Thermon HELLFIRE 400, Installation, Operation & Maintenance Instructions Manual

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D.5 Heat Output Adjustment
1. Depending on the length of switch points, its’
priority, local climate conditions, and experience, the
operator can increase or decrease the heat output
accordingly. The recommended heat output is in the
range of 10,000 to 22,000 BTU/hr per foot of turnout
length.
2. The factory default setting is 400,000 BTU/hr
when operated on LPG, or 260,000 BTU/hr on NG.
The heater can be fueled with LPG or NG with no
component change.
3. Adjust the heat output as follows:
3.1 Using a flat blade screwdriver, remove the
regulator adjustment screw cap (shown).
3.2 Turn on the gas supply, turn on the heater and
set the manifold pressures as per the natural
gas limits on the heater nameplate. Rotate
the adjustment screw clockwise to increase
pressure.
3.3 If the burner fails to light after repeated
attempts, it may be necessary to purge the
main gas line of air.
3.4 After 15 minutes of running, verify the nozzle
temperatures are in the range of 38°C - 88°C
(100°F - 190°F) above ambient.
WARNING
WARNING.
Do not operate above maximum
manifold pressure as this can produce carbon
monoxide in excess of maximum allowable of
0.08
air free carbon monoxide (AFCO).
WARNING
WARNING.
Do not operate above or below the
rated manifold pressure limits. Operating outside
limits will result in weak flame signal and
unreliable operation.
3.5 Reinstall the cap to cover the regulator
adjustment screws.
3.6 The heat output can be estimated from the
manifold pressure and the following formulas:
200,000 + ((Manifold pressure –1.3)/3.7)*200,000 for LPG or
200,000 + ((Manifold pressure –2.3)/8.7)*200,000 for NG
Pressure is in inches of water column.
NOTE:
These formulas are simplified, assume the equipment is
in good condition, and are strictly for estimation only.
CAP