This document describes the DU146 automatic bypass and differential pressure valve produced by Honeywell AG. The valve is used to maintain constant differential pressure in a heating system, reduce flow noise, and prevent corrosion caused by acid condensation. It also maintains flow over the temperature sensor on the boiler when radiator valves are closed to ensure proper operation of external temperature compensating controls.
The DU146 automatic bypass and differential pressure valve is designed to maintain a constant differential pressure in heating systems, minimise flow noise and help prevent boiler corrosion. It can be installed between flow and return pipework without external controls and is suitable for pumped hot‑water heating systems and gas‑fired circulation heaters.
The manual includes design details, material specifications, functional description, adjustable pressure range, connection sizes (3/4" and 1 1/4"), and installation recommendations such as fitting shut‑off valves on both sides of the valve.
| Operating temperature | max. 110°C (230°F) |
|---|---|
| Operating pressure | max. 3.0 bar (43.5 PS.I.) |
| Differential pressure adjustable range | 0.05…0.5 bar (0.7…7.3 PS.I.) |
| Set differential pressure at manufacture | 0.2 bar (2.9 PS.I.) |
| Connection size | 3/4" and 1 1/4" |