1-25
BOILER SYSTEMS AND OPERATION
SL 35-199, SL 45-260 MODULATING GAS BOILERS
1.7 GAS PIPING
The boiler should have an inlet gas pressure of at least 5.0" w.c. for natural gas
or propane. 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 (female).
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
1/2" IPS
3/4" IPS
1" IPS
1-1/4" IPS
SL 35-199 (Natural Gas)
10’
40’
150’
600’
SL 35-199 (Propane)
30’
125’
40’
1,600’
SL 45-260 (Natural Gas)
N/A
30’
90’
350’
SL 45-260 (Propane)
20’
80’
250’
900’
Table 6: Maximum Pipe Length (ft)
Gas piping must have a sediment trap ahead of the boiler’s gas valve
(see Figure
29)
. 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 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 29: Typical gas piping connection
WARNING
This boiler model can burn
either Natural gas or Propane.
The boiler should be ordered
from the Factory configured
for the correct fuel. Examine
the rating plate of the boiler
to ensure it is configured
for the fuel you are using.
For example, if the boiler is
configured for Natural gas,
and it is to be converted to
Propane, a conversion kit
must be ordered from IBC
and the gas valve adjusted
accordingly. Refer to section
3.3 for further instruction.
Failure to perform the
required fuel conversion can
result in an immediate hazard.
NOTE
It is essential to check gas
supply pressure to each
boiler with a manometer or
other high-quality precision
measuring device. Pressure
should be monitored before
firing the boiler, when the
regulator is in a “lock-
up” condition and during
operation, throughout the
boiler’s full modulation range.
Pay special attention to
retrofit situations where
existing regulators may have
an over-sized orifice and/or
worn seats, causing pressure
“creep” and high lock up
pressures.
Summary of Contents for SL 35-199
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