7
Open Vented Syste s
Please see figure 3 for a gen-
eral layout for an open vented
water heater installation. The
following safety devices must be
fitted to the water heater:
1. Feed and Vent cistern.
2. Ther ostatic control — En-
ergy Cut Out Device
The normal water storage tem-
perature is 60° C. The water
heater thermostat should be
wired to ensure that the energy
supply to the water heater is
interrupted if the water tempera-
ture exceeds 60° C.
The following safety devices
ust be fitted to the water
heater when used in an open syste :
1 Stop Valve: This allows the system to be isolated from the cold water supply.
2 Drain Valve: This allows the water heater to be drained for service or removal.
3 Blending (Mixing) Valve: The blending valve limits the temperature of the delivered water by
mixing it with cold water as required. The delivered water temperature should not exceed
50°C.
Zone Valve: The recommended water storage temperature is 60°C. The water heater ther-
mostat should be wired to ensure that the energy supply to the water heater is interrupted if
the water temperature exceeds 60°C. The zone valve is used for this purpose.
5 Cold Water Cistern: This is the cold water storage cistern. The Vent pipe is also returned to
the cistern.
6 Vent pipe: This is also referred to as the expansion pipe and is used to safely vent expansion
of the heated water.
Failure to fit these essential safety evices will invali ate the warranty an may cause a angerous installation.
WARNING: All water heaters must be fitte with temperature control to ensure that the omestic water
is not heate to excessive temperatures.
A blen ing (mixing) valve must be fitte to all installations to ensure water oes not excee 50°C at the
point of use.
Figure 3 - Open Vented ystem chematic