Sunlife Enterprises DM300, DM240 Troubleshooting, GAS Rate Cubic Feet PER Hour, Belt Drive Blower

356214-XIM-A-0108

of the regulator setting), replace the orifice spuds with spuds of the proper size.

NOTE: To find the Btu input, multiply the number of cubic feet of gas consumed per hour by the Btu content of the gas in your particular locality (contact your gas company for this information - it varies widely from city to city.)

TABLE 23: GAS RATE - CUBIC FEET PER HOUR

Seconds	Size of Test Dial
for One
	1/2 cu. ft.	1 cu. ft.
Rev.
4	450	900
6	300	600
8	228	450
10	180	360
12	150	300
14	129	257
16	113	225
18	100	200
20	90	180
22	82	164
24	75	150
26	69	138
28	64	129

Example: By actual measurement, it takes 13 seconds for the hand on the 1- cubic foot dial to make a revolution with just a 300,000 Btuh furnace running. Read across to the column in the table above, headed “1 Cubic Foot”, where you will see that 278 cubic feet of gas per hour are consumed by the furnace at that rate. Multiply 278 x 1050 (the Btu rating of the gas obtained from the local gas company). The result is 292,425 Btuh, which is close to the 300,000 Btuh rating of the furnace.

ADJUSTMENT OF TEMPERATURE RISE

The temperature rise (or temperature difference between the return air and the heated air from the fur- nace) must lie within the range shown on the rating plate and the data in the Gas Heat Application Table 4.

BELT DRIVE BLOWER

All units have belt drive single-speed blower motors. The variable pitch pulley on the blower motor can be adjusted to obtain the desired supply air CFM.

TROUBLESHOOTING

COOLING TROUBLESHOOTING GUIDE

Troubleshooting of components may require opening the electrical control box with the power connected to the unit. Use extreme care when working with live circuits! Check the unit nameplate for the correct line voltage and set the voltmeter to the correct range before making any connections with line termi- nals.

When not necessary, shut off all electric power to the unit prior to any of the following mainte- nance procedures so as to prevent personal injury.

Label all wires prior to disconnection when ser- vicing controls. Wiring errors can cause improper and dangerous operation, which could cause injury to person and/or damage unit components. Verify proper operation after servicing.

On calls for cooling, if the compressors are operating but the supply air blower motor does not energize after a short delay (the room thermostat fan switch is in the

CFM =

Btuh Input x 0.8

“AUTO” position).

108. x oF Temp. Rise

After the temperature rise has been determined, the cfm can be calculated as follows:

After about 20 minutes of operation, determine the fur- nace temperature rise. Take readings of both the return air and the heated air in the ducts (about six feet from the furnace) where they will not be affected by radiant heat. Increase the blower cfm to decrease the temper- ature rise; decrease the blower cfm to increase the rise. Refer to the Blower Motor and Drive Data Table 18.

1.Turn the thermostat fan switch to the ON position. If the supply air blower motor does not energize, go to Step 3.

2.If the blower motor runs with the fan switch in the ON position but will not run after the first compres- sor has energized when the fan switch is in the AUTO position, check the room thermostat for con- tact between R and G in the AUTO position during calls for cooling.

Johnson Controls Unitary Products 45