Hot Water Circulation Pumps: How They Work, Where You Need One and How to Size It
- Return loop to the heater
- Hot water in seconds
- Timer saves energy
- Insulate the pipes
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Why Do Taps Run Cold First?
Hot water sitting in a long pipe cools down. When you open a far tap, you first get all that cooled water, sometimes for a minute or more. That wastes water and time, and in hotels and hospitals it annoys guests and staff. A circulation pump keeps hot water moving so it is always near the tap.
Pumps at H-TECH
GRUNDFOS CIRCULATOR PUMP ALPHA 2KSh 52,000
GRUNDFOS SCALA 2 PUMPKSh 73,000
GRUNDFOS SHOWER BOOSTER PUMP STR2 1.5BARKSh 76,000
GRUNDFOS SHOWER BOOSTER PUMP STR2 2.0BARKSh 84,000| Product | Price |
|---|---|
| GRUNDFOS CIRCULATOR PUMP ALPHA 2 | KSh 52,000 |
| GRUNDFOS SCALA 2 PUMP | KSh 73,000 |
| GRUNDFOS SHOWER BOOSTER PUMP STR2 1.5BAR | KSh 76,000 |
| GRUNDFOS SHOWER BOOSTER PUMP STR2 2.0BAR | KSh 84,000 |
Current listed prices incl. VAT (updated 19 October 2026).
How a Circulation Loop Works
- Hot water leaves the heater or solar tank in the supply pipe to the taps.
- A return pipe runs from the furthest tap back to the heater.
- The circulator, usually on the return pipe near the heater, moves a small, gentle flow round the loop.
- A non-return valve prevents back-flow; a timer or thermostat limits running time.
Circulator vs Booster Pump
| Circulator | Booster pump | |
|---|---|---|
| Purpose | Keeps hot water moving in a loop | Raises pressure at the taps |
| Flow | Small, continuous or timed | Full flow when taps open |
| Use | Long hot pipes, solar systems | Weak showers (see shower booster pumps) |
Sizing and Choosing
- Houses and small hotels usually need only a small domestic circulator; the flow needed is low.
- Choose a model rated for hot water (temperature) and your system pressure.
- Variable-speed or auto-adapt circulators use less power.
- For large buildings, a plumbing engineer sizes the loop and pump to pipe lengths and heat losses.
Saving Energy
- Insulate supply and return pipes; otherwise the loop wastes heat.
- Use a timer for morning and evening peaks in homes.
- With solar heaters, circulate only when the tank is hot enough.
Installation Notes
Install isolation valves either side of the pump so it can be serviced, a non-return valve, and mount the pump with the motor shaft horizontal unless the maker says otherwise. Bleed air from the loop at start-up.
Safety: electrical connections must be made by a qualified electrician, with correct earthing and a breaker sized for the equipment.
Frequently asked questions
What does a hot water circulation pump do?
It keeps hot water moving in a loop so it reaches far taps quickly.
Where is the circulation pump installed?
Usually on the return pipe near the water heater or solar tank.
Does a circulation pump waste electricity?
It uses little power, especially with a timer and insulated pipes.
Is a circulator the same as a booster pump?
No. A circulator moves water round a loop; a booster raises pressure at the taps.
Do I need a return pipe?
Yes, a circulation system needs a return pipe back to the heater.