A bypass radiator, which is commonly part of a central heating system with bypass valves, serves primarily to maintain a constant minimum flow rate through the heat exchanger and provide heat dissipation on pump overrun. It's not always a radiator but a valve between flow and return pipes.
Understanding Bypass Radiators and Valves
Instead of asking about a "bypass radiator," it's more accurate to discuss bypass valves in relation to central heating systems, since the actual bypass is usually a valve and pipe setup, not a radiator itself. These valves play a crucial role in system operation.
Key Functions of Bypass Valves
- Maintaining Minimum Flow Rate: Bypass valves ensure that a minimum flow of water always circulates through the boiler's heat exchanger.
- Preventing Overheating: The purpose of the bypass valve is to dissipate extra heat when all or most radiators are turned off or closed with thermostatic radiator valves (TRVs).
- Pump Overrun Protection: After the boiler shuts down, the pump often continues to run for a short period. The bypass valve provides a path for the water to circulate, preventing potential damage from overheating or pressure buildup.
How Bypass Valves Work
A bypass valve is installed between the flow and return pipes of the heating system. When the pressure difference between the flow and return increases (usually because TRVs have closed off radiators), the bypass valve opens. This allows water to flow directly from the flow to the return, maintaining the minimum flow rate through the boiler.
Benefits of Using a Bypass Valve
- Protects the Boiler: Maintains adequate flow through the heat exchanger.
- Extends Boiler Life: Prevents overheating and related stress on components.
- Ensures System Stability: Manages pressure fluctuations.
