Bosch Therm C 1210 ES Installation And Operating Instructions Manual page 36

Installation instructions
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.
WARNING:
▶ If you have 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 225,000 BTUH. Measure the length of gas
supply line from the building's gas main to the heater and use
the chapter 4.8.1 and 4.8.2, page 37 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 44
for the procedure to measure gas pressure. Proper gas
pressure must be confirmed at time of installation.
Fig. 30
[1] Inlet gas particle screen (included)
[2] Gas piping
36 C 1210ES/ESC – 6 720 644 887 (2022/04)