cross-contamination. Heat exchanger tube core shall be [15] [18] [25] mm
[1/2] [5/8] [1] inch nominal diameter, seamless aluminum or copper tube
with extended surfaces, utilizing wrought aluminum Alloy 3003 or Alloy
5052, temper to suit. Maximum fins per unit length and number of tube rows
shall be as indicated. Tubes shall be fitted with internal capillary wick,
filled with an ASHRAE 15, Group 1 refrigerant working fluid, selected for
system design temperature range, and hermetically sealed. Heat exchanger
frame shall be constructed of not less than 1.6 mm 16 gauge galvanized
steel and fitted with intermediate tube supports, and flange connections.
Tube end-covers and a partition of galvanized steel to separate exhaust and
supply air streams without cross-contamination and in required area ratio
shall be provided. [A drain pan constructed of welded Type 300 series
stainless steel shall be provided.] Heat recovery regulation shall be
provided by [system face and bypass dampers and related control system as
indicated] [interfacing with manufacturer's standard tilt-control mechanism
for summer/winter operation, regulating the supply air temperature and
frost prevention on weather face of exhaust side at temperature indicated].
Coil shall be fitted with pleated flexible connectors.
2.10.4
Dessicant Wheel
Supply and regeneration airstreams shall be counterflow. The dehumidifier
shall be a rotary type designed for continuous operation. The wheel
structure shall be of the extended surface type in the axial flow direction
and the geometry shall provide for laminar flow over the operating range
for minimum air pressure differentials. The dehumidifier shall be complete
with a drive system utilizing a fractional-horsepower electric motor and
speed reducer assembly driving the rotor. A slack-side tensioner shall be
included for automatic take-up for belt-driven wheels. The desiccant
material shall be an adsorbing type. The desiccant material shall be
applied to the wheel such that the entire surface is active as a desiccant
and the desiccant material does not degrade or detach from the surface of
the wheel. The wheel shall be fitted with full-face, low-friction contact
seals on both sides to prevent cross leakage. The rotary structure shall
have underheat, overheat and rotation fault circuitry. The wheel assembly
shall be warranted for a minimum of five years.
2.10.5
Plate Heat Exchanger
Energy recovery ventilator unit shall be factory-fabricated for indoor
installation, consisting of a flat plate cross-flow heat exchanger, cooling
coil, supply air fan and motor and exhaust air fan and motor. Casing shall
be 1 mm 20 gauge G90, galvanized steel, double wall construction with 25 mm
one inch insulation. Heat exchanger core shall be fibrous desiccant
cross-flow type capable of easy removal from the unit.
2.11
FACTORY PAINTING
Units which are not of galvanized construction according to ASTM A 123/A
123M or ASTM A 924/A 924M shall be factory painted with a corrosion
resisting paint finish. Internal and external ferrous metal surfaces shall
be cleaned, phosphatized and coated with a paint finish which has been
tested according to ASTM B 117, ASTM D 1654, and ASTM D 3359. Evidence of
satisfactory paint performance for a minimum of 125 hours for units to be
installed indoors and 500 hours for units to be installed outdoors shall be
submitted. Rating of failure at the scribe mark shall be not less than 6,
average creepage not greater than 3 mm 1/8 inch. Rating of the inscribed
area shall not be less than 10, no failure. On units constructed of
galvanized steel that have been welded, exterior surfaces of welds or welds
SECTION 15895
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