Chromalox PQ404-6 specifications Operation cont’d, Typical Wiring for Automatic Blowdown System

OPERATION (cont’d.)

Now turn the wheel on the large timer until the “off” tab passes the “time now” arrow. The “boiler normal” light should go out and the valve should begin to open. Once the “valve open” light goes on, the valve should remain open for a few seconds and then automatically close. The “drain valve closed” light should light and the “boiler nor- mal” light should remain off.

NORMAL OPERATION – Set the “Boiler Normal/24-hour duty” switch located on the inside of the control panel to “boiler normal” if the boiler is to be shut down each night. Set it to “24-hour duty” if the boiler is to remain on continuously 24 hours per day (except during blowdown).

Set the tabs on the large timer for the ON and OFF times desired for the boiler, screw in the small black day-skip tabs if the boiler is to remain off for the weekend, etc.

If the boiler is on 24-hour duty set the OFF tab for the time that is desired for blowdown. The ON tab can be ignored, but must remain on timer.

The small time delay relay controls the time that the drain valve remains open. Counterclockwise decreases, clockwise increases blow- down time. Time must be adjusted by trial.

Figure 16 – Typical Wiring for Automatic Blowdown System

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