FAQ:Individual Control

Q1 Our tenants / homeowners complain about the lack of control of heat supply in existing centralised schemes. How much does it cost for a centralised system (such as the old ones we currently have) to be upgraded to individual controls in each residential unit?

Q2. Can all systems be upgraded this way?

Q3. What are the technical restrictions when considering connections of existing buildings to district heating networks?

Q4. Or is it just an issue of cost?

A1. The upgrading of an existing centralised (communal) heating system to allow for individual controls in each residential unit
can be as simple as involve installing thermostatic controls on each of the radiators or at the main connection to the unit and the installation of an on/off valve controlled by a room thermostat and timeclock/programmer.

For new schemes packaged Hydraulic Interface Units (HIUs) are generally specified and these can be retrofitted into existing communally heated properties. They have the appearance of a small domestic boiler and generally contain automatic primary system balancing equipment, hot water services heat exchanger, heating heat exchanger, pump and associated controls. They are not always the most appropriate solution for existing buildings where a simpler and much cheaper arrangement may be adequate.

The cost of upgrading systems varies significantly depending the extents of the work but some indicative costs for are as follows:

Control valve and programmer/room thermostat £400
Hydraulic Interface units £1350 - £2000 each
Addition of a heat meter £150 - £400

A2. Each system should be surveyed to assess the potential for upgrading and the likely costs of upgrading. Hydraulic Interface Units (HIU) are compact units which include all the necessary controls and metering for communal systems and are relatively simple to retrofit into an existing system. Alternatively, thermostatically controlled radiator valves, heating on/off valve and flow meter can be installed to allow simple control and metering at much lower cost.

A3. Certain system are not compatible with district heating systems, such as electrically heated buildings or those with steam systems. However, wherever a building uses a hot water distribution system for heating (and ideally hot water production also) there is the potential for it to be connected.

However, retrospective connections of buildings to district heating schemes are rarely straighforward and very often modifications will be needed to the secondary/building system. Typical technical restrictions relate to the following:

hydraulic design of the existing building heating system (particularly operating temperatures)
the location of the existing boiler plant and availability of space for district heating plant (heat exchanger, meter etc)

A4. As discussed above, there are circumstances that would mean that a connection to a district heating scheme required a complete replacement of the building’s heating system (e.g. electrically heated buildings). However, generally speaking most of the issues that arise from otherwise ‘compatible’ connections translate into cost issues. However, it is to be noted that in some instances the additional cost to overcome a problem is so high to render the connection not viable.