Raypak 992B-1262B manual Safety Inspection, Follow-Up, Pilot Turn-Down Test

Safety Inspection

1.Check all thermostats and high limit settings.

2.During the following safety checks leave manome- ters hooked up, check and record.

3.If other gas-fired appliances in the room are on the same gas main, check all pressures on the Hi Delta with all other equipment running.

4.Check thermostats for ON-OFF operation.

5.Check high limits for ON-OFF operation.

6.While in operation, check flow switch operation.

7.Check the low gas pressure switch. (For proper adjustment, use the attached manometers, if available, to set pressure. The scales on the switch are approximate only.) Low gas pressure switch must be set at 5.0 in. WC for natural gas and 10.0 in. WC for propane gas.

8.Make sure that the high gas pressure switch (op- tional) is set to 1.0 in. WC above manifold pres-sure.

Follow-Up

Safety checks must be recorded as performed.

Turn heater on. After main burner ignition:

1.Check manometer for proper reading.

2.Cycle heater several times and re-check readings.

3.Remove all manometers and replace caps and screws.

4.Replace all gas pressure caps.

5.Check for gas leaks one more time.

Pilot Turn-Down Test

The Hi Delta heaters, depending on their size, have two to five burner sections. Each burner section is sup- plied gas by gas valves incorporated into a single valve body. A maximum of three burner sections may be controlled by a single hot surface ignition system. The middle of the three burner sections is ignited directly with a hot surface ignition system.

The burner section that is ignited directly by the hot surface ignition system serves as a supervised pilot to light the burner sections on either side of it. The burn- er sections on either side of the supervised section (pilot) are electrically interlocked with the supervised ignition system so as they are not energized unless flame is proven on the center section which is acting as a pilot to light the right and left-hand sections.

The pilot turn-down test is conducted as follows:

1.Turn off manual valves on non-supervised burner sections.

2.Turn on electrical power and adjust thermostat to call for heat.

3.Wait for completion of ignition sequence to light burner section being utilized as a pilot for those turned off in step 1 above.

4.Gradually reduce manifold pressure (flame) on supervised burner section by slowly closing man- ual gas valve. Watch for shut-down due to loss of supervised flame signal as pressure is being re- duced. Flame signal should be lost before manifold pressure goes below 2.0 in. WC for nat- ural gas and 6.0 in. WC for propane gas.

Leak Test Procedure: Dual-Seat Gas Valves

Proper leak testing requires three pressure test points in the gas train.

Test point A is upstream of the automatic gas valve. On the first automatic valve, this is a bleedle valve. On the other valves, this is a plugged port. The bleedle valve on the first valve may be used for all the other valves as well.

Test point B is a bleedle valve located between the two automatic gas valve seats.

Test point C is located downstream of both automatic gas valve seats and upstream of the manual valve. On the manual valve, this is a bleedle valve. Identical readings will be found at the plugged port labeled as Alternate C.

Refer to Fig. 45. The numbers on the diagram refer to the steps below:

These tests are to be conducted with the electrical power to the heater turned off.

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