Checking Gas Heat Input; Single Stage Gas Heat; Two Stage Gas Heat - York International ZQ Series Installation Manual

Checking Gas Heat Input

Single Stage Gas Heat

About this task:
This unit has a single stage of gas heat. The
intended input for each furnace is shown in Table
60. The table applies to units operating on 60 Hz
power only.
To determine the rate of gas flow (Single Stage).
1. Turn off all other gas appliances connected to
the gas meter.
2. Turn on the furnace and make sure the
thermostat is calling for heat.
3. Measure the time needed for one revolution
of the hand on the lowest increment dial on
the meter. A typical gas meter has a 1/ 2 or a 1
cubic foot test dial.
4. Using the number of seconds it takes for one
revolution of the dial, calculate the cubic feet
of gas consumed per hour. (See example
below).
5. If necessary, adjust the regulator as discussed
in the section "Manifold Gas Pressure
Adjustment". Be sure not to over-fire the
furnace. If in doubt, it is better to leave the
furnace slightly under-fired. Repeat Steps 1-5.

Two Stage Gas Heat

About this task:
This unit has two stages of gas heat. First stage
input is considered the minimum input for the
furnace. The intended input for each furnace
is shown in Table 60. The table applies to units
operating on 60 Hz power only.
To determine the rate of gas flow (Second Stage).
1. Turn off all other gas appliances connected to
the gas meter.
2. Turn on the furnace and make sure the
thermostat is calling for Second stage (100%
input) heat.
3. Measure the time needed for one revolution
of the hand on the lowest increment dial on
the meter. A typical gas meter has a 1/2 or a 1
cubic foot test dial.
76 INSTALLATION MANUAL ZQ SERIES 3 - 5 ton 60 Hertz R-410A
4. Using the number of seconds it takes for one
revolution of the dial, calculate the cubic feet
of gas consumed per hour. (See example
below)
5. If necessary, adjust the high pressure
regulator as discussed in the section
Gas Pressure
over-fire the furnace on second stage. If in
doubt, it is better to leave the second stage of
the furnace slightly under-fired. Repeat Steps
1-5.
To determine the rate of gas flow (First Stage)
1. Turn off all other gas appliances connected to
the gas meter.
2. Turn on the furnace and make sure the
thermostat is calling for first stage heat.
3. Even when the thermostat is calling for first
stage heat, the unit will light on second stage
and will run on second stage for 1 minute.
Allow this one-minute time period to expire
and be certain the unit is running on first
stage.
4. Measure the time needed for one revolution
of the hand on the lowest increment dial on
the meter. A typical gas meter has a 1/2 or a 1
cubic foot test dial.
5. Using the number of seconds it takes for
one revolution of the dial, calculate the cubic
feet of gas consumed per hour (See example
below).
6. If necessary, adjust the low pressure regulator
as discussed in the section "Manifold Gas
Pressure Adjustment". Be sure not to under-
fire the furnace on first stage. If in doubt, it
is better to leave the first stage of the furnace
slightly over-fired (Refer to Table 60 for input
value). Repeat Steps 1-6.
Table 59: Gas Rate Cubic Feet Per Hour
Seconds forOne Rev.
10
12
14
16
18
20
22
24
26
28
Johnson Controls Ducted Systems
Manifold
Adjustment. Be sure not to
Size of Test Dial
1/2 cu. ft. 1 cu. ft.
180 360
150 300
129 257
113 225
100 200
90 180
82 164
75 150
69 138
64 129