Keating Of Chicago Miraclean Thermostat Bulb Placement Detail, A. Burner Coil Check

THERMOSTAT BULB PLACEMENT DETAIL

MILLIVOLT CHECK (FOR QUALIFIED SERVICE TECHNICIANS ONLY)

The millivolt valve is a thermopile self-powered combination gas control. Before checking the millivolt system, the following operations should be performed and observations made:

1.A genuine Keating millivolt thermostat should be used for millivolt operation.

2.The thermostat leads and all wire connections should be cleaned and tightened to eliminate all unnecessary resistance.

3.If pilot will not remain lit when gas valve knob is released, check automatic pilot.

NOTE: The millivolt system and individual components may be checked with a millivolt meter having a 1-1000MV range. Conduct each check below by connecting meter test leads to terminals as indicated. All readings are closed circuit.

		CONNECT METER LEADS TO		THERMOSTAT	METER READING
CHECK	TO TEST		TERMINALS	CONTACTS	SHOULD BE:
A	BURNER COIL	TP	TH	CLOSED	100mV OR MORE
B	THERMOPILE OUTPUT	THTP	TP	OPEN	BETWEEN 325–700mV
C	THERMOSTAT LOAD	THTP	TH	CLOSED	DROPS LESS THAN 80mV
D	AUTOMATIC PILOT DROPOUT	THTP	TP	OPEN	BETWEEN 75-25 mV

A. BURNER COIL CHECK

(“A” Reading. Thermostat contacts CLOSED - Gas Valve knob “ON”. Main burner should come ON.)

1.If the reading is more than 100 millivolts and the automatic valve still does not come one, replace the valve.

2.If the closed circuit reading (“A” reading) is less than 100 millivolts, determine cause for low reading and proceed as follows:

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