Bosch 715ES Service Bulletin

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Service Bulletin G3-28
Models: 715ES, C800ES, C920ES, C920ESC, 2400ES, 2700ES
Replacing gas valve
Introduction
This procedure must be performed by a licensed gas technician

with a calibrated combustion gas analyzer.
The gas valve is not gas type specific but requires different CO₂

values when calibrating for different gas types.
Tools needed:
Phillips head screwdriver

Small flat head screwdriver

#40 Torx driver

Combustion gas analyzer

30mm open end wrench or large adjustable wrench

4mm allen wrench

Preparation
1. Unplug water heater and turn off gas to heater using installer
supplied manual shut off valve.
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)
Step 1 Step 1
3
Step 2 Step 2
3
4. Remove combustion cover by unclipping two upper and two
lower clips securing cover. (Fig. 1, step 2)
5. Remove 3 Phillips screws on control unit (Fig. 2, step 1). Place
control unit into the service postion by engaging its tabs with
the holes in the horizontal sheet metal on bottom of the heater
chassis . (Fig. 2, step 2).
Figure 1
Removing the gas valve
1. Unplug wire connection from gas valve. (Fig. 3, pos. 1).
2. Disconnect clear silicone pressure balance tube from right side
of gas valve. (Fig. 3, pos. 2)
3. Loosen and disconnect large 30mm hex nut on the left side of
gas valve. (Fig. 3, pos. 3).
4. Unscrew the three 4mm allen screws from the top of the gas
valve. (Fig. 3, pos. 4).
5. Remove gas valve from the water heater.
Figure 2
Step 1 Step 1
Gas
Valve
Step 2 Step 2