Casaflex™ pipework was laid.


288 Heat Interface Units (HIU) were installed with individual heat metering. The heating system is controlled by programmable room thermostat and thermostatic radiator valves (TRV) with hot water delivery of 44kW (35⁰C rise @18 litres/min).

All heat metering information is collected via cable from each HIU meter into hubs strategically placed around the estate. This information is transmitted via wireless connectivity to CityWest Homes’ centralised hub for billing purposes and energy monitoring.


To ensure each HIU had an adequate water flow of 18 litres/min and a minimum 2.5 bar pressure the water mains across the estate had to be upgraded. This was achieved by installing 1km of MDPE underground pipework throughout the estate, terminating with external isolation valves; 84 new copper risers were installed across 11 blocks and 288 flats. To facilitate this phase of the project we had to excavate a large proportion of the site which in turn required a comprehensive traffic management and pedestrian plan. We collaborated with Thames Water Development Services, the utility company responsible for the City of Westminster highway connections.

  • H&V nominated District Heating Project of the year 2017

  • L8 Chlorination and legionella compliant

  • Individual remote smart metering

  • Collaboration and management of various utility service providers with pro-forma payments


  • Heat Networks (Metering & Billing) Regulations 2014 compliant

  • A 20% percent increase in efficiency with a cost saving of £30k in year one alone


  • High level of customer satisfaction in comparison to all other major works – 82% in comparison with 59%

  • Greater system performance for end users with an increase of hot water delivery from 4 litres/min to 18 litres/min


St Albans City & District Council


Marford Road Solar Upgrade




8 Weeks 2016

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Works Completed

16 solar thermal systems over 8 week period
Smart eBus energy efficient controls
EPC, MCS registration and commissioning

Watret has a long-standing relationship with St Albans City & District Council, managing in the region of 6,000 properties in St Albans city centre and surrounding villages. The council required an upgrade to a selection of solar thermal systems within their housing stock.

Residents were reporting myriad issues with the generation of hot water from the current solar thermal system. The existing installations consisted of numerous manufacturers, many of whom were no longer trading.

Our initial investigation highlighted that the solar panels were no longer working effectively, with signs of leakage and weathering within the collectors. Other design issues were found; the drain back system had been incorrectly installed with insufficient head height and cylinders were twin coil copper design with low storage capacity.

We upgraded all thermal systems by fitting new collectors with pressurisation of the system through bespoke unvented twin coil solar cylinders which provided an increased capacity and greater temperature control. This consisted of providing a total Vaillant solution cleverly utilising the existing gas boiler. E Bus connectivity allowed all heating controls to be linked together providing end users with optimum efficiency.


  • Premium and improved system design that works for end users

  • 10 years manufacturer’s warranty

  • Long-term maintenance agreement

  • Cost savings

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Richmond Housing Partnership (RHP)


Peldon Court




10 months 2015-2016

Works Completed

CDM Contractor F10 Notification

Customer-Focused Project

Up to 9 properties completed per day

Comprehensive Site Management

Completed six weeks ahead of schedule

Conversion of district heating to individual gas fired central heating systems


RHP is a social housing provider in the region of 6,000 properties within the Royal Borough of Richmond upon Thames. The site environment was 4x individual tower blocks fed from a central boiler house with constant temperature heat supply only. During the consultation pre-construction phase the client and stakeholders decided to decommission the existing communal plant and deliver individual gas supplies consisting of gas fired system boiler complete with unvented hot water cylinder and radiators.

As Principle Contractor we developed a Phased Construction Plan to incorporate the many different aspects of the project. Phase one involved connecting new gas services pipes to the underground distribution network. 12 service pipes in total vertically run to serve 96 properties. Watret brought forward the installation of boilers and flues utilising the existing scaffolding for the purpose of making good of the flues and discharge pipes reducing costs and minimising any inconvenience to residents.


  • Part L energy efficient systems

  • Cost saving on distribution pipes

  • Renewing of gas service and supply pipes

  • Resident autonomy over energy usage with independent billing

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Paradigm Housing


TracPipe® replacement Honeycroft Hill House, Uxbridge




April – May 2017

Works Completed

TracPipe® replacement

The existing gas installation was a pipe-in-pipe system using TracPipe® which is sleeved between the meter position and the AECV within each dwelling. The system had been operational for around 19 months, but a number of external gas leaks were reported and detected within the pipes. These were attributed to flux contamination of the internal services of both the TracPipe® and the transition fittings at the meter positions, causing premature failure of the TracPipe®.

The site has 37 gas meters in total, situated within the garden area at the front of the building. The gas installation pipework between the meters and the AECV in each dwelling is between 28mm and 50mm diameter, within a soft dig area.

On exposing all the pipe work clear routes were determined with adequate inspection chambers to accommodate the new connections. Systematically we organised access to each dwelling and laying of all new pipework with timely cross overs. The pipes were sufficiently labelled to each property for ease of future maintenance.

The site was in a high traffic public area with the constant flow of care workers assisting numerous vulnerable residents which made it important to maintain a good level of security and safe guarding. The works area was sectioned by clear fencing. Engineers transferred waste material via clear routes and only when one section had been backfilled did we move on to the next area of the dig.

Six inspection chambers were constructed to house the connections, one of which was designed to house 20 connections.

The excavated area was then reinstated with a soft sand base, pipe identification and MOT Type ‘A’ levelling material for new paved area. This newly paved area ensures safety and easier access to the gas meters for any future maintenance, reading and topping up of credit.

On Solution

  • High level supervision and risk management from works being carried out in public area

  • 50% of the properties were of Supported Housing Residents

  • Logistical planning of access arrangements

  • Safe movement and responsible disposal of contaminated waste


  • Sound new gas network tested and certified with detailed drawing plan

  • Improved access for planned and reactive maintenance

  • Resident peace of mind and confidence in new gas supplies