¶ Group Heating Examples
In group heating systems in DEAP, the "percentage of heat" entry for “heating systems 1/2/3” is the percentage of heat received by the dwelling from the group heating scheme boilers / heat pumps and is not reduced when CHP or secondary individual heating are present. This percentage of heat column only represents group heating appliances providing heat only (and not electricity). Therefore, it does not include the portion of heat from CHP plant (which also generates electricity) or secondary heating (which is not part of the group heating scheme - it is in the dwelling).
¶ Examples and corresponding DEAP entries for group heating systems
¶ Example 1
A single boiler (90% efficient; mains gas fuel) in the group heating system. No other source of heat (from CHP or secondary heating) is present. The distribution loss factor for the group heating system is taken from the DEAP manual Table 9. The "Percentage of heat" is 100% for this boiler as it is the only group heating boiler present as shown in the following illustration:
¶
Example 2
Same as (1) above but with the addition of another boiler (92% efficient; oil) which supplies 40% of the heat from group heating boilers. Therefore, the mains gas boiler supplies 60% in the "percentage of heat" column and the oil boiler supplies 40% in the “percentage of heat” column.
¶ Example 3
Same as (2) above but the dwelling itself also contains an open fire which is a fixed room heater. The "percentage of heat" column must ALWAYS total 100%, so the addition of the open fire (Secondary system) does not reduce the percentages of heat from "Heating System 1" or "Heating System 2". When the Percentage of Heat column does not total 100%, DEAP 4 flags this with a red warning sign.
Refer to Table 7 of the DEAP Manual for guidance on the fraction of heat supplied by secondary heating systems. Percentage of heat from secondary is therefore 10%:
¶ Example 4
Same as (3) above but with a CHP system supplying a fraction of 0.2 of the heat. The percentages from the secondary system and heating systems 1 and 2 are not reduced when the CHP system is added as detailed above.
¶ Example 5
Finally, take a system the same as (4) above, but add a solar space heating system. It is determined using the methodology referenced in Section 12.1.2. Solar space heating system is 20% of the heat output from "heat-only" plant. Therefore, this is entered as per the following diagram, and each of the percentages from Heating system 1 and 2 are reduced by 20% of what they were prior to addition of solar heating.
The Percentage of Heat column still must total 100%.
