Boilers contain several types of valves, each serving a critical function within your heating and hot water system. The exact location of "the valve" depends on which type of valve you're referring to, as well as the specific make and model of your boiler. However, a key valve on combi boilers, the diverter valve, is often found in a very accessible spot.
The Diverter Valve on Combi Boilers
For combi boilers, a crucial component is the diverter valve. This valve is responsible for directing hot water either to your central heating system or to your domestic hot water taps, ensuring you get heat when you need it and hot water on demand.
- Location: On some combi boilers, especially in older installations or certain designs, this diverter valve may be found as a lever, often conveniently located behind the bath taps. This lever can typically be pulled up or pushed down to control the flow of hot water.
- Function: It intelligently switches between heating your radiators and providing hot water to your faucets.
- Importance: If this vital component is damaged or malfunctions, you may experience significant issues with both your home's heating and hot water supply.
Other Common Boiler Valves and Their Locations
Beyond the diverter valve, boilers incorporate various other valves essential for safe and efficient operation.
1. Isolation Valves (Service Valves)
These are perhaps the most common and visible valves.
- Location: Typically found on the pipework leading into and out of the boiler. There will be one on the main cold water inlet and others on the heating flow and return pipes.
- Function: Allow you to completely shut off the water supply to the boiler without affecting the rest of the property. Essential for maintenance or in case of a leak.
- Appearance: Often ball valves with a small lever handle.
2. Pressure Relief Valve (PRV)
A crucial safety device.
- Location: Usually located on the boiler casing itself, often connected to a discharge pipe that leads outside.
- Function: Automatically releases excess pressure from the heating system if it rises above a safe limit, preventing damage to the boiler or pipes.
- Importance: A faulty or blocked PRV can lead to dangerous pressure build-up.
3. Automatic Air Vent (AAV)
Helps keep your system free of air pockets.
- Location: Typically found at the highest points of the heating system or within the boiler itself, where air naturally collects.
- Function: Automatically releases trapped air from the system, which can otherwise cause noise, cold spots in radiators, and reduced efficiency.
4. Filling Loop Valve
Used to repressurize the system.
- Location: An external flexible hose (the filling loop) with two small isolation valves, one connecting to the main cold water supply and the other to the heating system.
- Function: Allows you to manually top up the pressure in a sealed central heating system when it drops too low.
- Operation: Must be opened temporarily to add water and then closed securely to prevent over-pressurization or contamination of the mains water.
Summary of Boiler Valves
Understanding the different valves and their locations can help with basic troubleshooting and system maintenance.
| Valve Type | Primary Function | Typical Location | Importance |
|---|---|---|---|
| Diverter Valve | Directs hot water to heating or domestic hot water (combi) | On combi boilers, often a lever behind the bath taps or inside boiler casing. | Crucial for hot water and heating distribution in combi systems. |
| Isolation Valves | Shut off water supply to the boiler | On main inlet/outlet pipes to and from the boiler. | Essential for maintenance and emergency shut-off. |
| Pressure Relief Valve (PRV) | Releases excess system pressure | On the boiler casing, with a discharge pipe leading outside. | Critical safety device to prevent over-pressurization. |
| Automatic Air Vent (AAV) | Automatically releases trapped air from the system | High points in the heating system or within the boiler. | Prevents airlocks, improves efficiency, reduces noise. |
| Filling Loop Valve | Manually repressurizes the heating system | Flexible hose with two valves, connecting cold mains to heating return pipe. | Allows users to maintain correct system pressure. |
While the diverter valve on a combi boiler can sometimes be found as an accessible lever, such as one behind the bath taps, many other essential valves are located directly on the boiler unit or integrated into the pipework surrounding it. Knowing where these components are is key to understanding and maintaining your heating system.
