An automatic bypass valve is fitted inside most combi boilers by the manufacturer these days.
Combi boiler central heating system diagram.
How a combi boiler works at least a modern combi boiler is.
A combination or combi boiler is both a high efficiency water heater and a central heating boiler in a single compact unit.
In direct contrast open vent also called regular standard or conventional boilers and system boilers heat water that s stored in a tank.
So if it is lashings of hot water at a forceful pressure you are looking for then this is the system for you.
Central heating system diagram with high pressure boiler this type of system operates at mains water pressure and uses a stored hot water system.
For domestic hot water the mains supply is fed direct to the boiler.
The central heating portion of a combi is on a pressurised closed loop system heated by the boiler as required.
No external pump no tanks no external expansion vessel no motorised valves and in many cases item 6 is not needed either.
A primary heat exchanger.
This diagram illustrates how simple the heating system connected to a combi boiler is.
Secondary plate heat exchanger.
Combi boilers heat water directly from the mains when you turn on a tap so you won t need a hot water storage cylinder or a cold water storage tank in the roof space.
For central heating 2.
They have two heat exchangers inside them.