Further Guidance
Where available, data from the HARP database or certified data values should be used for the gross efficiency of gas, oil, or solid fuel room heaters, as explained in Appendix E. If not using certified data or data from HARP, room heater gross efficiency should be taken from Table 4a.
The following notes provide guidance for identifying the appropriate entry from the room heater section of Table 4a, for gas fires already installed in a dwelling.(They are not intended to classify gas fires for testing purposes.)
Gas fires can be open or closed fronted. Open fronted means the fuel bed and combustion gases are not sealed from the room where the gas fire is fitted. Such a fire may or may not have a glass panel in front of the fuel bed, but the glass panel is not sealed to the front of the fire. Closed fronted means the fuel bed and combustion gases are sealed (generally with a glass panel sealed to the front of the fire) from the room where the gas fire is fitted.
Fuel effect gas fires can be live fuel effect (LFE), inset live fuel effect (ILFE) or decorative fuel effect (DFE). The products of combustion from a DFE pass unrestricted from the fire-bed to the chimney or flue; for the LFE/ILFE the products of combustion are restricted before passing into the chimney or flue. For further clarification of LFE/ILFE/DFE, see clauses 3.1.2, 3.1.3 and 3.1.4 and Figure 1 of BS 7977-1:2002.
Gas, oil, and solid fuel room heaters may have a boiler providing either domestic hot water only or both space heating and domestic hot water.
For gas back boilers, separate efficiencies apply to the boiler and to the associated room heater. This means that:
For oil and solid fuel room heaters with boilers, the gross efficiency is an overall value (sum of heat to water and heat to room).
For other systems, the seasonal efficiency is taken from Table 4a. For systems not covered by the table, seek guidance from SEAI.
In cases where the burner unit is replaced, non-default efficiency values must not be used. Default efficiency should be selected from Table 4a or Table 4b in the DEAP manual. The original boiler age and the replacement burner fuel type should be used.