Bosch Installation Manual

Inspection and maintenance
Greenstar – 6721822579 (2021/01)
70
15.1.9 Checking the expansion vessel
Annual inspection of the expansion vessel is required.
▶ Depressurize the appliance.
▶ If necessary, adjust the expansion vessel pre-charge pressure to the
static head of the heating system.
15.1.10 Setting the boiler water pressure
Table 31 Operating pressure
▶ If the indicator is below 14.5 psi (1 bar) when the system is cold, top
up the water. The indicator must be between 14.5 psi (1 bar) and
21.75 psi (1.5 bar).
If using a hose to fill the heating system, prefill the hose with water to
prevent air being introduced into the system.
▶ If the pressure is not held, check the expansion vessel and heating
system for leaks.
15.1.11 Testing system water quality
▶ Take a representative sample of the system water and analyze pH
using a pH meter or pH test strips.
Table 32 Water preparation for filling and maintaining the heating system
(pH-value)
▶ If the value is outside of the permitted range, drain the system, flush,
and refill with fresh water to prevent system damage or leaks.
▶ If the fill water does not meet the requirements of page 29, treat the
water to bring it within the permissible range.
▶ If antifreeze is being used in the system, check the frost protection
properties to ensure the site specific requirements are met.
15.1.12 Checking the electrical wiring
▶ Check electrical wiring for mechanical damage and replace defective
cables.
Display on the pressure gauge
14.5 psi (1 bar) Minimum filling pressure (when system is cold)
14.5 psi to
21.75 psi (1 bar
to 1.5 bar)
Optimal filling pressure
30 psi (2.07 bar) Maximum pressure at maximum heating water
temperature must not be exceeded (safety valve
will spill).
pH-value Water preparation
7-8.5 Not needed
4.5-7 Required