Lennox International Inc 06/11 50672801 Caps and Fasteners Torque Requirements

Caps and Fasteners Torque Requirements

IMPORTANT

Only use Allen wrenches of sufficient hardness (50Rc − Rockwell Harness Scale minimum). Fully insert the wrench into the valve stem recess.

Service valve stems are factory−torqued (from 9 ft−lbs for small valves, to 25 ft−lbs for large valves) to prevent refrigerant loss during shipping and handling. Using an Allen wrench rated at less than 50Rc risks rounding or breaking off the wrench, or stripping the valve stem recess.

See the Lennox Service and Application Notes Corp.0807−L5 (C−08−1) for further details and information.

When servicing or repairing HVAC equipment and components, ensure the fasteners are appropriately tightened. Table 1 list torque values for various caps and fasteners.

Table 1. Torque Requirements

Parts	Recommended Torque
Service valve cap	8 ft.− lb.	11 NM
Sheet metal screws	16 in.− lb.	2 NM
Machine screws #10	28 in.− lb.	3 NM
Compressor bolts	90 in.− lb.	10 NM
Gauge port seal cap	8 ft.− lb.	11 NM

Operating Gauge Set and Service Valves

IMPORTANT

To prevent stripping of the various caps used, the appropriately sized wrench should be used and fitted snugly over the cap before tightening.

OPERATING SERVICE VALVES

The liquid and vapor line service valves are used for refrigerant recovery, flushing, leak testing, evacuating, weighing in refrigerant and optimizing system charge.

Each valve is equipped with a service port which has a factory−installed valve core. Figure 2 provides information on how to access and operate both angle− and ball−type service valves.

USING MANIFOLD GAUGE SET

When checking the system charge, only use a manifold gauge set that features low−loss anti−blow back fittings.

Manifold gauge set used for HFC−410A refrigerant systems must be capable of handling the higher system operating pressures. The manifold gauges should be rated for:

SHigh side

square inch gauge (psig)

SLow side sig with dampened speed to 500 psig

SManifold gauge set hoses must be rated for use to 800 psig of pressure with a 4000 psig burst rating.

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