Honeywell Home DU145 22mm Angled Automatic Bypass Valve

The Honeywell Home DU145-3/4B Automatic Bypass Valve is designed to maintain correct water circulation within central heating systems.

Installed between the flow and return pipework, the valve opens automatically when required. This helps protect the boiler, maintain minimum flow and improve overall heating system efficiency.

The valve responds to changes in system pressure caused by closing thermostatic radiator valves or motorised zone valves. By maintaining circulation through the boiler, it can help prevent overheating, reduce system stress and extend the life of heating components.

Its 22mm compression fittings allow straightforward installation, while the adjustable differential pressure range of 0.1 to 0.6 bar supports accurate system setup. The valve can handle flow rates of up to 50 litres per minute.

A lockable pressure adjustment mechanism helps prevent accidental changes after the system has been commissioned.

Technical Specifications

Brand: Honeywell Home
Model: DU145-3/4B
Manufacturer Part Number: DU145-3/4B
Product Type: Automatic Bypass Valve
Connection Size: 22mm compression
Flow Capacity: Up to 50 litres per minute
Pressure Adjustment Range: 0.1–0.6 bar
Configuration: Angled
Warranty: 1 year

Suitable Applications

• Domestic central heating systems
• Combi boiler installations
• Zoned heating systems
• Systems with thermostatic radiator valves
• Systems with motorised zone valves

Benefits of an Automatic Bypass Valve

The Honeywell DU145-3/4B helps protect the boiler when heating circuits close and maintains the minimum circulation required for safe operation.

It can also reduce water-flow noise, improve system efficiency and support stable operating conditions throughout the heating system.

Why Choose the Honeywell DU145-3/4B?

Honeywell Home is a trusted manufacturer of heating controls and system components.

The DU145-3/4B offers dependable flow protection, simple commissioning and long-term performance. Its adjustable pressure control and lockable setting make it a practical choice for professional heating installations.

Delivery and Collection

This product can be collected from our showroom at:

Unit 5, Penn Street
Newcastle upon Tyne
NE4 7BG

Most collection orders are prepared on the same day. Select the collection option at checkout, and the product will be prepared for you.

Fast UK delivery is also available through Royal Mail First Class, with most orders arriving within 1–2 working days. Each item is securely packaged to help prevent damage during transit.

Always use a suitably qualified engineer for installation. Any work involving gas appliances should be completed by a Gas Safe registered engineer.

Honeywell DU145-3/4B Automatic Bypass Valve

• Maintains consistent water flow through the boiler
• Helps reduce system noise and pressure fluctuations
• Adjustable pressure range from 0.1 to 0.6 bar
• Features 22mm compression fittings for straightforward installation