Description

Honeywell DU 145 Angled Automatic Bypass Valve

The Honeywell Home 22mm Angled Automatic Bypass Valve DU145-3/4B is designed to maintain correct water circulation within central heating systems. Installed between the flow and return pipework, this automatic bypass valve opens only when required, helping protect the boiler while improving overall system efficiency.

The Honeywell DU145-3/4B automatically responds to changes in system pressure caused by closing thermostatic radiator valves or motorised zone valves. By maintaining a minimum flow rate through the boiler, it helps prevent overheating, reduces system stress, and extends component life.

Featuring 22mm compression fittings for easy installation, the valve offers a wide adjustable differential pressure range from 0.1 to 0.6 bar and can handle flow rates of up to 50 litres per minute. The lockable pressure adjustment mechanism prevents accidental changes once the system has been commissioned.

Recommended as best practice within UK central heating system specifications, this valve helps improve comfort, reduce noise, and maintain stable operating conditions.

Technical Specifications

Brand: Honeywell Home
Model: DU145-3/4B
MPN: DU145-3/4B
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

Applications

Domestic central heating systems
Combi boiler installations
Zoned heating systems
Systems with thermostatic radiator valves (TRVs)
Systems with motorised zone valves

Benefits of an Automatic Bypass Valve

Protects the boiler when heating circuits close
Maintains minimum circulation requirements
Reduces water velocity noise
Improves overall system efficiency
Helps comply with modern heating system recommendations

Why Choose Honeywell DU145-3/4B?

Honeywell is one of the most trusted names in heating controls. The DU145-3/4B Automatic Bypass Valve provides reliable flow protection, easy commissioning, and long-term performance, making it a preferred choice for heating engineers throughout the UK.

Delivery & Collection

You can collect this product directly from our showroom at Unit 5, Penn Street, Newcastle upon Tyne, NE4 7BG. Most orders are ready the same day, and our team ensures your collection is quick and straightforward. Simply choose the collection option at checkout, and we will prepare your order promptly.

We also offer fast UK delivery through Royal Mail First Class, with most products arriving within 1–2 working days. Each item is securely packaged to prevent damage during transport. For safety, ensure all gas fittings are installed by a qualified Gas Safe engineer.

FAQs

Q: What does an automatic bypass valve do?

It maintains water circulation through the boiler when heating circuits begin to close.

Q: Why is an automatic bypass valve important?

It protects the boiler, reduces system noise, and helps maintain stable system pressure.

Q: What size connections does this valve use?

The valve features 22mm compression fittings.

Q: Can the bypass pressure be adjusted?

Yes, it can be adjusted between 0.1 and 0.6 bar and locked once set.