In a building with long hot water pipes, the water in the pipe cools while nobody's using it. Open a tap at the far end and you run cold water down the drain until the hot arrives. A hot water circulation system fixes that with a ring main: a loop from the heater, past the outlets and back again, with a small circulation pump keeping the water moving so it's hot all the way round.
The circulation pumps PSA stocks split into single circulators and pre-plumbed dual pump systems.
Single circulators
- Hyjet HPD: stainless steel casing, ceramic shaft and bearings, polypropylene composite impeller, EPDM seals, 110°C and 10 bar maximum, IP44 Class F motor with built-in capacitor and thermal protection, 3-speed manual adjustment and couplings included. Listed for domestic and commercial hot water and chilled water circuits. Sizes: HPD20-60 (20mm, 100W, $523.55), HPD25-60 (25mm, 100W, $639.05) and HPD32-80 (32mm, 245W, $1,013.05).
- Bromic 3-speed circulation pump (7575250, $350.85): stainless body and unions, 100W/70W/55W speeds, 50 L/min max flow, 6m max head, 2–110°C water, 3/4 inch G connections at 130mm port spacing, with stainless adaptors for retrofitting. Stock is limited, so contact PSA to confirm availability.
A single circulator suits a house or small building where a short outage while the pump is replaced is acceptable. Use the speed setting to match the flow the ring main needs; running faster than needed wastes power and can cause noise and erosion in copper pipe.
Dual circulator systems
The Hyjet DHWC is a pre-plumbed dual system with two HPD circulators, stainless 304 manifolds, dual check valves and ball valves, all mounted on a galvanised back plate. Two pumps give a backup if one fails, which matters in hotels, aged care, hospitals, apartments and commercial buildings where hot water can't simply stop.
| System | Pumps | Manifolds | Standard controller | Deluxe controller |
|---|---|---|---|---|
| DHWC2060 | 2 x HPD20-60 | 25mm | $4,269.05 | $5,209.55 |
| DHWC2560 | 2 x HPD25-60 | 25mm | $4,472.55 | $5,418.55 |
| DHWC3280 | 2 x HPD32-80 | 32mm | $5,891.55 | $7,008.05 |
Standard or deluxe controller
- Standard: a weatherproof polycarbonate controller with a Pump 1 / Auto / Pump 2 switch and an in-built timer.
- Deluxe: a powder-coated metal controller with a lockable isolator, LED indicators, a 12-hour timer, a thermostat input and a BMS output, so the building management system can see and control the pumps.
The deluxe adds between $940.50 and $1,116.50. It's worth it in any building with a BMS, or where the pumps should only run when the return water temperature drops.
Designing it
- Flow and head. The circulator only has to overcome friction around the loop, not lift water, so it's usually a small pump. Size it from the ring main's length, pipe size and the flow needed to keep the far end hot, and check against the pump curve in the datasheet.
- Return line and balancing. Branches on a large system need balancing valves so the water doesn't take the shortest route and leave the far end cold.
- Insulate the loop. An uninsulated ring main loses a lot of heat. Insulation is what makes circulation efficient.
- Compliance. Heated water circulating systems must be designed and installed to AS/NZS 3500.4, including its requirements for water temperature and tempering at outlets used for personal hygiene. Installation by licensed plumbing and electrical trades.
For a dual pump controller to run your own pumps, see the HydroSTART hot water controller. If the problem is low hot water pressure rather than slow hot water, see our guide to hot water booster pumps. The Hyjet range is available to order on backorder; contact PSA to confirm lead time.
Frequently Asked Questions
What does a hot water circulation pump do?
It keeps hot water moving around a ring main from the heater, past the outlets and back, so hot water reaches the tap straight away instead of after a long run of cold water.
Do I need one or two circulation pumps?
One suits a house or small building. Two, as in the Hyjet DHWC system, give a backup pump for hotels, aged care, apartments and commercial buildings where hot water can't stop.
What does the deluxe DHWC controller add?
A metal enclosure with a lockable isolator, LED indicators, a 12-hour timer, a thermostat input and a BMS output. It costs $940.50 to $1,116.50 more than the standard controller.
Which standard covers hot water circulation systems?
AS/NZS 3500.4, which covers heated water services, including temperature requirements and tempering at personal hygiene outlets.