Start with the job: moving water to a tank, or improving pressure at the outlets? Write down the problem and water source before comparing pumps. Similar appearance or horsepower does not establish equivalent performance.
Record the source and pump location
Identify whether the supply comes from an underground or elevated tank, and where the pump sits relative to the water level when the tank is low. These details affect suction requirements. Do not assume every pump is self-priming or suitable outdoors; check the model's operating limits.
Gather the demand information
Note the height of the highest outlet, how many taps or showers may operate together, and the pipe sizes. Ask a specialist to assess the required pressure and pipework losses. Floor count alone does not describe every home, and one running outlet creates a different demand from several.
Compare flow and head together
A pump performance curve relates flow to head. You need suitable performance under your system's conditions, rather than the largest isolated number on the box. Ask the specialist to identify the required duty point and compare it with the pump curve. Horsepower alone is not enough to select the pump.
Check protection and control
Where tank levels vary, ask about dry-running protection and how the model detects an inadequate water supply. Check how the pump starts and stops, and whether the controller is integrated or supplied separately. Float switches, controllers and suction fittings are accessories; confirm that the listing includes a complete pump if that is what you need.
Information to prepare before buying
- Water source and a clear photo of the old pump's label, if available.
- Expected water level, pump location and highest outlet.
- Outlets likely to operate simultaneously.
- Connection sizes and indoor or outdoor location.
- Required flow and pressure assessed by a specialist, plus electrical supply requirements.
Compare models after collecting these details. Check suitability for the water type, operating limits and required accessories. Leave electrical connections, installation and adjustment to a qualified specialist; this is a buying guide, not a wiring procedure.
Related categories: Water Pumps, Float Valves & Accessories.
Technical references
- Grundfos: choosing a booster pump supplied from a storage tank.
- Grundfos: duty point and its relationship to the pump and system curves.
- Grundfos: outlet capacity depends on the model and system conditions.
Grundfos — Selecting a pump for boosting from a storage tank
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