State Water Heaters SCE 65-400, Installation, User And Service Manual

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Safety of the installation
Release R.1.0 Uk 17
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2.5.2 Vented installation (open)
With a vented installation, excess pressure is taken up by the open water
reservoir. The level of the water reservoir determines the maximum working
pressure in the tank, which may not exceed 8 bar. The installation must also be
fitted with an overflow from the hot water pipe that empties into the water
reservoir. See paragraph
’3.6.3 Hot water side’ .
2.5.3 T&P valve
A T&P valve is only required in 'unvented' installations. State however also
recommends the use of a T&P valve in ‘vented’ installations.
A T&P valve monitors the pressure in the tank and the water temperature at the
top of the tank. If the pressure in the tank becomes too high (>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 averted. The appliance has a connecting point for a
T&P valve as standard. See paragraph
’3.6.3 Hot water side’ .