Bradford-White Corp PDX50S60F(B, PDX75S70F(B, CX), C)*(N warranty Exhaust Pressure Switch Testing

PDX Series

PDX SERVICE PROCEDURE III

Pressure Switch Testing and

Replacement

Exhaust Pressure Switch		WARNING
Testing
		120 volt potential exposure. Use caution
Step 1.	Position power switch on gas control	making voltage checks to avoid personal injury.
	to the “OFF” position.
Step 2.	Remove the three screws (Phillips screw driver) from control access cover on blower assembly and
	remove cover (see photo 1).
Step 3.	Remove tubing and wires from inlet pressure switch.
Step 4.	Carefully remove pressure switch from blower housing (see photo 2)

Exhaust
pressure switch	1

Inlet pressure switch

Pressure switch

wire leads

With steps 1,2,3 & 4

complete,

disconnect wire leads from

pressure switch.

Use a multi-meter set to the
ohms setting. With blower off,						Check tubing and pressure
check across pressure			N
							tap on switch for blockage.
switch terminals.
								Is there blockage?
Are switch contacts open?
(no electrical continuity)									Y
	Y
								Clear blockage
Position gas valve power
switch to the “ON” position					Y
and adjust thermostat									Y
to call for heat,				Check tubing and
								Is vent
this will start the blower.		N		pressure tap on		N				N
								system
Check with multi-meter, do				switch for blockage.
								blocked
pressure switch contacts				Is there blockage?

close with blower running

with the switch in the

vertical postition?

Y

Switch contacts are OK. See safety circuit trace (page 30)

2

Pressure Switch

Slide pressure switch in direction of arrow while tilting slightly away from blower housing.

N	Replace switch
	(see page 18)

Is vent system length				Y
			See blower testing
within vent table		Y
			(page 21)
specifications
			Is blower OK?
listed on page 7
				N
	N
Reconfigure vent			Correct blower
system to be
compliant with			problem.
vent tables.

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