Water supply pipe not big enough or blocked
Type of Building
Higher levels result in the loss of mains pressure. Official Ofwat Regulation minimum pressure: 7m static head.
Insufficient mains pressure
Water companies must maintain the minimum pressure as guided by official Ofwat GSS Regulation 10
Water fitting design
e.g. Thermostatic mixing valves (TMVs) needing a high flow/pressure to operate, contemporary sanitary appliances requiring higher operating pressures
Determining existing standing pressure – Published guidance: BS EN806 (part 3) / complimentary guide is BS8558. BS6700 is superseded but still cited in Building Regulations. Other guides are available from alternative sources including the Institute of Plumbing.
Measured on an existing property and from local water supply company for a new build. Consideration should also be allowed on oversized pipework, this could still result in multiple draw-off flow/pressure loss.
Flow requirement calculations:
- Total flow rate: Sum of all draw-off flow rates of water appliances.
- Design flow rate: Flow rate for hydraulic calcs, taking into account the probable simultaneous demand.
Pressure requirement calculations:Static head + Pipework friction loss + Discharge pressure required = Pressure requirement (Normally measured in bar).
- Static Head: The physical height difference between the water source and the highest point of use on the system. If the water source is higher than the outlet then the static head pressure is negative.
- Static Head + Friction Loss: Calculated by taking into account: maximum flows / pipework diameters / pipework materials / quantity and type of fittings / equipment in line.
- Static Head + Friction Loss + Discharge Pressure: The pressure is required at the point of use – determined by the equipment to be installed and the level of performance required / normally between 2.0 and 4.0 bar.
Pump system selection will be dependent on the pump function configurations.
There are always pitfalls to every type of booster set, discussing your requirements with the manufacturer is highly advised and recommendations can be made. These may include:
- Adding water conditioners
- Set-up and operation tips
- Design and installation tips
- Single points of failure
- Pump-set considerations (WRAS Approval)
- All pumps to run on major demand
- Closed valve pressure
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