York TL9E Series Installation Manual page 24

5894307-UIM-B-0920
GAS PIPING LEAK CHECK
WARNING
!
FIRE OR EXPLOSION HAZARD
Failure to follow the safety warnings exactly could result in serious
injury, death, or property damage.
Never test for gas leaks with an open flame. Use a commercially
available soap solution made specifically for the detection of leaks to
check all connections. A fire or explosion may result causing property
damage, personal injury, or loss of life.
IMPORTANT: Burner ignition may not be satisfactory on first startup
due to residual air in the gas line or until gas manifold pressure is
adjusted. The ignition control makes three attempts to light before
locking out.
When the gas supply is first connected to the furnace, loosen the
ground union until the odor of gas is detected. When gas is detected,
immediately tighten the union and check for gas leaks. Allow 5 min for
any gas to dissipate before continuing with the startup procedure. Make
sure that proper ventilation is available to dilute and carry away any
vented gas.
With the furnace in operation, check all of the pipe joints, gas valve con-
nections, and manual valve connections for leakage using an approved
gas detector, a non-corrosive leak detection fluid, or other leak detec-
tion methods. Take appropriate action to stop any leak. If a leak per-
sists, replace the faulty component.
The furnace and its equipment shutoff valve must be disconnected from
the gas supply during any pressure testing of that system at test pres-
sures in excess of 0.5 psig (3.45 kPa).
The furnace must be isolated from the gas supply piping system by
closing the equipment shutoff valve during any pressure testing of the
gas supply system.
IGNITION CHECK
This furnace lights reliably and without undue ignition noise if the gas-
air mixture in the burner is correct. In most cases, it is not necessary to
make any adjustments to the factory settings. However, if the burner
does not light after several attempts, it may be necessary to adjust the
gas flow rate. Before attempting to adjust the gas flow rate, make sure
that the other necessary conditions for ignition are met (for example,
the gas valve is turned on, the main gas cock is open, and the igniter
comes on). If the burner does not light or lights and immediately goes
out, increase the gas pressure at the gas valve. If the burner does not
light even after the manifold pressure has reached 4.0 in., you may
have abnormally low gas heating value and it is necessary to change
the main gas orifice to a larger size.
24
IGNITION SYSTEM SEQUENCE
1. Turn the gas supply ON at external valve and main gas valve.
2. Set the thermostat above room temperature to call for heat.
3. System start-up occurs as follows:
a. The induced draft blower starts and runs for several seconds to
bring fresh combustion air into the combustion chamber. Then
the induced draft blower shuts off and the hot surface igniter
glows for about 17 s.
b. After this warm up, the induced draft blower starts again and the
ignition module opens the main gas valve.
c. After flame is established, the supply air blower starts in about
30 s.
WARNING
!
HOT SURFACE IGNITION SYSTEM
Do not attempt to light this furnace by hand (with a match or any other
means). There may be a potential shock hazard from the components
of the hot surface ignition system. The furnace can only be lit auto-
matically by its hot surface ignition system.
CALCULATING THE FURNACE INPUT
NOTICE
DO NOT set manifold pressure less than 3.0 in. W.C. or more than
4.0 in. W.C. for natural gas at sea level. If manifold pressure is out-
side this range, change main burner orifices.
NOTICE
If orifice hole appears damaged or it is suspected to have been
redrilled, check orifice hole with a numbered drill bit of correct size.
Never redrill an orifice. A burr-free and squarely aligned orifice hole is
essential for proper flame characteristics.
CAUTION
!
DO NOT bottom out gas valve regulator adjusting screw. This can
result in unregulated manifold pressure and result in excess overfire
and heat exchanger failures.
Verify natural gas input rate by clocking meter.
1. Turn off all other gas appliances and pilots.
2. Run furnace for a minimum of 3 min in heating operation.
3. Measure time (in seconds) for gas meter to complete one revolution
and note reading. The 2 cubic feet dial provides a more accurate
measurement of gas flow.
4. See Table 12 for cubic feet of gas per hour.
5. Multiply cubic feet per hour by heating value (BTU/cu. ft) to obtain
input.
If clocked rate does not match the input rate from the unit nameplate.
follow the steps in the next section to adjust the manifold pressure.
Repeat Steps 2 to 5 until correct input is achieved.
CAUTION
!
Be sure to relight any gas appliances that were turned off at the start
of this input check.
Johnson Controls Ducted Systems