Buffer Heat Store

Buffer Tank


It is a recommendation that a buffer or accumulator tank be incorporated as part of domestic wood pellet / multi fuel boiler system installations where appropriate.
A buffer or accumulator cylinder in a domestic biomass heating installation is a primary heat storage/distribution cylinder, which is heated by the boiler to a set temperature and can store the resulting high temperature water for long system standstill periods, until heating or hot water is required.
A buffer / accumulator reduces the on/off cycling of  boilers by “smoothing” the heat output to the dwelling.
The buffer or accumulator capacity should be calculated in accordance with your manufacturer’s recommendations.
A rough guideline for establishing the volume of the buffer is in the region of 55 to 65 L/kW of the rated boiler size.

The use of a buffer / accumulator is noteworthy in the following situations:

  • Where the boiler does not have full modulation capabilities: the use of a buffer will smooth the heat output to the dwelling.
  • In situations where the boiler is not capable of supplying the full heat demand of the house, a buffer tank will allow the boiler to run for longer at optimum efficiency extracting maximum potential from the boiler and fuel.


Wood Gasification Boiler Requirements

A buffer store (accumulator) will be installed in conjunction with your wood gasification boiler to ensure the efficient operation of your boiler. Buffer stores are important heat storage devices, especially for wood gasification boilers. These boilers can only be operated efficiently when combined with an accumulator since controlled operation at part load is more difficult.

Solar Thermal System Requirements

The maximum aperture area supported is 6m2 for both flat plate and evacuated tube panels.
The following recommendations are made regarding the sizing of the hot water cylinder based on maximum cylinder temperature:

  • At 60°C use a minimum of 70 litres per m2
  • At 85°C use a minimum of 50 litres per m2

Heat Pump System Requirements

When installing a heat pump into an existing dwelling it is critical to ensure that the building is sufficiently insulated and the existing heating system is surveyed for compatibility. In many cases the dwelling’s fabric will need to be upgraded to ensure efficient operation and thus optimal electricity cost. It is recommended to try and achieve insulation levels as close to “new build” requirements, where possible and practical. Recommended values for average elemental U-value for insulation would be:

  • Roofs 0.16 W/m2K
  • Walls 0.27 W/m2K
  • Ground Floors 0.25 W/m2K
  • Exposed Floors 0.25 W/m2K
  • External doors windows/roof-lights: 2.0 W/m2K