Diverter Valves in Gas Combi Boliers
Most combi gas boilers have a complicated hydraulic circuit with a circulator pump and a diverter valve. There are two types of diverter valves. The first is a mechanically operated valve powered by a motored diverter head (just like a normal y plan system). Either switches to hot water or heating depends on what is being called for. The second one found on the SPA combis is a hydraulic three way valve. These have diaphragms in that are connected to push rods which operate microswitches to fire the boiler up. They work off a pressure differental valve in hot water mode and in heating mode its the pump.
- The valve piston moves inside the 3-way valve cartridge in the axial direction. The piston is operated by the lever arm (shaft), which is operated by the actuator.
- Due to the special principle of the valve, the shaft seal is not dynamically loaded by axial movement but statically loaded by a tilt motion. This prevents deposits at the shaft and extended wear.
- The actuator is usually a hydraulic diaphragmconnected to the HW
supply system. Opening a tap causes a drop in pressure on one side of
the diaphragm, which is pushed by the pressure on the other side,
operating 3-way valve. There are electric diverter valves (e.g.,
Honeywell) but they're far too slow for this application.
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