Puron® (R-410A) Quick Reference Guide - Bryant SM03-4 Service Manual

Eventually, the total number of heaters is cycled on. In emergency
heat mode, LED indicator signals 7 flashes.
The amount of emergency heat available depends on whether
jumper JW1 is cut and the number of heating elements. Table 13
illustrates results under various conditions. The heaters cycle on
two elements initially and an additional element every 5 minutes
until maximum level is reached.
TABLE 13—EFFECT OF JW1 ON EMERGENCY HEAT
JW1 cut*
4 elements
50%
JW1 not cut
4 elements
100%
* Outdoor thermostat opens
With JW1 cut, an outdoor thermostat (if closed) could cycle on
additional heaters and system would perform as if JW1 was not
cut. In effect, closed outdoor thermostat replaces cut jumper.
H. Defrost
In defrost mode, LED indicator signals 6 flashes. Defrost is
initiated by heat pump and is signalled to smart control by an input
to W2D terminal. During defrost, outdoor unit switches to cooling
mode, making it necessary to cycle on electric heaters to temper
indoor air.
If electric heaters were not energized prior to defrost, smart control
energizes sufficient elements to temper air. If heaters were
energized prior to defrost, additional heaters will be cycled on to
provide additional heat.
A defrost initiation signal can be confirmed by attaching voltmeter
leads across low-voltage terminals W2D and C. If 24v is not
observed, check the following:
• Is 24v available across R and C? See Ready-To-Start section
for items to check if 24v is not available.
• Is there continuity in thermostat leads between heat pump
and smart control?
• Is defrost control in heat pump operating properly?
3 elements
66.7%
3 elements
100%
—50—
→ PURON® (R-410A) QUICK REFERENCE GUIDE
FOR INSTALLERS AND TECHNICIANS
• Puron (R-410A) refrigerant operates at 50-70 percent higher
pressures than R-22. Be sure that servicing equipment and
replacement components are designed to operate with Puron
(R-410A).
• Puron (R-410A) refrigerant cylinders are rose colored.
• Recovery cylinder service pressure rating must be 400 psig,
DOT 4BA400 or DOT BW400.
• Puron (R-410A) systems should be charged with liquid refrig-
erant.
• Use a commercial type metering device in the manifold hose.
• Manifold sets should be at least 750 psig high-side and 200 psig
low-side with 520 psig low-side retard.
• Use hoses with 750 psig service pressure rating.
• Leak detectors should be designed to detect HFC refrigerant.
• Puron (R-410A), as other HFC's, is only compatible with POE
oils.
• Vacuum pumps will not remove moisture from oil.
• Do not use liquid-line filter driers with rated working pressures
less than 600 psig.
• Do not install a suction-line filter drier in liquid line.
• POE oils absorb moisture rapidly. Do not expose oil to
atmosphere.
• Wrap all filter driers and service valves with wet cloth when
brazing.
• A liquid-line filter drier is required on every unit.
• Indoor unit is equipped with a TXV. Replacement TXV must
be designed for Puron (R-410A).
• Do not use an R-22 TXV.
• Never open system to atmosphere while it is under a vacuum.
• When system must be opened for service, break vacuum with
dry nitrogen and replace filter driers.
• Do not vent Puron (R-410A) into the atmosphere.
• Do not use capillary tube indoor coils.
• Observe all warnings, cautions and bold text.