Cambridge Engineering, Inc.
26
M-Series Technical Manual
IMPORTANT
Refer to the heater rating plate for determining
the minimum gas supply pressure for obtaining
the maximum gas capacity for which this heater
is specified.
1. Check with the local utility or gas supplier for the
facility gas supply pressure.
m
CAUTION:
If the gas supply pressure is in excess of the maxi-
mum pressure indicated on the heater nameplate,
a separate positive shut-off high pressure regula-
tor must be added upstream of the heater’s indi-
vidual manual shut-off valve. This regulator must
be vented to the outside of the building at least
10 feet from any intake opening or 4 feet above
the heater. The vent pipe should be designed to
prevent the entry of water, snow, insects or other
foreign material that could cause blockage. There
must be no reduction in the size of the vent pip-
ing. Depending on the length and the configuration
of the vent piping the pipe size may need to be
increased. Refer to the applicable codes for proper
sizing.
m
WARNING:
For roof mounting, the gas and electrical connec-
tions must not penetrate the unit base or mounting
curb. Cambridge Engineering recommends using
pitch pockets or decktite to seal the penetrations.
2. Properly size the gas supply piping for the rated
capacity, per local codes, and/or the National Fuel
Gas Code, ANSI Standard Z223.1 or the CAN/CGA
B149 Installation Codes.
3. Make sure the supply piping is free of foreign matter
and purged.
4. Verify that the gas piping, when installed, will not
restrict or block the access door from fully opening.
5. Install gas piping to the make-up air heater in
accordance with local codes or, in their absence,
in accordance with the National Fuel Gas Code,
ANSI Standard Z223.1, or the CAN/CGA B149
Installation Codes.
IMPORTANT
A 1/8" NPT tap is supplied with the heater for
measuring the gas supply pressure. If the gas
supply pressure exceeds that indicated on the
nameplate, the installer must install a 1/8" NPT
tap and high pressure manual shut-off valve
upstream of the high gas pressure regulator.
IMPORTANT
An adequate sediment trap must be installed
prior to all gas controls for the heater and as
close to the gas inlet connection of the heater
as practical. Many gas train components are
equipped with listed Vent Limiters as atmo-
spheric bleeds, however, local codes may
require that these vents and bleeds be vented
to the outdoors. If so, the vent piping should be
designed to prevent the entry of water, snow,
insects or other foreign materials that could
cause blockage.
6.
Check for leaks in the supply piping system. Use
liquid gas leak detector. Do NOT use flame.
m
CAUTION:
If the test pressure is in excess of 1/2 PSIG (3.5
KPA), the heater and its manual shut-off valve must
be disconnected from the gas supply system during
pressure testing. Failure to comply will void the
warranty.
If the test pressure is less than or equal to 1/2 PSIG
(3.5 KPA), the heater must be isolated from the gas
supply
piping by closing its manual shut-off valve during
pressure testing.
m
CAUTION:
Do not attempt to start the
make-up air heater at this time.
Premature start-up can result in damage to the
equipment and components.
INSTALLATION INSTRUCTIONS
GAS PIPING
