Heating and Ventilating

Innovation and ingenuity are helping to save money and save energy in the social housing sector, according to Peter Gammon

Solar, thermal, photovoltaic and heat pumps all have their part to play in saving energy. However, there is another way to deliver energy efficient central heating and hot water to social housing tenants which is gaining in popularity - district heating. The idea has been around for a long time and provides the building services engineer the ability to generate plenty of heat and hot water, while taking a sustainable and energy efficient approach.

At its simplest, a central heat source (such as boilers or a CHP unit) is networked to a group of flats or homes. A networked heating substation draws heat from the central boiler plant or CHP system via a simple LTHW loop. It then delivers all the functions of a boiler - providing heating controlled by the occupants via a programmable room thermostat and instantaneous hot water.

The main benefit of such a scheme is that output of the centralised system is typically lower than the aggregated output of individual systems. Calculating individual bills is also made easy with a built in heat meter, as well as the option to incorporate water meters and prepayment systems.

So what's in it for the providers of social housing? One of the major advantages is the ability to eliminate the gas supply to every home. If you don't have to install individual boilers in each dwelling within a development, you drastically reduce the material and labour costs associated with heating and hot water delivery. Another problem - which district heating solves - is that of flueing each dwelling. It also deals with the unsightly pluming effect of condensing boilers and eradicates the problem associated with condensate waste from individual condensing appliances.

The absence of gas in the units also means engineers without Gas Competency certification can carry out maintenance and inspections periodically, again reducing costs. The units are also easy to site - they're small and, because they don't need a flue, they can be installed virtually anywhere within a building. This gives the building services engineer greater flexibility and the ability to maximise space. As you would expect, heat interface units can be used with either radiators or underfloor heating and some models can even be weather compensated if required.

New technology and control systems enable tenants to get all the benefits of their own central heating system - and all the cost and maintenance savings of a networked heating scheme. For example, it is now possible to incorporate a self-contained heat interface unit with an integrated unvented stainless steel storage cylinder. This allows tenants to enjoy completely independent control of their heating and hot water.

Heat interface units are the best of both worlds - the energy efficiency and easy management of a district heating scheme combined with plenty of hot water when the occupliers turn on the tap. Plus, should there be a breakdown in the central plant, the tenant will still have hot water stored for their use until the plant is up and running again.

What's more, by fitting a self-contained heat interface unit with an integrated unvented cylinder, you're also putting a reduced load on the primary (black) system. This ensures the system can be run efficiently and the load can be managed effectively - again keeping both energy consumption and fuel bills down.

// The author is technical manager at MHS Boilers //