Danfoss MBS 1650 Magnetic Bypass Valve | 1/2" to 1", 0-10 bar, Pressure-Independent Specs

Danfoss MBS 1650 Magnetic Bypass Valve | 1/2" to 1", 0-10 bar, Pressure-Independent Specs

Danfoss MBS 1650 magnetic bypass valve specifications. Pressure-independent bypass, 1/2" to 1" sizes, 0-10 bar, for hydronic heating systems. Protects pumps and maintains Δp.

Product Overview

The Danfoss MBS 1650​ is a pressure-independent magnetic bypass valve​ designed for hydronic heating and cooling systems. This model automatically maintains a constant differential pressure (Δp) across a variable speed pump​ by bypassing excess flow, available in sizes from 1/2" to 1". It operates within a 0-10 bar pressure range​ and features a magnetic pilot system​ for precise control. The "MBS 1650" designation identifies this specific bypass valve designed to protect pumps, prevent noise, and ensure stable system operation in circuits with thermostatic radiator valves (TRVs) or other two-port valves.

Technical Specifications

Note: Specifications are based on Danfoss MBS series documentation. The MBS 1650 typically has a fixed, low Δp setting (e.g., 0.15 bar) suitable for protecting the pump in residential systems. The Kvs is for the bypass path when fully open.

Key Features

• Pressure-Independent Operation:​ Automatically bypasses excess flow to maintain a set differential pressure, stabilizing the pump operating point.

• Pump Protection:​ Prevents the pump from operating against a closed head (dead head) when most zone valves or TRVs are closed, extending pump life and preventing noise.

• Magnetic Pilot System:​ Uses a magnetic cartridge instead of a capillary tube, making it more robust and insensitive to installation orientation.

• Pre-Set Differential Pressure:​ Factory set for typical residential heating systems, simplifying installation (no adjustment required).

• Compact Design:​ Easy to install in the pump bypass line near the hydraulic separator or pump itself.

• Maintenance-Free:​ Sealed magnetic system requires no end-user maintenance.

How It Works

The valve is installed in a bypass line between the supply and return headers. It remains closed under normal system Δp. If the system Δp rises (because downstream valves close), the valve opens to bypass flow, thereby limiting the Δp across the pump to its pre-set value.

Typical Applications

• Residential Heating Systems:​ Installed in the bypass line of systems with a variable speed circulator and multiple thermostatic radiator valves (TRVs).

• Underfloor Heating Manifolds:​ Used as a bypass on mixing unit or manifold to protect the secondary pump.

• Small Commercial HVAC:​ In systems with zone valves to maintain stable pump conditions.

• Any system with a variable speed pump​ and two-port control valves that may cause significant flow variation.

Important Technical Notes

1. Fixed Setting:​ The MBS 1650 typically has a fixed, non-adjustable​ differential pressure setting (e.g., 0.15 bar). For systems requiring a different Δp, other models in the MBS range (e.g., with adjustable settings) must be selected.

2. Correct Sizing:​ Select the valve size (DN15, DN20, DN25) to match the pipe size of the bypass line. Its Kvs should be sufficient to bypass the minimum flow required by the pump at the set Δp.

3. Installation Location:​ Install in the bypass line​ between the supply and return, as close to the pump or hydraulic separator as possible. Follow the flow direction arrow.

4. System Design:​ This valve is not a substitute for a hydraulic separator​ in systems with multiple pumps or significant differential pressures. It is designed for pump protection​ in simpler systems.

5. Orientation:​ Can be mounted in any position, but horizontal is recommended for best performance and to avoid trapping air in the upper chamber.

6. Pipe Preparation:​ Use with clean, deburred copper pipe. Ensure the olive and union nut are properly tightened to prevent leaks.

Note: This data sheet provides general specifications for the Danfoss MBS 1650 bypass valve. For system design guidelines, specific installation diagrams, and compatibility information, consult the official Danfoss MBS Technical Documentation. Confirm the exact pre-set Δp value and Kvs for the specific size with the supplier.