2 | Operation of the device |
2.5Safety of the installation Apart from the standard security of the device, the installation shall further be protected using an expansion vessel, an expansion valve, a pressure reducing valve, a
The use of an expansion vessel, expansion valve and/or pressure reducing valve is dependent on the type of installation: unvented or vented.
2.5.1Unvented installation
With an unvented installation an expansion valve and an expansion vessel avoid a too high pressure in the tank. This prevents damage to the tank.
A
2.5.2Vented installation
With a vented installation the open water tank absorbs the overpressure. The height of the water tank determines the maximum operating pressure in the tank. The maximum operating pressure is 8 bars. The installation shall also be equipped with an expansion valve of the hot water piping that flows out into the water tank. In the ideal situation this should flow out in a separate discharge channel, otherwise in the open water tank. The device shall also have a stop valve on the water side (3.6.2 “Hot water side”).
2.5.3T&P valve
A T&P valve is only obligatory with unvented installations. However, A.O. Smith recommends using a T&P valve with vented installations as well. A T&P valve (Temperature & Pressure valve) monitors the pressure in the tank and the water temperature at the upper part of the tank. The valve will open when the pressure in the tank becomes too high (> 10 bars) or when the water temperature gets too high (> 97°C). The hot water can now flow out of the tank. As the device is under water piping pressure, cold water will automatically flow into the tank. The valve remains open until the unsafe situation has been removed. The device typically has a connecting point for a T&P valve (3.6.2 “Hot water side”).
14 | Instruction manual TWI |
