Appendix F¶
Electric CPSUs¶
An electric CPSU is a central heating system providing space and domestic water heating. Primary water heated mainly during low-rate periods to up to 95°C in winter is stored in a thermal store. If the CPSU volume is less than 270 litres, the resulting high-rate fraction can lead to a poor SAP rating.
The procedure in this appendix applies for a 10-hour off-peak tariff providing 3 low-rate periods per day. It is not valid for other tariffs.