Bosch 715ES Reference manual

Models: 715ES, 2400ES, 2700ES
Replacing the Attenuator
Service Bulletin G3-29
Introduction
Bosch Thermotechnology recommends the following water
heater adjustments to accomodate installations with a broader
range of operating conditions and to improve operation with
varying characteristics of LP gas combustion.
Tools needed:
Phillips head screwdriver
Preparation
1. Unplug the water heater power supply cord.
2. Loosen two Phillips head screws located at bottom rear of cover.
(Fig. 1, step 1, pos. 1).
3. Lift front cover upward and remove. (Fig. 1, step 1, pos. 2 & 3)
4. Remove secondary combustion cover by unclipping two upper
and two lower clips securing cover. (Fig. 1, step 2)
Step 1 Step 2
S
tep
1
S
tep
2
Figure 1
3
3
Removing the attenuator
1. Locate attenuator. (Fig. 2, pos. 1).
2. Remove three Phillips head screws from attenuator.
(Fig. 2, pos. 2)
Figure 2
3. Pull attenuator free from heater. Discard the black o-ring
positioned between the fan assembly and attenuator.
(Fig. 3, pos 1.)

Data subject to change without notice | Printed in the USA | 02.2008 Bosch Thermotechnology Corp.
Service bulletin
18 | G3-29 | 715ES, 2400ES, 2700ES
Bosch Thermotechnology Corp.
50 Wentworth Avenue
Londonderry, NH 03053
Tel: [phone]
Fax: [phone]
www.boschpro.com
Fan
Attenuator
Fan
A
ttenuato
r
Figure 3
o-ring
(to be discarded)
Replacing the attenuator
1. Install replacement attenuator to the fan without o-ring.
(Fig. 3, pos. 1).
2. Secure the attenuator to the fan assembly with three Phillips
head screws. (Fig. 2, pos.2).
Adjusting fan speed (LP models only)
Note: Upon replacing the attenuator, if the water heater is a liquid
propane model, the fan speed should be adjusted using the
following the procedure.
1. Plug in power supply cord.
2. Press and hold the program ( ) button while pressing the On/
Off button to the On position. (Fig. 4)
Figure 4
3. Release the program ( ) button when '188' appears on the
display. The display should read 'P2'. If not, repeat process.
(Fig. 4)
4. Press the ( ) button on the control panel until the display reads
'P1'.
5. Press the program ( ) button once and the display should show
the numeric value of the fan speed.
6. Use the ( ) and ( ) buttons on the control unit to select the
new fan speed for your model. The P1 fan speeds should be set
to the following:
Model GWH 2400 ES: P1 fan speed = 37
Models GWH 715 ES and GWH 2700 ES: P1 fan speed = 42
7. Press and hold (± 5 sec.) the program ( ) button until the
display flashes. The selected value is now memorized.
8. Press On/Off button on water heater to Off position. Press On/
Off button again to turn water heater back on.
9. Replace combustion cover only.
Adjusting CO₂
1. The water heater requires a CO₂ adjustment after the installation
of the replacement attenuator. Refer to Service Bulletin G3-12
for detailed instructions on this process.
2. After adjusting CO₂, replace front cover.
3. Press On/Off button on water heater to Off position. Press On/
Off button again to return water heater to normal service.