Bryant 558D Pre-Start-Up, I. Heating Section Start-Upand Adjustments, C. Limit Switches

PRE-START-UP

WARNING: Failure to observe the following warn- ings could result in serious personal injury:

1.Follow recognized safety practices and wear pro- tective goggles when checking or servicing refrig- erant system.

2.Do not operate compressor or provide any electric power to unit unless compressor terminal cover is in place and secured.

3.Do not remove compressor terminal cover until all electrical sources have been disconnected.

4.Relieve all pressure from system before touching or disturbing anything inside terminal box if refrigerant leak is suspected around compressor terminals.

5.Never attempt to repair soldered connection while refrigerant system is under pressure.

6.Do not use torch to remove any component. Sys- tem contains oil and refrigerant under pressure. To remove a component, wear protective goggles and proceed as follows:

a.Relieve all pressure from system.

b.Cut component-connecting tubing with tubing cutter and remove component from unit.

c.Carefully unsweat remaining tubing stubs when necessary. Oil can ignite when exposed to torch ¯ame.

Proceed as follows to inspect and prepare the unit for initial start-up:

1.Remove all access panels.

2.Read and follow instructions on all WARNING, CAU- TION and INFORMATION labels attached to, or shipped with, unit.

3.Make the following inspections:

a.Inspect for shipping and handling damages such as broken lines, loose parts, disconnected wires, etc.

b.Inspect for oil at all refrigerant tubing connections and on unit base. Detecting oil generally indicates a refrigerant leak. Leak-test all refrigerant tubing con- nections using electronic leak detector, halide torch, or liquid-soap solution. If refrigerant leak is de- tected, see Refrigerant Leaks section on page 30.

c.Inspect all ®eld- and factory-wiring connections. Be sure that connections are completed and tight.

d.Inspect coil ®ns. If damaged during shipping and han- dling, carefully straighten ®ns with a ®n comb.

4.Verify the following conditions:

a.Make sure that condenser-fan blade is positioned cor- rectly in fan ori®ce. Blades should clear fan motor and fan ori®ce ring.

b.Make sure that air ®lters are in place.

c.Make sure that condensate drain pan and trap are ®lled with water to ensure proper drainage.

d.Make sure that all tools and miscellaneous loose parts have been removed.

5.Compressors are internally spring mounted. Do not loosen or remove compressor holddown bolts.

6.Each unit system has 4 Schrader-type gage ports: one on the suction line, one on the liquid line and two on the compressor discharge line. Be sure that caps on the ports are tight.

Unit is now ready for initial start-up.

START-UP

I. HEATING SECTION START-UP AND ADJUSTMENTS

CAUTION: Complete the required procedures given in Pre-Start-Up section on this page before starting unit.

Do not jumper any safety devices when operating the unit.

A. Checking Heating Control Operation

Start and check the unit for proper heating control operation as follows:

1.Turn on unit electrical supply.

2.Set system switch selector at HEAT position and fan switch at AUTO. or ON position. Set heating temperature lever above room temperature.

3.The evaporator fan will start immediately, and electric heater will be energized.

4.Check for heating operation by verifying that unit sup- ply outlets are functional.

5.The evaporator fan and heaters will turn off after ther- mostat temperature is satis®ed.

B.Heating Sequence of Operation

Room thermostat calls for heat, closing circuit between R and W1 24-v control terminals. Power to terminal R is supplied through the 24-v transformer, which is internally protected against overload. The 24-v power energizes the indoor (evapo- rator) fan relay (IFR). The IFR closes normally open contacts 2 to 4, which energize the indoor (evaporator) fan contactor (IFC) and the electric heat contactor, and start the indoor (evapo- rator) fan motor (IFM). There is no time delay in the start-up of the IFM.

When the call for heat is satis®ed, then the R to W1 circuit is opened and the IFR and IFC are deenergized.

Additional information on economizer operating in the heat- ing only mode is provided in Ventilation Sequence section on page 27.

C. Limit Switches

The heating limit switches (LS) are normally closed. If the leaving-air temperature exceeds the maximum allowable tem- perature, one of the limit switches will open, breaking the power circuit to the heater. This causes the heater to shut down immediately. Check the air quantity to ensure there is sufficient air¯ow.

If unit does not energize, reset the normally closed manual limit switch (LSM). The LSM reset button is located on the fan housing, and will only open in the event of a fan failure.

D. Air¯ow and Temperature Rise

The heating operation air¯ow must produce a temperature rise that falls within the approved cfm range (300 to 500 cfm per 12,000 Btuh cooling).

Refer to Indoor Air¯ow and Air¯ow Adjustments section on page 19 to adjust heating air¯ow where required.

E. Safety Check of Limit Control

A manual reset limit control is located on the evaporator fan. The control shuts off the unit in the event of fan failure.

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