A warning that domestic hot water (dhw) quality is being compromised in multi-residential buildings through inadequate control has come from manufacturer SAV Systems.
SAV sales director Jan Hansen said: 'The main problem lies in the use of heat interface units (HIUs) that lack useful control functionality, as this results in lack of responsiveness and poor temperature control of dhw.

'For example, if there is no differential pressure control or effective thermostatic control in the HIU, then the temperature variation of the dhw can be as much as +/- 15 deg C. So in a system designed for a dhw temperature of 50 deg C the actual temperature could range from 35 to 65 deg C. This is clearly unacceptable.

'Such units are often installed because they are seen as being relatively cheap, but if they lead to frequent call-backs and a dissatisfied client they can, instead, prove to be a very expensive solution. This really is a case of spoiling the ship for a ha'porth of tar.'

Mr Hansen concluded: 'Historically, HIUs within district heating schemes have been treated as accessories rather than a key element within the system. This is something that has to change if we are to avoid disappointing the end user and embarrassing the specifier.'