Sep 19, 2018 Last Updated 8:58 AM, Sep 17, 2018

Uponor has been specified for a renewables-based scheme at a social housing project in Norfolk

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Dave Playfoot, Applications Manager from heating, cooling and plumbing specialist, Uponor, discusses the energy efficiency and management benefits of a renewables-based district heating installation at social housing apartments in Norfolk.

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District heating and cooling installations are proven in a variety of residential and commercial settings. In social housing environments, where housing providers are looking for solutions that will both address the issue of fuel poverty and enable servicing and maintenance regimes to be carried out without having to gain access to individual properties, they are becoming increasingly popular. What’s more, thanks to their suitability for use with renewables and extended service life, they can demonstrate tangible carbon reduction and cost viability benefits, which provide an excellent return on investment.

A recent project at Flagship Group’s Orchard Close in the south Norfolk village of Watton demonstrates why. Flagship decided to replace tenants’ existing Economy 7 electric storage heaters using a ground source heat pump as the main energy source and pre-insulated Ecoflex pipe from Uponor as the underground infrastructure. The resulting improvements have reduced customers’ heating bills by two thirds while ensuring consistent, reliable and sustainable on-demand heating and hot water with individual control and metering for every property on the estate.

Cost and management benefits

Orchard Close is a cul-de-sac of 30 flats, and the original Economy 7 heating system had been installed in 1986 to enable occupiers to access cheaper electricity tariffs. However, the system was inefficient and expensive to run, becoming increasingly onerous as energy prices have risen. Moreover, with storage heaters in every property, Flagship’s maintenance teams had to gain access to each property for annual checks and routine maintenance.

As part of the company’s Wellbeing Plan for continual improvement in energy use and carbon emissions, Flagship began to consider a district heating system as an alternative. By opting for a system powered by ground source heat pumps, the housing provider was able to qualify for the Renewable Heat Incentive (RHI). Capital investment funded the project from Flagship with the RHI contributing towards the cost of the scheme.

The project was initiated to help reduce tenants’ fuel bills, encouraging them to heat their homes and benefit from a more comfortable living environment with less risk of damp and poor air quality. However, reduced management and maintenance for Flagship, and longer replacement intervals, with the district heating system expected to last three times longer than a conventional boiler, also added up to a very attractive business case for Flagship.

Efficiency and reliability

Flagship turned to renewable heating specialist, Finn Geotherm, to design, specify and install the district heating system and the company selected two 60kW Lampoassa ground source heat pumps, linked to a 2400 litre thermal store. Twin heat pumps and a thermal store were specified to build resilience into the system, enabling Flagship to carry out maintenance without taking heating and hot water services offline. This ensures that residents never have to wait in for a maintenance visit and provides confidence in a reliable, low-cost 24/7 heating and hot water supply.

All the equipment is located centrally in an external plant room, where Ofgem heat meters provide the data for RHI requirements. Alongside the centralised plant, each flat has its own heat interface unit (HIU) to transfer the heat energy to the local hot water radiator circuit and a hot water tank in the property. This has been connected to individual meters for each flat to ensure that tenants are only billed for the heating and hot water they actually use.

Ease and speed of installation

To connect the centralised plant with the individual flats, the system relies on a network of insulated pipes for flow and return from the plant room to the properties. Finn Geotherm specified Uponor’s Ecoflex pipe to create this infrastructure, along with the Uponor Q&E Shrink-Fit System pipe connectors. This enabled heat loss within the primary distribution circuit to be minimised, scoring against Finn Geotherm’s objective of achieving maximum system efficiency.

A total of 220m of Ecoflex was installed, with 50mm pipe used for the main spine and 32mm pipe used to create the localised connections to the properties. Speed and ease of installation of the pipe network was mission-critical because all the properties remained occupied during the project and heating and hot water services had to remain operational while the project was completed.

Rapid and accurate pipe supply was critical in this regard, as was the use of Uponor’s Q&E Shrink-Fit System fixings, as every property required two tee joints to connect the HIU to the infrastructure. The Q&E fittings helped the installation team to ensure the integrity of every joint while speeding up the installation and reducing the cost of the infrastructure.

Using a special tool provided by Uponor to expand the end of the pipe, the Finn Geotherm team was able to insert each fitting and connect two pieces of Ecoflex pipe, which then sealed tightly around it. Uponor provided training for the Finn Geotherm team, enabling them to maximise the benefits of the Q&E Shrink-Fit System on site.

Installation of the underground district heating networks was sequenced to minimise disruption to tenants with individual paving stones and sections of turf lifted to enable the pipework infrastructure to be laid, then carefully replaced afterwards.

Service life

The district heating system at Orchard Close is now complete and fully operational, with an anticipated service life of 35 years. The Ecoflex pre-insulated pipe infrastructure, which bends and flexes with the natural ground conditions, will remain serviceable with zero maintenance for even longer than the plant.

Ecoflex solutions have been proven in district heating projects for more than 20 years, ensuring Flagship and its tenants can be confident of a long-term, low-maintenance and energy-efficient solution to the heating requirements of these apartments.

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