Bosch 940 ES Installation And Operating Instructions Manual page 37

DANGER:
Explosion hazard!
▶ The heater must be isolated from the gas supply piping
system during any pressure testing of that system at test
pressures equal to or more than 0.5 psig. If overpressure
has occurred, such as through improper testing of the gas
lines or malfunction of the supply system, the gas valve
must be checked for safe operation.
GAS CONNECTIONS
▶ Install a manual gas shut off valve on the gas supply line
within easy reach of the appliance.
▶ Install a union when connecting gas supply.
▶ The minimum internal diameter required for any appliance
connector is ¾", see chapter 4.9.1 for more details on pipe
sizing.
▶ Undersized flexible appliance connector not permitted.
▶ National Fuel Gas Code requires that a sediment trap (drip
leg) be installed on gas appliances not so equipped. The
drip leg must be accessible and not subject to freezing
conditions. Install in accordance with the
recommendations of the serving gas supplier, see fig. 2.
Fig. 31 Gas connection
[1] Gas supply
[2] Cap
[3] Minimum 3"
Once connections are made, check for gas leaks at all joints.
Apply some gas leak detection solution to all gas fittings.
Bubbles are a sign of a leak. A combustible gas detector may
also be used to detect for leaks.
940 ES – 6 720 644 930 (2019/09)
DANGER:
Explosion hazard!
▶ If you detect a leak, shut off the gas. Tighten appropriate
fittings to stop leak. Turn the gas on and check again with a
gas leak detection solution. Never test for gas leaks using a
match or flame.
GAS LINE SIZING
The gas supply piping for a single heater should be sized for a
maximum draw of 199,000 BTU/hr. Measure the length of gas
supply line from the building's gas main to the heater and use
the chapter 4.9.1 and 4.9.2, page 38 or the gas line
manufacturer's sizing tables to determine the pipe diameter
necessary. If there are more gas drawing appliances on the line,
size the gas line according to the total maximum amount of BTU
draw input rating of for all appliances combined.
Note: Undersizing the gas line may result in diminished hot
water flow rate and temperature. See chapter 4.14, page 45
for the procedure to measure gas pressure. Proper gas
pressure must be confirmed at time of installation.
Installation instructions
37