DomesticWater And Sprinkler Systems

A twin set uses two pumps working together — typically one duty and one standby — to maintain flow and pressure, with the second pump cutting in if the first fails or demand rises. A triple set adds a third pump for additional capacity or redundancy, which is often specified where the sprinkler system needs to guarantee flow even if two pumps are out of action. Which you need depends on the occupancy risk category and flow rate set out in your fire strategy or BS9251:2021 design.

Yes, where the booster set draws from or interfaces with the mains-fed potable supply, WRAS approval is required to prevent contamination risks such as backflow. Our twin and triple booster sets are fully WRAS approved, so they can be connected to the domestic supply without compromising water quality. This is separate from BS9251 compliance, which governs the fire suppression performance of the system.

Tank capacity is driven by the sprinkler design flow rate and the minimum duration required under BS9251:2021, which varies by property risk category — typically 30 minutes for domestic (low hazard) systems. You'll also need to allow for everyday domestic water usage if the tank is shared, rather than dedicated solely to fire protection. We'd recommend confirming the flow and storage figures with your fire engineer or sprinkler designer before selecting a tank, as undersizing is a common and costly mistake.

Yes, combined domestic and sprinkler systems are common and are specifically covered by BS9251:2021, provided the design ensures the sprinkler supply always takes priority and can't be depleted by normal household use. This usually means a dedicated reserve volume within the tank that's protected from domestic draw-off, along with controls that manage both duties. Our booster sets are designed with this dual function in mind, combining everyday pressure boosting with guaranteed fire flow.

Routine checks should cover pump operation, pressure switches, non-return valves and the control panel, along with a periodic test of the automatic changeover between duty and standby pumps. BS9251:2021 recommends regular servicing intervals to keep the system in a state of readiness for both domestic and fire duties. Real-time monitoring on our systems helps flag faults early, but a qualified engineer should still carry out scheduled inspections and testing.

Booster sets are usually installed in a plant room or dedicated enclosure close to the storage tank, with adequate access for maintenance, ventilation and drainage in case of leaks. The tank itself can be sited above or below ground depending on available space, though below-ground tanks need suitable access for desludging and inspection. Electrical supply, alarm signalling and pipework runs should all be planned early, as retrofitting a booster system into a tight plant room is far harder than designing it in from the start.