BSEE DOMESTIC & RESIDENTIAL
High rise buildings pose a unique set of challenges when it comes to installing and operang heang systems. But there is a technology that can help ease the burden, as Richard HansonGraville, Technical Manager at Thermal Integraon Ltd, explains.
they are fitted in individual flats. That’s why centralised heating systems such as district heating schemes (also known as communal or community heating, or heat networks) are gaining in popularity among developers and building owners.
H
With district heating, the heat for an area – say a tower block – is produced centrally, and hot water or steam is transported to the buildings through a network of pipes. This network is simply a means of transporting the heat from the primary heat source to the users of the heat.
uAt the core of the technological revoluon in HIUs is the shi from mechanical to electronic systems.
The advantages afforded by the economy of scale this approach offers are huge. If designed and installed correctly, energy efficiency is increased, fuel consumption is lower because of central plant efficiencies, harmful carbon emissions are reduced, access for maintenance is made easier, heating cost per household is lower, continuity of service is improved, space is saved, and the management of supply and demand is simplified. Because individual dwellings in a high- rise block don’t require their own boilers, the explosion risk associated with a gas distribution pipework is much reduced, as is the need for individual flue terminals. Meter reading and energy billing can be carried out remotely and annual gas safety inspection is typically restricted to the plant room. Moreover, several different fuel sources can be used in a centralised scheme serving a multi-occupancy building, and significant environmental benefits can be delivered by adopting low carbon and renewable technologies such as biomass, solar thermal water heating, CHP, and commercial heat pumps that far out- perform their domestic equivalent. A key component of district and communal heat systems is the heat interface unit (HIU). This is a self- contained system that typically provides domestic hot water and central heating in properties connected to a district heating system using a central boiler. A typical HIU comprises several components including a heat exchanger, pipework, valves and a heat meter.
eating systems in residential high-rise buildings can prove expensive – both in terms of installation and maintenance – if
Adversing: 01622 699116 Editorial: 01354 461430
RENEWABLE HEAT FOR HIGHRISES The many benefits of district heang systems
HIUs can be installed within each individual dwelling, or in the dividing wall between each dwelling and the ‘landlord’ space, the latter providing easy access for inspection and maintenance.
One potential problem with HIUs and, indeed, district heating in general – especially in high-rise residential applications – is heat loss. To ensure that hot water is available without delay, HIUs draw a trickle flow of hot water from the primary supply to overcome heat losses and this almost always runs continuously. This is most keenly felt in properties fitted with pre-pay systems where users can find their remaining credit quite literally draining away when the property is unoccupied.
There are, essentially, three ways to reduce heat loss: uInsulation – our own HIUs, for example, use expanded polypropylene moulded enclosures that encase individual components, supporting assemblies and prevent heat bridging to the environment. Heat losses can be reduced to less than 1p a day. uAllow the system to go cold when not in use – many electronic HIUs provide an optional ‘economy mode’ where the HIU will go cold after an hour of inactivity. uRun the network at lower temperatures – such as 65ºC flow, and an average annual return temperature under 20ºC.
Electronic HIUs are reliable. Our own controller, for example, has operated in the field for many years, with thousands sold and with no recorded failures. On top of this, occupants are charged for units of heat rather than units of gas and the HIUs typically come with heat meters to measure energy use. However, some properties require exceptionally high hot water loads, and this is where thermal stores or unvented cylinders come into play. They enable far higher instantaneous loads to be met while reducing the loads on the central heat source.
A thermal store allows various heat sources to work in harmony with each
24 BUILDING SERVICES & ENVIRONMENTAL ENGINEER JULY 2018
other. It can be used to drive both hot water for taps and central heating. In our case, there is also a plate heat exchanger option to generate mains pressure hot water to run multiple bathrooms using high pressure mains water without the need for unvented certification, annual maintenance, or discharge pipes.
Further options provide fitted controls for the use of local boilers of all types (sealed and vented) as well as heat pumps. Control options include pump assemblies, thermostats, programmers and timers, and control valves. Both radiators and underfloor heating can be run simultaneously and the thermal store is configured so that low temperature loads like underfloor heating can run off low temperature heat sources such as heat pumps while high temperature loads, for example radiators, run using higher temperature heat sources like wood burners or boilers.
www.heatweb.co.uk Advances in HIU technology
revolution in HIUs is the shift from mechanical to electronic systems. The ability of electronic systems to deploy advanced control strategies, using just the one valve per circuit, makes them more advanced without the need to add more and more valves (or valve components).
A
The introduction of electronics also enables networked communications, including remote management of settings, remote fault alarming, and holistic control of heat network functionality.
t the core of the technological
All the hardware is usually already in place to allow this networking to take place in the form of a billing system. However, the real breakthrough that has been made in the HIUs, enabled by the use of electronics, is the way the systems manage the volumes and times that primary heat is drawn in order to manage the heat network in its entirety. The positive effect on heat loss and volumes circulated is enormous. Furthermore, HIUs are now covered by an independent performance standard under contractors’ organisation Building Engineering Services Association, to guarantee performance. Visit:
www.thebesa.com/ukhiu VISIT OUR WEBSITE:
www.bsee.co.uk
uThe HIU typically provides domesc hot water and central heang in properes connected to a district heang system using a central boiler.
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50