Cleaning Condensate Trap; Checking The Mixer Diaphragm; Checking The Expansion Vessel; Setting The Boiler Water Pressure - Bosch Greenstar combi 100 p Installation And Service Instructions For Contractors

Residential gas condensing boiler
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14.1.7 Cleaning condensate trap

▶ Remove condensate trap (steps 1 and 2) and check heat exchanger
orifice for clear passage.
1
Fig. 78 Removing the condensate trap
▶ Remove and clean the condensate trap lid.
▶ Check condensate hose and clean if necessary.
▶ Fill the condensate trap with approx. 1 cup (1/4 l) of water and
reinstall it.

14.1.8 Checking the mixer diaphragm

▶ Open the mixer unit.
▶ Carefully remove the diaphragm from the fan air intake and check for
contamination and cracks.
3
Fig. 79 Opening the mixer unit
Greenstar combi 100 p / 151 p
2
6 720 641 933-93.1o
1
2
6 720 641 933-94.1o
▶ Insert the diaphragm into the fan connector.
The diaphragm flaps must open upwards.
▶ Close the mixer unit.

14.1.9 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.

14.1.10 Setting the boiler water pressure

Display on the pressure gauge
14.5 psi (1 bar)
Minimum filling pressure (when system is cold)
14.5 psi to
Optimal filling pressure
21.75 psi (1 bar
to 1.5 bar)
30 psi (2.07 bar) Maximum pressure at maximum heating water
temperature must not be exceeded (safety valve
will spill).
Table 27 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.

14.1.11 Testing system water quality

▶ Take a representative sample of the system water and analyze pH
using a pH meter or pH test strips.
pH-value
7-8.5
4.5-7
Table 28 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 19, 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.

14.1.12 Checking the electrical wiring

▶ Check electrical wiring for mechanical damage and replace defective
cables.
Inspection and maintenance | 53
Water preparation
Not needed
Required
6720872361 (2017/04)

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Greenstar combi 151 pZwb42-3a seriesZwb28-3a series

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