88
3. Standard Heat Exchanger construction
a. Heat exchanger shall be of the tubular--section type constructed of a minimum of 20--gauge steel coated with a
nominal 1.2 mil aluminum--silicone alloy for corrosion resistance.
b. Burners shall be of the in--shot type constructed of aluminum--coat ed steel.
c. Burners shall incorporate orifices for rated heat output up to 2000 ft (610m) elevation. Additional accessory
kits may be required for applications above 2000 ft (610m) elevation, depending on local gas supply condi-
tions.
d. Each heat exchanger tube shall contain multiple dimples for increased heating effectiveness.
4. Optional Stainless Steel Heat E xchanger construction
a. Use energy saving, direct--spark ignition system.
b. Use a redundant main gas valve.
c. Burners shall be of the in--shot type constructed of aluminum--coated steel.
d. All gas piping shall enter the unit cabinet at a single location on side of unit (horizontal pl ane).
e. The optional stai nless steel heat exchanger shall be of the tubular--section type, constructed of a minimum of
20--gauge type 409 stainless stee l.
f. Type 409 stainless steel shall be used in heat exchanger tubes and vestibule plate.
g. Complete stainless steel heat exchanger allows for greater application flexibility.
5. Optional Low NO
x
Heat Exchanger construction
a. Low NO
x
reduction shall be provided to reduce nitrous oxide emissions to meet California’s Air Quality Man-
agement District (SCAQMD) low--NO
x
emissions requirement of 40 nanograms per joule or less.
b. Primary tubes and vestibule plates on low NO
x
units shall be 409 stainless steel. Other components shall be
aluminized steel.
6. Induced draft combustion motor and blower
a. Shall be a direct--drive, single inlet, forward --curved centrifugal type.
b. Shall be made from steel with a corrosion--resistant finish.
c. Shall have permanently lubricated sealed bearings.
d. Shall have inherent thermal overl oad protection.
e. Shall have an automatic reset feature.
23 81 19.13.J. Coils
1. Standard Aluminum Fin -- Copper Tube Coils:
a. Standard evaporator and condenser coils shall have aluminum lanced plate fins mechanica lly bonded to seam-
less internally grooved copper tubes with all j oints brazed.
b. Evaporator coils shall be leak tested to 150 psig, pressure tested to 450 psig, and qualified to UL 1995 burst
test at 1775 psig.
c. Condenser coils shal l be leak tested to 150 psig, pre ssure tested to 650 psig, and qualifi ed to UL 1995 burst
test at 1980 psig.
2. Optional Pre--coa ted aluminum--fin condenser coils:
a. Shall have a durable epoxy--phenolic coating to provide protection in mildly corrosive coastal e nvironments.
b. Coating shall be applied to the a luminum fi n stock prior to the fin stamping process to create an inert barri er
betwee n the alumi num fin and copper tube.
c. Epoxy--phenolic barrier shall minimize galvanic action between dissimilar metals.
3. Optional Copper--fin evaporat or and condenser coils:
a. Shall be constructed of copper fins mechanically bonded to copper tube s and copper tube sheets.
b. Galvanized steel tube sheets shall not be acceptable.
c. A polymer strip shall prevent coil assembly from contacting the sheet metal coil pan to minimize potential for
galvanic corrosion between coil and pan.
4. Optional E--coated aluminum--fin evaporator and condenser coils:
a. Shall have a flexible epoxy polymer coating uniformly applie d to all coil surface areas without material
bridging between fins.
b. Coating process shall ensure complete coil encapsulation of tubes, fins and headers.
c. Color shall be high gloss black with gloss per ASTM D523--89.
d. Uniform dry film thickness from 0.8 to 1.2 mil on all surface areas including fin edges.
e. Superior hardness characteristics of 2H per ASTM D3363--92A and cross--hatch adhesion of 4B--5B per ASTM
D3359--93.
f. Impact resistance shall be up to 160 in.--lb (ASTM D2794--93).
580J
To Next Page
Loading...
Need help?
General
