Bosch 715ES Service Bulletin page 2

18 | G3-12 | 715ES, C800ES, C920ES, C920ESC, 2400ES, 2700ES
Proper CO readings
2
715ES, 2700ES Max input P1
715ES, 2700ES Min input P2
2400ES Max input P1
2400ES Min input P2
C800ES Max input P1
C800ES Min input P2
C920ES, C920ESC Max input P1
C920ES, C920ESC Min input P2
NOTE: Values above are for climate controlled conditions. Inputs
such as gas pressure, heating value of the gas, humidity and
temperature of combustion air all impact CO and CO₂ values.
Changes in these inputs can result in different CO and CO₂
values on the same appliance.
Adjusting CO
2
NOTE: Adjusting P1 CO levels will change the P2 CO
2
Confirm the P1 value BEFORE adjusting the P2 level.
Adjusting P1 CO level
2
1. Remove front cover per installation manual to access adjustment
screws. It is critical that the secondary combustion cover
remain on.
2. Loosen yellow painted Phillips screw and cover should rotate Loosen yellow painted Phillips screw and cover should rotate
down revealing a brass slotted screw. (Fig. 3, pos. 1)
3. Adjusting the brass slotted screw counter-clockwise will raise P1 Adjusting the brass slotted screw counter-clockwise will raise P1
CO₂ levels and clockwise will lower P1 CO₂ levels.
(Fig. 3, pos. 2)
Adjusting P2 CO level
2
1. Remove yellow painted #40 Torx cover from the front of the gas Remove yellow painted #40 Torx cover from the front of the gas
valve. A plastic #40 Torx screw will be revealed. (Fig. 4)
2. Adjusting the plastic �40 Torx screw counter-clockwise will Adjusting the plastic �40 Torx screw counter-clockwise will
lower P2 CO₂ levels and clockwise will raise P2 CO₂ levels.
(Fig. 4)
Data subject to change without notice | Printed in the USA | BTC710002306 A | 01.2009
Table 1
Natural Gas LP Gas
7.0 - 7.6 % 8.3 - 8.9 %
2.3 - 2.6 % 2.5 - 2.8 %
6.9 - 7.5 %
8.1 - 8.7 %
2.3 - 2.6 %
2.5 - 2.8 %
7.8 - 8.4 %
9.5 - 10.1 %
1.5 - 1.8 %
1.7 - 2.0 %
8.3 - 8.9 %
9.9 - 10.5 %
2.1 - 2.4 %
2.5 - 2.8 %
levels.
2
Figure 3
NOTE: These screw adjustments are very sensitive and should never
require more than a ¼ turn adjustment. Readings may take 1 or
2 minutes to stabilize.
Final readings
1. Verify that both P1 and P2 readings are within the ranges Verify that both P1 and P2 readings are within the ranges
specified in Table 1. Continue adjusting the P1 and P2 levels as
necesssary until CO values are within the specified ranges.
2
2. As a safety precaution, measure the Carbon Monoxide (CO)
readings in P1. CO levels should not exceed values in Table 2
(follow local codes if more restrictive). If values exceed this
limit, inspect vent system and fincoils on the heat exchanger for
blockage. To access heat exchanger, see service bulletin G3-22
and G3-21 (for C800ES, C920ES, C920ESC models only).
Maximum CO readings
Models 2400ES, 2700ES, 715ES
Max input P1
Model C800ES, C920ES, C920ESC
Max input P1
Returning to Service
1. Return slotted cover to original position.
2. Reinstall Torx cover.
3. Remove CO analyzer probe and reinstall brass flathead screw
2
with gasket in exhaust collar.
4. Press ON/OFF button to the OFF (O) position and then back to
the ON (I)position.
5. Replace front cover. Heater is ready for normal operation.
Service bulletin
Figure 4
Max CO
250ppm
290ppm
Bosch Thermotechnology Corp.
50 Wentworth Avenue
Londonderry, NH 03053
Tel: 1-866-642-3198
Fax: 1-603-584-1681
www.boschhotwater.com
Bosch Thermotechnology Corp.