Bosch Tronic TR4500T 50 EB Installation Manual page 12

Installation
safety valve outlet must be piped down vertically and placed in
an environment that is free from the onset of freezing
conditions.
To avoid water dripping from the safety valve, an expansion
tank should be installed on the inlet pipe of the heater with the
capacity of at least 5% of the heater volume.
To ensure proper operation of the safety valve, periodical
inspections must be carried out to remove limescale and make
sure the safety valve is not blocked. To check the valve, open
the outlet of the safety valve by turning the handle or
unscrewing the nut of the valve (depending on the type of the
valve). The valve is operating properly if the water comes out of
the nozzle when the outlet is open.
An open-circuit, non-pressurised system (Fig. 9) requires the
installation of a non-return valve at the water inlet to prevent
water draining out from the tank in the event of the water
supply running dry. This installation mode requires the use of
an instantaneous mixing tap.
As the heating of water expands its volume, this causes the tap
to drip. The dripping cannot be stopped by tightening it further;
on the contrary, the tightening can only damage the tap.
▶ Use the appropriate connection accessories to do the
hydraulic connection to the appliance.
Fig. 8 Closed (pressure) system
[1] Pressure mixer taps
[2] Expansion tank
[3] Safety valve
[a] Test valve
[b] Non-return valve
[4] Funnel with outlet connection
[5] Checking fitting
[6] Pressure reduction valve
[7] Test valve
[H] Cold water
[T] Hot water
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Fig. 9 Open (non-pressure) system
[7] Test valve
[8] Non-return valve
[9] Low pressure mixer tap
[H] Cold water
[T] Hot water
No closing valve may be built-in between the
water heater and return safety valve,
because with it the pressure protection
would be impeded!
The heater can be connected to the domestic water supply
network without a pressure-reducing valve if the pressure in
the network is lower than the nominal pressure. If the pressure
in the network exceeds the nominal pressure, a pressure-
reducing valve must be installed.
In the case of freezing:
▶ Switch off the appliance.
▶ Purge the appliance ( Chapter 6.5).
Safety valve
DANGER:
▶ Install a safety valve at the water inlet of
the appliance (Fig. 8).
NOTICE:
NEVER OBSTRUCT THE PURGE OUTLET OF
THE SAFETY VALVE.
Never install any accessory between the
safety valve and the cold-water inlet (right
hands side) of the appliance.
Tronic – 6 720 884 457 (2018/02)