Gas Piping - IBC DC 23-84 Installation And Operating Instructions Manual

Figure 31: Gas Valve
1-30
DC SERIES COMBI BOILERS DC 23-84, DC 29-106, DC 33-124, DC 33-160
1.8

GAS PIPING

The boiler should normally have an inlet gas pressure of at least 7.0" w.c. for
natural gas and 11" w.c. for propane gas. For either fuel, the inlet pressure shall
be no greater than 14.0" w.c. Confirm this pressure range is available with your
local gas supplier.
The inlet gas connection of the boiler's gas valve is 1/2" NPT (male).
Adequate gas supply piping shall be provided with no smaller than 1/2" Iron Pipe
Size (e.g. Iron Pipe Size (IPS) and using a 1" w.c. pressure drop, in accordance
with the following chart:
MODEL
DC Series (Natural Gas)
DC Series (Propane)
Table 7: Maximum Pipe Length (ft) – DC series 33-160 boiler
Gas piping must have a sediment trap ahead of the boiler's gas valve (see Figure
32). A manual shutoff valve must be located outside the boiler, in accordance
with local codes/standards. All threaded joints in gas piping should be made with
an approved piping compound resistant to the action of natural gas/propane. Use
proper hangers to support gas supply piping as per applicable codes.
The boiler must be disconnected or otherwise isolated from the gas supply
during any pressure testing of the system at test pressures in excess of 1/2 psig.
Dissipate test pressure prior to reconnecting. The boiler and its gas piping shall
be leak tested before being placed into operation.
•
The boiler and its individual shutoff valve must be disconnected from the
gas supply piping system during any pressure testing of that system at test
pressures in excess of 1/2 psi (3.5 kPa).
•
The boiler must be isolated from the gas supply piping system by closing,
disconnecting and capping its individual manual shutoff valve during any
pressure testing of the gas supply piping system at test pressures equal to or
less than 1/2 psi (3.5 kPa).
The gas valve is provided with pressure taps to measure gas pressure upstream
(supply pressure) and downstream (manifold pressure) of the gas valve (see
Figure 31). Note that manifold pressure varies slightly in accordance with firing
rates with the modulating series boilers, but will always be close to 0" w.c.
Figure 32: Gas Piping
1/2" IPS 3/4" IPS
20' 70'
50' 200'
INSTALLATION AND OPERATION INSTRUCTIONS
1" IPS
200'
600'