Navien NCB-20LHWE, Installation & Operation Manual

Page: 26 / 80

5.1 Gas Pipe Material
WARNING
The boiler must be left running for 10 minutes before
checking the gas pressure, to obtain thermal equilibrium.
The gas installation pipes must be made of suitable materials
and comply with the applicable legislation to this respect.
The gas connection must be made using a rigid pipe, inserting a
shut-off valve between the boiler and the pressure regulator.
All the pipes must be suitably fixed in place.
5.2 Propane Gas Installations (LPG)
DANGER
Thoroughly check the seal and the drainage of the entire
installation, as a gas leak could cause serious damage.
If a propane-fired boiler is installed in an interior room
or compartment underground, one side of the building
must be open to the exterior.
If a gas tank is used, it must be installed in a cool,
shaded place away from direct sunlight. It must also
be thoroughly secured to prevent it from tipping over,
which could cause an explosion.
If the boiler is used with propane, a gas regulator suitable for this
type of gas must be installed. The connection and installation
must be made in accordance with the applicable regulations
and standards at the time of installation.
Note
The output pressure of the pressure regulator must be
in accordance with Standard EN 437.
5.3 Measuring the Inlet Gas Pressure
WARNING
The boiler cannot function properly without sufficient inlet
gas pressure. Measuring the inlet gas pressure should be
performed by a licensed professional only.
The inlet gas pressure must be maintained between 17 mbar
and 25 mbar for natural gas and between 25 mbar and 35 mbar
for liquefied propane.
To measure the inlet gas pressure:
1. Shut off the manual gas valve on the gas supply line.
Gas Valve
Opened Closed
2. Open a hot water faucet. The boiler should turn on and the
gas in the gas supply line will be purged.
5. Loosen the screws indicated in the figure below and
connect a manometer to the pressure port. Reset the
manometer to zero before use.
Digital pressure
manometer
6. Re-open the manual gas valve and check for leaks.
7. Open multiple fixtures that have high flow rates, such as
bathtub and shower faucets, to ramp the boiler up to its
maximum firing rate.
8. When the boiler reaches its maximum firing rate, check
the inlet gas pressure reading on the manometer. The gas
pressure must fall within the ranges specified on page 8.
3. Leave the faucet on until the boiler shuts down due to a lack
of gas supply, and then turn off the hot water faucet.
4. Remove the front cover by loosening the 4 Phillips head
screws securing it to the case.
CAUTION
Ensure that no cables are in the way before folding down
the PCB assembly. If the assembly is stuck, do not force
it. Doing so may damage the cables and result in serious
malfunctions. Check again to ensure that no cables or any
other parts are in the way before you proceed.
26 Connecting the Gas Supply