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6.04 LTHW boiler efficiencies

Solution The following hierarchy should be followed to establish suitable values for the ‘Effective Heat Generating Seasonal Efficiency’ for all boilers.
1. Use ECA product list part load values at 30% and 100%* - these should be used to calculate the seasonal efficiency as per the Non Domestic Building Services Compliance Guide (NDBSCG).
2. Use ECA product list full load value* (when part load values are not given).
3. Use current SEDBUK values where available.
4. Use either manufacturer’s information* or ‘boiler plate*’ information or information from manufacturer’s technical helpdesk*. Where a gross efficiency value is established for a non condensing boiler then a deduction of 0.05 (i.e. 5%) should be made to it to convert it to an appropriate seasonal efficiency.
5. Use SAP tables (up to 70kW output).
6. Use suitable SBEM default; it is essential for the site notes to provide evidence as to why the above methods were not used to obtain a more accurate value, i.e. by providing evidence of failed attempts.
In addition to any boiler efficiency values established from the above the relevant heating credits should be added by following the guidance in the NDBSCG.

*Net efficiencies/values must be converted to gross efficiencies as per the NDBSCG.
Article details
Article ID: 173
Category: EPC Conventions for England & Wales Issue 4
Date added: 22-03-2013 08:36:19
Views: 1709

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