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GUIDE SPECIFICATIONS — 542J150,180 (cont)
E. Coils:
1. Standard indoor and outdoor coils shall have copper
or aluminum plate fins mechanically bonded to
seamless internally grooved copper tubes with all
joints brazed.
2. Coils shall be leak tested at 150 psig (1034 kPa) and
pressure tested at 450 psig (3103 kPa).
3. Coils:
a. Copper-fin coils shall be constructed of copper
fins mechanically bonded to copper tubes and
copper tube sheets. Galvanized steel tube sheets
shall not be acceptable. A polymer strip shall pre-
vent coil assembly from contacting the sheet
metal coil pan to minimize potential for galvanic
corrosion between coil and pan. All copper con-
struction shall provide protection in moderate
coastal environments.
b. E-Coated aluminum-fin coils shall have a flexible
epoxy polymer coating uniformly applied to all coil
surface areas without material bridging between
fins. Coating process shall ensure complete coil
encapsulation. Color shall be high gloss black
with gloss — 60 deg of 65 to 90% per ASTM
D523-89. Uniform dry film thickness from 0.8 to
1.2 mil on all surface areas including fin edges.
Superior hardness characteristics of 2H per
ASTM D3363-92A and cross-hatch adhesion of
4B-5B per ASTM D3359-93. Impact resistance
shall be up to 160 in.-lb (ASTM D2794-93).
Humidity and water immersion resistance shall be
up to minimum 1000 and 250 hours respectively
(ASTM D2247-92 and ASTM D870-92). Corro-
sion durability shall be confirmed through testing
to be no less than 1000 hours salt spray per
ASTM B117-90. Coil construction shall be alumi-
num fins mechanically bonded to copper tubes.
c. E-Coated copper-fin coils shall have a flexible
epoxy polymer coating uniformly applied to all coil
surface areas without material bridging between
fins. Coating process shall ensure complete coil
encapsulation. Color shall be high gloss black
with gloss — 60 deg of 65 to 90% per ASTM
D523-89. Uniform dry film thickness from 0.8 to
1.2 mil on all surface areas including fin edges.
Superior hardness characteristics of 2H per
ASTM D3363-92A and cross-hatch adhesion of
4B-5B per ASTM D3359-93. Impact resistance
shall be up to 160 in.-lb (ASTM D2794-93).
Humidity and water immersion resistance shall be
up to minimum 1000 and 250 hours respectively
(ASTM D2247-92 and ASTM D870-92). Corro-
sion durability shall be confirmed through testing
to be no less than 1000 hours salt spray per
ASTM B117-90. Coil construction shall be copper
fins mechanically bonded to copper tubes with
copper tube sheets. Galvanized steel tube sheets
shall not be acceptable. A polymer strip shall pre-
vent coil assembly from contacting sheet metal
coil pan to maintain coating integrity and minimize
corrosion potential between coil and pan.
d. Optional pre-coated aluminum-fin coils shall have
a durable epoxy-phenolic coating to provide pro-
tection in mildly corrosive coastal environments.
Coating shall be applied to the aluminum fin stock
prior to the fin stamping process to create an inert
barrier between the aluminum fin and copper
tube. Epoxy-phenolic barrier shall minimize gal-
vanic action between dissimilar metals.
F. Heating Section:
1. May be equipped with field-installed electric resis-
tance heater(s) of the characteristics shown in the
equipment schedule.
2. Heater elements shall be open wire, adequately
supported and insulated with ceramic bushings.
G. Refrigerant Components:
Refrigerant circuit components shall include:
1. Fixed orifice metering system (Acutrol
TM
device).
2. Refrigerant filter drier.
3. Reversing valve.
4. Service gage connections on suction, discharge, and
liquid lines.
H. Filter Section:
1. Standard filter section shall consist of factory-
installed, low velocity, throwaway 2-in. thick fiber-
glass filters of commercially available sizes.
2. Filter face velocity shall not exceed 320 fpm at nomi-
nal airflows.
3. Filter section should use only one size filter.
4. Filters shall be accessible through an access panel
with “no-tool” removal.
I. Controls and Safeties:
1. Unit Controls:
Unit shall be complete with self-contained low-
voltage control circuit protected by a resettable
circuit breaker on the 24-v transformer side.
2. Safeties:
a. Unit shall incorporate a solid-state compressor
protector which provides anti-cycle reset capabil-
ity at the space thermostat, should any of the
following standard safety devices trip and shut off
compressor.
1) Compressor overtemperature, overcurrent.
2) Loss-of-charge/low-pressure switch.
3) Freeze-protection thermostat, evaporator coil.
4) High-pressure switch.
5) Automatic reset motor thermal overload
protector.
The lockout protection shall be easily discon-
nected at the control board, if necessary.
b. Heating section shall be provided with the follow-
ing minimum protections:
1) High-temperature limit switches.
2) Overcurrent protection.
c. Unit shall incorporate an outdoor coil defrost
system to prevent excessive frost accumulation
during heating duty, and shall be controlled as
follows:
1) Defrost shall be initiated on the basis of time
and coil temperature.
2) A 30/50/90-minute timer shall activate defrost
cycle only if the coil temperature is low enough
to indicate a heavy frost condition.
3) Defrost cycle shall terminate when defrost
thermostats are satisfied and shall have a pos-
itive termination time of 10 minutes.
542J