Installation
20 RT-SVX058D-EN
Gas Heat Data
Table 3. Gas heater operating data
Heating Input Rate—
Btu/h 115,000 100,000 72,000
Minimum Supply Gas
Pressure Natural/LP
4/11 4/11 4/11
Manifold Gas Pressure
(a)
(a) Staged gas heat units have a positive pressure gas valve. Never ad-
just the staged gas pressure valve to a negative pressure.
3.5 3.5 3.5
Combustion Blower Suction
Pressure
(1
st
Stage)
-0.50 to -
0.55
-0.50 to -
0.55
-0.50 to -
0.55
Combustion Blower Suction
Pressure
(2
nd
Stage)
-0.65 to -
0.70
-0.65 to -
0.70
---
Minimum Flame Sensing
Current
(b)
(b)A voltage reading across pens (V+) & (V-) is equatable to the flame
sensing current. One volt equals one micro amp.
5.0 Micro Amps DC
Normal Sensing Current
Range
8.0 to
16 Micro Amps DC
Flue Gas Temperature Rise
Above Ambi
ent
250 to 350 F
Flue Gas Content - % CO
2
6.5 to 9.0 %
Natural LP 8.0 to 10.5%
Minimum Supply Air
Temperatur
e Across Heat
Exchanger
40 F
Table 4. Piping
Length of
Pipe (ft)
Iron Pipe Size (IPS) Inches
½” Pipe ¾” Pipe 1” Pipe 1¼” Pipe 1½” Pipe
15 76 176 345 750 1220
30 52 120 241 535 850
45 43 99 199 435 700
60 38 86 173 380 610
75 77 155 345 545
Note: Capacity of Pipe of Different Diameters and Lengths in Cu. Ft. Per
Hr. with Pressure Drop of 0.3" and Specific Gravity of 0.60
Table 5. Specific gravity multipliers
Specific Gravity Multipliers
0.50 1.10
0.55 1.04
0.60 1.00
0.65 0.96
Figure 17. Schematic diagram for field gas piping to
units
Figure 18. Typical unit gas train configuration
Voltage Imbalance
Three phase electrical power to the unit must meet
stringent requirements for the unit to operate properly.
Measure each leg (phase-to-phase) of the power supply.
Each reading must fall within the utilization range stamped
on
the un
it nameplate. If any of the readings do not fall
within the proper tolerances, notify the power company to
correct this situation before operating the unit.
Excessive three phase voltage im
balance between phases
will cause motors to overhe
at and eventually fail.
The maximum allowable voltage imb
alance is 2 percent.
Measure and record the voltage between phases 1, 2, and
3 and calculate the amount of imbalance as follows:
% Voltage Imbalance =
100 X AV - VD
where;
AV
AV (Average Voltage) =
Volt 1 + Volt 2 + Volt 3
3
To Next Page
Loading...
