London Heating Services

  • Central Heating Guide
  • C/H Controls Introduction
  • C/H Thermal Controls
  • C/H Valve Controls
  • C/H Function Controls
  • C/H System Replacement
  • C/H Controls Installation
  • Energy efficient home
  • Central heating replacement & Upgrading system info

    Many existing wet central heating systems are of obsolete design and are poorly controlled. Poor design features that should be improved are:

  • gravity circulation to the hot water cylinder stored water is slow to re-heat
  • no cylinder thermostat excessive stored hot water temperatures
  • no room thermostat excessive room temperatures
  • no boiler interlock boiler keeps hot unnecessarily during programmed periods of heating and hot water.

    Where possible always upgrade at least to the minimum set of controls. Where it is not possible to convert to full pumping, the following system will provide many of the energy efficiency benefits:

  • cylinder thermostat
  • room thermostat (or programmable room thermostat)
  • standard programmer (or programmable room thermostat)
  • one two-port motorised valve fitted on the gravity flow to the hot water cylinder
  • TRVs on all radiators except in rooms with a room thermostat
  • boiler interlock

    The main benefits of improved controls for warm air systems are gained when the air heater is replaced. Most modern air heaters include controls that vary the firing rate as well as controlling the air fan speed, which reduces noise and provides a more even temperature.

    The options for upgrading the controls used with existing electric storage heating systems are limited, because the improved controls are usually integral to the appliances or designed specifically for use in modern appliances. However, an external temperature sensor can be fitted that adjusts the charge taken in accordance with external temperature.

    It is not practical to update controls used with older-type storage heaters. Replacement of the system with the integrated CELECT-type system (see page 9) can be considered. Significant running cost benefits are possible using modern storage heaters, which have improved integral controls such as automatic charge control and/or fan/damper controls.

    Upgraded system retaining gravity domestic hot water
    Pic: Upgraded system retaining gravity domestic hot water

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