Bosch AQ250SX, Сборник сервисных бюллетеней

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Data subject to change without notice | Printed in the USA | 03.2007 Bosch Water Heating
BBT North America Corporation
Bosch Group
Bosch Water Heating
340 Mad River Park
Waits
fi eld, VT 05673
Telephone 800-642-3111
Fax (802) 496-6924
techsupport@boschhotwater.com
Service bulletin
18 | TWH-G2-12 | 2400E, 2400EO, 250SX, 250SXO, 635ES, 635ESO
Adjusting CO
2
NOTE: When making adjustments with the front cover off, CO
2
levels
will be 0.3 - 0.5 % lower than with the front cover on. Make fi nal
readings with the front cover installed.
NOTE: Adjusting P1 CO
2
levels will change the P2 CO
2
levels. Con-
fi rm the P1 value BEFORE adjusting the P2 level.
Adjusting P1 CO
2
level
1. Loosen yellow painted Philips screw and cover should rotate
down revealing a brass slotted screw.
Adjusting P1 CO
2
level
2. Adjusting the brass slotted screw counter-clockwise will raise P1
CO2 levels and clockwise will lower P1 CO2 levels.
Adjusting P2 CO
2
level
1. Remove yellow painted #40 Torx cover from the front of the gas
valve. A plastic #40 Torx screw will be revealed.
Adjusting P2 CO
2
level
2. Adjusting the plastic #40 Torx screw counter-clockwise will
lower P2 CO2 levels and clockwise will raise P2 CO2 levels.
NOTE: These screw adjustments are very sensitive and may take
several minutes to stabilize.
Final readings
1. Verify both P1 and P2 are within the ranges speci fi ed in the
table below. Continue adjusting the P1 and P2 levels as necess-
sary until CO
2
values are within the speci fi ed ranges.
Proper CO
2
readings
Natural Gas LP Gas
Max input P1 9.7 ±
0.3 %
10.7 ± 0.3 %
Min input P2 9.5 ±
0.5 %
10.5 ± 0.5 %
2. As a safety precaution, verify the Carbon Monoxide (CO) read-
ings on P1. CO levels should not exceed 300ppm (follow local
codes if more restrictive). If values exceed this limit, inspect
vent system and
fi ncoils on the heat exchanger for blockage. To
access heat exchanger fi ncoil, refer to service bulletin TWH-G2-
22.
Proper CO readings
Natural Gas LP Gas
Max input P1 300ppm 300ppm
Returning to Service
1. Return slotted cover to original position.
2. Reinstall Torx cover.
3. Remove CO
2
analyzer probe and reinstall brass fl athead screw in
exhaust collar.
4. Turn ON/OFF switch to the OFF (O) position and then back to
the ON (I)position.
5. Heater is ready for normal operation.