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Gas Piping & Connections - Bosch Greentherm 9800 SE 160/199 Manual

Indoor residential and comme rcial tankless water heaters
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28 | Installation instructions
Gas piping & connections
Before connecting the gas supply, be sure that the heater is set
for the same gas to which it will be connected.
In the United States: The installation must conform with local
codes or, in the absence of local codes, the National Fuel Gas
Code ANSI Z223.1/NFPA 54.
In Canada: The Installation must conform to CGA B149
INSTALLATION CODES and/or local installation codes.
DANGER: Explosion hazard!
▶ DO NOT connect to an unregulated or
high pressure propane line or to a high
pressure commercial natural gas line.
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.
▶ Install a manual gas shut off valve on the gas supply line
within easy reach of the appliance.
▶ Install a union when connecting the gas supply.
▶ Gas connection to the water heater is ¾ " NPT. See chapter
4.8.1 for the minimum internal pipe diameter required.
▶ Undersized flexible appliance connector is 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. 20.
6 720 816 815 (2016/10)
Fig. 20
Gas connection
[1] Shut off valve
[2] Gas supply
[3] Cap
[LA] Minimum 3" sediment trap, (drip leg)
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.
DANGER: Explosion hazard!
▶ If you detect a leak to the room, shut off
the gas and allow for space aeration
(open windows, doors). 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.
The gas supply piping for a single heater should be sized for a
maximum draw of 199000 BTU/hr for Greentherm 9800 SE /
SEC 199. Measure the length of the gas supply line from the
building's gas main to the heater and use the chapter 4.8.1 and
4.8.2 or the gas line manufacturer's sizing tables to determine
the pipe diameter necessary. If there are more gas appliances
on the line, size the gas line according to the total maximum
amount of BTU draw input rating of for all appliances
Note: Undersizing the gas line may result in diminished hot
water flow rate and temperature, or improper appliance
operation (noise and combustion instabilities). See chapter
4.13, page 36 for the procedure to measure gas pressure.
Proper gas pressure must be confirmed at time of installation.
Greentherm 9800 SE 160/199 | SEC 199



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