BS 5918:2015

This British Standard gives recommendations and guidance for the installation of common indirect solar domestic hot water (SDHW) systems for all types of building in the UK. It includes recommendations and guidance for design, handling, installation, commissioning, handover, maintenance, decommissioning and fault-finding.

NOTE 1 SDHW is domestic hot water (DHW) that has intentionally received heat derived from solar radiation via a solar collector.

The standard covers systems:

1. in which solar radiation is converted to heat that is primarily intended for domestic hot water preparation;

2. that contain solar collector(s) intended to transfer heat using an aqueous-based liquid medium;

3. whose solar collectors conform to BS EN 12975‑1 and BS EN ISO 9806;

4. which contain collectors that provide up to 20 kW instantaneous peak power output measured leaving the collector, when tested in accordance with BS EN ISO 9806 at 800 W/m² perpendicular to the collector aperture plane;

   NOTE 2 Depending on the characteristics of the system, this typically equates to a gross collector area of up to approximately 30 m².

5. in which heat is primarily stored in aqueous-based liquid media; and

6. in which the primary circuit is indirect with a heat exchanger that is internal to the solar storage vessel and which separates the primary heat transfer fluid that passes through the collector from the DHW.

This British Standard does not cover:

1. applications that are primarily intended to provide heat for applications such as space heating, cooling or swimming pools and any other than DHW preparation;

2. solar primary system layouts that use solar storage vessels that are outside the building;

3. solar primary system layouts with multiple collector fields;

4. DHW systems that comprise multiple solar or multiple DHW storage vessels; or

5. solar primary system layouts that incorporate a heat pump or other device that utilizes the Carnot cycle.

NOTE 3 It is assumed in the calculations in this British Standard that there is user-disinterest in the DHW settings, i.e. that default factory timer and thermostat settings are present. Extra heating required for bacterial disinfection is not assumed in these calculations.

NOTE 4 Where stated in the standard, the pressure is that exceeding atmospheric pressure at sea level.