Delta PG PLUS-25 Verify Correct Pressure Switch, Air Shutter Settings, Check Thermostat Circuit

Start-Up Preparations

Verify Correct Pressure Switch

1.Remove the burner hood and verify the burner pressure switch setting.

2.Check and compare the color of the out- line on the pressure switch label to Table 3 page 49.

NOTICE

The PERFORMANCE PLUS is equipped with an air pressure switch, which provides a safe means of shutting down the unit due to a blockage of the combustion air inlet. The switch is “nor- mally closed” and measures the change in the negative pressure (vacuum) creat- ed by the burner blower.

Verify Correct Air Shutter Setting

-Check and verify the air shutter setting as listed in Table 4.

-The air shutter is located inside the com- bustion air inlet adapter located in the top /left jacket panel area. See Fig. 37.

Table 4 : Air Shutter Settings

Model	Natural Gas	Propane
PG PLUS-25	2.5	2.5
PG PLUS-30	2.5	2.5
PG PLUS-35	1	2.0
PG PLUS-40	N/R	0
PG PLUS-45	N/R	0

NR- Air shutter not required.

Check Thermostat Circuit

-Unplug the Room Thermostat Snap-set located on the rear of the unit.

-Connect a voltmeter across the end ter- minals of the male half of the Room Thermostat Snap-set.

-Close each thermostat, zone valve and relay in the external circuit one zone at a time and check the voltage reading across the plug.

-There should NEVER be voltage mea- sured at the plug.

-If voltage is measured at the plug under any condition, check and correct the external wiring.

NOTICE

In systems using 3-wire zone valves backfeed of voltage to the unit is a com- mon problem. Use an isolation relay to prevent voltage from the external circuit entering the Room Thermostat Snap-set.

Fig. 37: Air Shutter Adjustment

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