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Operating Gauge Set and Service Valves
TORQUE REQUIREMENTS
When servicing or repairing heating, ventilating, and air
conditioning components, ensure the fasteners are appro-
priately tightened. Table 2 lists torque values for fasteners.
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 #C-08-1
for further details and information.
IMPORTANT
To prevent stripping of the various caps used, the
appropriately sized wrench should be used and fitted
snugly over the cap before tightening.
TABLE 1. Torque Requirements
Parts
Recommended Torque
Service valve cap
8 ft.- lb.
11 NM
Sheet metal screws
16 ft.- lb.
2 NM
Machine screws #10
28 ft.- lb.
3 NM
Compressor bolts
90 in.- lb.
10 NM
Gauge port seal cap
8 ft.- lb.
11 NM
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 with HFC-410A refrigerant sys-
tems must be capable of handling the higher system oper-
ating pressures. The gauges should be rated for use with
pressures of 0 - 800 psig on the high side and a low side
of 30” vacuum to 250 psig with dampened speed to 500
psi. Gauge hoses must be rated for use at up to 800 psig
of pressure with a 4000 psig burst rating.
OPERATING SERVICE VALVES
The liquid and vapor line service valves are used for re-
moving refrigerant, flushing, leak testing, evacuating,
checking charge and charging. Each valve is equipped
with a service port which has a factory-installed valve
stem. Figure 2 provides information on access and opera-
tion of both angle and ball service valves