Bradford-White Corp M4TW50T*F, M4TW60T*F, M2TW50T*F, M2TW65T*F Blower Temperature Switch Testing

TTW SERVICE PROCEDURE V

Blower Temperature Switch Testing

and Replacement

Blower Temperature Switch Testing.

Step 1. Position power switch on gas control to the “OFF” position.

WARNING

115 volt potential exposure. Use caution

to avoid personal injury.

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Step 2. Remove the three screws (Phillips screw driver) from control access cover on blower and remove cover (see photo 14).

Step 3. Locate blower temperature switch (see photo 15)

Switch Setting									15	Blower temperature
Opens on rise @ approximately 165°F										switch location
Auto resets on fall @ approximately 130°F
Cool switch to
below 130°F
										Air mixing inlet
Disconnect wire leads to
switch. Using a multi-meter N					Replace switch
set to the ohms setting, is
					(see page 23)
there continuity between
the switch terminals?
	Y
						N				Common causes for
Reconnect wire leads and										high exhaust temperature
observe heater operation.			Y		Do switch		Y	Exhaust		1. Vent length is below minimum allowable.
Do exhaust gas								temperature is		2. Vent diameter not to specification.
					contacts open?
temperatures rise to or								too hot.		3. Restricted dilution air inlet.
above 170°F										4. Missing or deteriorated flue baffle.
with vent connected?										5. Gas pressure is out of specification.
	N
Do switch		Y		Replace switch
contacts open?					(see page 23)

N

Switch OK

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