A.O. Smith ADM - 40, Инструкция по установке, эксплуатации и обслуживанию

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Working principle of the appliance
14 Instruction manual ADM
2
gis
2.5 Safety of the
installation
In addition to the standard safety monitoring of the appliance, the appliance
must also be protected by an expansion vessel, expansion valve, non-return
valve and a T&P valve.
Use of an expansion vessel and expansion valve depends on the type of
installation: unvented or vented.
2.5.1 Unvented installation
With an unvented installation, an expansion valve valve and expansion vessel
prevent the buildup of excessive pressure in the tank. This prevents damage
being caused to the enamelled coating (in the appliance) or to the tank. A non-
return valve prevents excessive pressure buildup in the water supply system.
This valve also prevents water from flowing backwards from the tank into the
cold water supply system. The pressure reducing valve protects the installation
against an excessively high water supply pressure (> 8 bar). These components
are fitted to the cold water pipe (3.6.6 "Water connections, Vented").
2.5.2 Vented installation
With a vented installation, excess pressure is taken up by the open cold water
head tank. The height of the head tank determines the working pressure in the
water heater, which may not exceed 8 bar. The installation must also be fitted
with a vent pipe from the hot water pipe, that opens into the cold water tank.
Ideally, the vent pipe should discharge into a separate tundish/drain or
otherwise to the open cold water head tank. The water heater should also be
fitted on the hot water side with a stop valve (3.6.3 "Hot water side").
2.5.3 T&P valve
A T&P (Temperature and Pressure Relief) valve monitors the pressure in the
tank and the water temperature at the top of the tank. If the pressure in the tank
becomes excessive (> 10 bar) or the water temperature is too high (> 97 °C),
the valve will open. The hot water can now flow out of the tank. Because the
appliance is under water supply pressure, cold water will automatically flow into
the tank. The valve remains open until the unsafe situation has been rectified.
The appliance is fitted standard with a connecting point for a T&P
valve (3.6.3 "Hot water side").