Recirculation pump Termojet AUTO energy-saving HBS 24-12

Termojet AUTO HBS 24-12 recirculation pump — a domestic hot water (DHW) recirculation pump operating at a safe voltage of 24V DC. It maintains continuous hot water circulation from the boiler through the return pipes, so when a tap is opened, hot water appears instantly — no waiting, no cold water waste. Connection: 1″ IG thread (internal thread of union nut). Power: 3–55 W, maximum head 12 m, flow rate up to 25 l/min.

Technical Specifications

AUTO Operating Modes

Constant differential pressure (Δp-c). The pump maintains the set pressure difference in the recirculation pipeline regardless of hot water draw-off. The Δp-c mode is optimal where several water draw-off points are connected in parallel.

Proportional differential pressure (Δp-v). The differential pressure decreases proportionally to the reduction in flow — the pump minimises consumption at night or during reduced water draw-off. The Δp-v mode reduces pipe noise and electricity consumption under partial load.

The built-in thermostat automatically switches the pump off when the return pipe temperature reaches 38°C and switches it back on when it cools to 33°C — hot water is always ready without excessive overheating.

Why the HBS 24-12 is a unique solution

Most DHW recirculation pumps operate on 230V AC. The HBS 24-12 runs on a safe 24V DC constant voltage, which provides two fundamental advantages. First, safety in wet areas (bathroom, boiler room): the low voltage eliminates the risk of electric shock in the event of a fault. Second — and this is critical for Ukraine — the pump connects to a standard battery-backed UPS (uninterruptible power supply), meaning DHW recirculation continues to operate even during a power outage. A standard 230V AC pump stops in this situation and the hot water "stagnates" in the pipes.

The maximum head of 12 m allows the pump to serve a recirculation circuit in a two- or three-storey building — most 230V AC equivalents are limited to 1–1.5 m, so the HBS 24-12 covers a significantly wider range of installations.

Applications

• Country house or cottage with an indirect-fired boiler: instant hot water on all floors.
• Apartment with a boiler: recirculation within the bathroom and kitchen.
• Installations without stable 220V power: UPS ensures continuous recirculation.
• Heat pump systems where the boiler is heated by an HP: Termojet heat pumps combined with the HBS 24-12 deliver round-the-clock hot water at minimal cost.

Ideal for heat pump systems

A heat pump heats the boiler to 45–55°C — the ideal range for DHW recirculation. The HBS 24-12 thermostat accurately tracks this range, switching the pump off at 38°C and keeping hot water on standby. Choosing a quiet 24V DC pump for such a system minimises overall consumption. See the full product catalogue at tjheatpump.com.ua.

Frequently Asked Questions

Which UPS should power the HBS 24-12?
Any UPS or charger with a 24V DC output and a current of at least 3 A. Most battery-backed boiler UPS units have such an output — check whether your device has a 24V DC output.

Is a check valve required?
Yes, a check valve is installed at the point where the recirculation return pipe connects to the boiler or at the pump inlet — it prevents cold water from flowing back into the hot supply line.