18
Installation Example
Elevation:
................................................... 5,000 feet
Type of Gas:
............................................Natural Gas
Local Heating Value of Gas:
...............................750
Determine which natural gas table to use. From
, find 750 and follow down the column,
stop at the 5,000 feet row. The heating value listed is
LOW.
orifice size and verify manifold pressure.
After the gas piping to the furnace is complete, all
connections must be tested for gas leaks. This includes all
fittings, pipe connections at the main gas valve, emergency
shutoff valve, and flexible gas connectors (if applicable).
The soap and water solution can be applied on each
joint or union using a small paintbrush. If any bubbling is
observed, the connection is not sealed adequately and
must be retightened. Repeat the tightening and soap
check process until bubbling ceases.
CAUTION:
When pressure testing gas supply lines at
pressures greater than 1/2 psig (14 inch W.C.), the
gas supply piping system must be disconnected
from the furnace to prevent damage to the gas
control valve. If the test pressure is less than or
equal to 1/2 psig (14 inch W.C.), close the manual
shut-off valve
Flue Gas Sampling
It may be necessary to take flue gas sampling in order
to check the performance after furnace installation. A
flue gas sample may be taken from the heat exchanger,
which is located behind the hole of the top-front of blower
compartment.
1. Turn off all electric power to the appliance.
2. Remove the black plastic cap located above the blower.
Do not discard cap.
3. Drill a hole through the top of the blower compartment.
NOTE:
Hole diameter should be same size as sampling
tube.
4. Insert sampling tube through the drilled hole and into
the heat exchanger.
5. After a complete check and adjustment of furnace
performance, seal the drilled hole with a screw larger
than the hole.
NOTE:
Seal the screw threads with silicon
sealant - rated at least 500° F.
6. Plug the outside hole with the plastic cap removed in
step 3.
High Altitude Conversion
WARNING:
The reduction of input rating necessary for high
altitude installation may only be accomplished
with factory supplied orifices. Do not attempt to
drill out orifices in the field. Improperly drilled
orifices may cause fire, explosion, carbon
monoxide poisoning, personal injury or death.
High altitude conversion with this furnace depends on
the installation altitude and the heating value of the gas.
The installation of this furnace at altitudes above 2,000
feet must meet the requirements of the National Fuel Gas
Code or local jurisdiction. In Canada, the requirements for
high altitude are different and governed by CSA B149.1.
Always consult your local code authority.
This furnace is shipped from the factory with orifices and
gas regulator settings for natural gas operation at sea
level altitudes. At 2,000 feet, the NFGC requires that this
appliance be derated 4% for each 1000 feet of altitude. For
example, the input needs to be reduced 8% at 2,000 feet,
12% at 3,000 feet and etc. This deration is in reference to
the input rate and gas heating value at sea level.
To derate the furnace requires knowing the heating value of
the gas at the installation site. Heating values at particular
job sites vary for two reasons:
1. The chemical mixture of the gas varies from region to
region and is expressed as the “sea level heating value”.
2. The heating value varies by altitude. For this reason,
especially in high altitude areas, the local gas utility
specifies the heating value at the residence’s gas meter
as the “local value”.
For added flexibility, two tables have been provided for
natural gas installations with high or low heating values
at sea level.
contain the manifold pressure and orifice sizes to use
installations with a heating value of more than 1,000 Btu
(LOW) is for less than 1,000
Btu per cubic foot. To determine which table to use:
1. Consult the local utility for the local heating value at
your installation site.
2. From
, find your local heating value
as supplied by the utility company. Follow down the
column and stop at your altitude level.
3. If your sea level heating value is HIGH, use
. See
.
After changing the orifices, it is required that you measure
the gas input rate. This may be accomplished in the usual
way, by clocking the gas meter and using the local gas
heating value. See Verifying Input Rate (
IMPORTANT NOTE:
Observe the action of the burners to make sure there
is no yellowing, lifting or flashback of the flame.
Summary of Contents for MG1 Series
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