boiler is required, the designer should discuss this
with the manufacturer and investigate the
possibility of modulating control of regeneration
heat (which will be simpler to obtain with an
external, rather than internal, heat source for
regeneration).
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The boiler shall be a gas-fired water heater suitable for delivering fluid
temperatures of 99-104 degrees C 210-220 degrees F. It shall have a copper
tube exchanger and cast iron wet walls. It shall be complete with all
controls, including an automatic gas valve, automatic pilot spark ignition
system, power draft inducer, supply water control temperature sensor, and
suitable safety controls. The hydronic system shall include properly sized
diaphragm type expansion tank. Diaphragm shall be flexible butyl securely
attached to inner tank wall. Maximum allowable working pressure shall be
at least 791 kPa 100 psig, and 116 degrees C 240 degrees F temperature.
2.6.8
Circulating Pumps (Solid Desiccant System)
Evaporative cooling pump shall be a submersible pump with a hooded intake,
polypropylene screen, and thermal overload protection. Boiler pump shall
be an in-line close coupled single stage centrifugal.
2.6.9
Refrigeration Section (Solid Desiccant System)
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NOTE: The addition or elimination of the
refrigeration section to a rotary wheel desiccant
should not hinder the designer from selecting
additional refrigeration equipment downstream or
upstream (pre-cooling coil) of the desiccant unit.
The designer can choose this option, but should view
the desiccant system as part of the total air
delivery system.
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The refrigeration loop shall be integral to the unit, and factory charged.
The condenser section shall provide the heat required to regenerate the
desiccant rotor, and the evaporator section shall provide additional
cooling/dehumidification. Refrigerants shall be one of the
hydrocholrofluorocarbon or hydrofluorocarbon gases. Refrigerants shall
have number designations and safety classifications in accordance with
ASHRAE 34. Refrigerants shall meet the requirements of ARI 700 as a
minimum. Refrigerants shall have an Ozone Depletion Potential (ODP) of
less than or equal to 0.05 and shall be in compliance with EPA regulations.
The unit shall be factory leak tested and dehydrated, as specified in
Section [15181 CHILLED, CHILLED-HOT, AND CONDENSER WATER PIPING SYSTEMS] [
15182 REFRIGERANT PIPING] [or] [Section 15700A UNITARY HEATING AND COOLING
EQUIPMENT].
2.6.10
Conditioner unit (Liquid Desiccant System)
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NOTE: Lithium chloride salt solution is now being
used in liquid desiccant systems. If another
solution is to be used, the designer must edit those
parts that make reference to lithium chloride
solution to reflect the properties of the solution
SECTION 15500A
Page 16
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