Install Instructions

85
IM-PR 566442 1114 (Design Manual)
Figure 3-8. Rotating horizontal desiccant bed. Trays
containing dry desiccant are slowly rotated between
process and reactivation airstreams. Although care
must be taken to avoid leakage between moist
and dry airstreams, the design is inexpensive to
produce.
26
3.6.4 Cooling control strategies
Controls for radiant cooling systems should
be specified with the objectives of reducing
condensation potential, providing for occupant
comfort and optimizing energy efficiency and
equipment performance.
Condensation control for a radiant cooled
slab is accomplished by controlling the space
dewpoint through latent cooling and by ensuring
that the slab surface temperature does not fall
below the space dewpoint. To do this, exhaust
high-humidity loads at their source, provide for
dehumidification of air (latent cooling) and precise
dewpoint control through supplementary cooling
equipment, and install controls to keep the supply
water temperature above the space dewpoint
temperature by mixing or by bypassing the chiller
when necessary.
Various control strategies for a sensible radiant
cooling system are listed in Table 3-9.
Control Scenario Advantages Disadvantages
Fixed-speed pump, fixed water
temp
Simple, reliable
Does not maximize energy
efficiency
Variable-speed pump, fixed
water temperature
Reduces pumping energy
requirements by maintaining a
constant system pressure as
zones open or close
Does not maximize central plant
efficiency
Fixed-speed pumps, variable
water temperature
Improves efficiency of central
plant by letting it operate over a
broader range of temperatures
Does not maximize pumping
efficiency
Variable-speed pumps, variable
water temperature
Can minimize pumping energy
requirements and maximize
central plant efficiency
Can have higher first costs than
other scenarios
26 . Harriman III, Lewis G. 1989. The Dehumidification Handbook (Second Edition) p. 36
Table 3-9