Gas Supply Piping By Installer; Gas Bleeds And Vents By Installer; Boiler Water Piping; Piping Design - Patterson-Kelley MOD-04 Installation And Owner's Manual

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Modu-Fire Gas-Fired Boiler

3.7.1 Gas Supply Piping by Installer

The boiler and all gas piping connections should be
pressure-tested and must be checked for leaks be-
fore being placed into service. Test with com-
pressed air or inert gas if possible.
The boiler must be disconnected at the boiler man-
ual shut-off valve (located at the end of the supplied
gas train) from the gas supply piping system during
any pressure testing of the system at pressures in
excess of 1/2 psig (14 inch w.c.).
During any pressure testing of the gas supply piping
system at pressures equal to or less than 1/2 psig (14
inch w.c.), the boiler should be isolated from the gas
supply piping system by closing the manual shut-
off.
Some leak test solutions, including soap and water,
may cause corrosion. These solutions should be
rinsed-off with water after testing.

3.7.2 Gas Bleeds and Vents by Installer

If your unit is equipped with a diaphragm gas valve,
the bleed vents on the diaphragm gas valves have
been factory-piped to terminate at the burner, as re-
quired by ANSI Z21.13. This feature provides com-
bustion of any gas which leaks past a ruptured dia-
phragm during operation. Gas vents to outdoor air
must be provided for the main pressure regulator.
The pilot regulator is equipped with a vent limiting
device and does not require external venting!
•
When installing per ASME CSD-1, discon-
nect factory piped bleed vents and vent the
diaphragm gas valves to outdoor air (field
piping.)
If a N.O. (normally open) vent valve is provided, it
must be vented independently of any other bleeds
and vents. Discharge of vent lines should be pro-
tected by an insect screen.
The air gas ratio control valve is equipped with a
"reference chamber vent filter" which does not re-
quire any additional venting. This connection is
labeled COMBUSTION / ATMOSPHERE.
If local conditions require venting to outdoors, the
vent line connection must be piped by the installer
in accordance with the National Fuel Gas Code
(NFPA 54), ANSI Z223.1, which states:
"In the case of vents leading outdoors, means shall
be employed to prevent water from entering this
piping and also to prevent blockage of vents by in-
sects and foreign matter."
The National Fuel Gas Code Handbook goes on to
say that "Insects, insect nests, ice, or freezing rain
can block outdoor vents...."
The pilot regulator is equipped with a vent limiting
device and does not require external venting!
Gas Vents by Installer
Note: Provide a drip leg in all vent/bleed lines.
All vent lines should be pitched up at all times to
prevent building a trap into the vent line.
"Vent limiters" are NOT to be installed on this
boiler.
The air gas ratio control valve is equipped with a
"reference chamber vent filter" which does not re-
quire any additional venting.
3.8 B W
OILER ATER

3.8.1 Piping Design

Water Flow in System
Ideal operation of the P-K MODU-FIRE
would consist of a 20º F temperature differential
across the heat exchanger at High fire. Insufficient
flow may result in excessive short cycling of the
boiler and eventual damage or premature failure of
the equipment.
Minimum Return Water Temperature should be
greater than 130º F to avoid problems of condensa-
tion on the outside of the heat exchanger or in the
flue passages.
Proper flow rates and return water temperature may
be achieved through a combination of primary and
secondary flow loops. Multiple zones and pumps
may result in different flow rates at different times.
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Installation
P
IPING
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Boiler