Johnson Controls TG9S'MP UIM-H-0712, Ignition System Sequence, Hot Surface Ignition System

364861-UIM-H-0712

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 will occur as follows:

a.The induced draft blower motor will start and come up to speed. Shortly after inducer start-up, the hot surface igniter will glow for about 17 seconds.

b.After this warm up, the ignition module will energize (open) the main gas valve.

c.After flame is established, the supply air blower will start in about 30 seconds.

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 automatically by its hot surface ignition system.

CALCULATING THE FURNACE INPUT (NAT. GAS)

Burner orifices are sized to provide proper input rate using natural gas

with a heating value of 1030 BTU/Ft3 (38.4 MJ/m3). If the heating value of your gas is significantly different, it may be necessary to replace the orifices.

NOTICE

DO NOT set manifold pressure less than 3.2” w.c. or more than 3.8” w.c. for natural gas at sea level. If manifold pressure is outside 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.

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 minutes in heating operation.

3.Measure time (in sec) for gas meter to complete 1 revolution and note reading. The 2 cubic feet dial provides a more accurate mea- surement of gas flow.

4.Refer to Table 14 for cubic feet of gas per hour.

5.Multiply cubic feet per hour by heating valve (BTU/cu ft) to obtain input.

If clocked rate does not match the input rate from the unit nameplate. follow steps in next section to adjust the manifold pressure. Repeat steps 2 - 5 until correct input is achieved.

Be sure to relight any gas appliances that were turned off at the start of this input check.

30 Johnson Controls Unitary Products