Bosch 715ES Reference manual

Models: 715ES, C800ES, C920ES, C920ESC, 2400ES, 2700ES
Measuring and adjusting CO₂
Service Bulletin G3-12
Introduction
NOTE: The CO2levels can only be adjusted by a trained gas
technician with a calibrated combustion gas analyzer. Please
note that a combustion gas analyzer is not the same equipment
as a CO detector.
Tools needed:
Combustion gas analyzer
Flat head screw driver
Phillips head screw driver
#40 Torx driver
Measure gas pressure
One factor that will affect CO2levels is improper gas pressure.
Please see bulletin G3-02 for the procedure to measure gas
pressure. Correct any deciencies in gas pressure before
proceeding.
Preparation
1. Open several hot water taps and let the water heater run for 1-2
minutes. Close hot water taps and return to heater.
2. Push the ON/OFF button to the OFF (O) position.
3. Remove brass at head screw with gasket on the exhaust collar
to reveal measuring port. (Fig. 1)
Figure 1
4. Insert CO2analyzer probe into the measuring port. The tip of the
probe should be in the center of the ue pipe (approx 1.5”
inserted).
5. While pressing the Program ( ) button, press the ON/OFF
switch to ON (I) position. As soon as ‘188’ ashes on the dis-
play, release the program button. The display should now read
P2. (Fig. 2). (Fig. 2)
Figure 2
Measuring CO2
1. Open enough hot water taps to achieve a ow rate of at least 6
gallons per minute. (1 tub and 2 sinks should be sufcient)
2. Press the ( ) button until P1 appears.
3. Record the P1 CO2reading below.
P1 CO2reading: % CO2
4. Press the ( ) button until P2 appears. Unit will ramp down to
low re and the water ow should decrease.
5. Record the P2 CO2 reading below (Analyzer reading may take
several minutes to stabilize).
P2 CO2reading: % CO2
6. Compare your readings to those found in Table 1. If CO2
readings are incorrect, make adjustments as outlined in the next
section.

Data subject to change without notice | Printed in the USA | BTC710002306 A | 01.2009 Bosch Thermotechnology Corp.
Service bulletin
18 | G3-12 | 715ES, C800ES, C920ES, C920ESC, 2400ES, 2700ES
Bosch Thermotechnology Corp.
50 Wentworth Avenue
Londonderry, NH 03053
Tel: [phone]
Fax: [phone]
www.boschhotwater.com
Proper CO2readings Table 1
Natural Gas LP Gas
715ES, 2700ES Max input P1 7.0 - 7.6 % 8.3 - 8.9 %
715ES, 2700ES Min input P2 2.3 - 2.6 % 2.5 - 2.8 %
2400ES Max input P1 6.9 - 7.5 % 8.1 - 8.7 %
2400ES Min input P2 2.3 - 2.6 % 2.5 - 2.8 %
C800ES Max input P1 7.8 - 8.4 % 9.5 - 10.1 %
C800ES Min input P2 1.5 - 1.8 % 1.7 - 2.0 %
C920ES, C920ESC Max input P1 8.3 - 8.9 % 9.9 - 10.5 %
C920ES, C920ESC Min input P2 2.1 - 2.4 % 2.5 - 2.8 %
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 CO2
NOTE: Adjusting P1 CO2levels will change the P2 CO2levels.
Conrm the P1 value BEFORE adjusting the P2 level.
Adjusting P1 CO2level
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 rotateLoosen 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 P1Adjusting the brass slotted screw counter-clockwise will raise P1
CO₂ levels and clockwise will lower P1 CO₂ levels.
(Fig. 3, pos. 2)
Figure 3
Adjusting P2 CO2level
1. Remove yellow painted #40 Torx cover from the front of the gasRemove 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 willAdjusting the plastic �40 Torx screw counter-clockwise will
lower P2 CO₂ levels and clockwise will raise P2 CO₂ levels.
(Fig. 4)
Figure 4
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 rangesVerify that both P1 and P2 readings are within the ranges
specied in Table 1. Continue adjusting the P1 and P2 levels as
necesssary until CO2 values are within the specied ranges.
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 ncoils 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 CO
Max input P1 250ppm
Model C800ES, C920ES, C920ESC
Max input P1 290ppm
Returning to Service
1. Return slotted cover to original position.
2. Reinstall Torx cover.
3. Remove CO2 analyzer probe and reinstall brass athead screw
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.