340
Heating-Ventilating-Cooling: Generic Design Options
342
GENERIC DESIGN OPTIONS
The following are the subsystem options for HVC. A fuller discussion of
these choices is given in Section 724.1.
342.1
SUPPLY SYSTEMS
The two major alternatives for supply are low- or medium-pressure
terminal-reheat, and the dual-duct mixing-box systems. The only
qualification is that close humidity control required for certain areas of the
hospital would be difficult to achieve with a dual-duct system, unless total
air cooling and humidifying is employed.
Where climatic conditions require it, a mixed system which combines hot
water convectors for building perimeter auxiliary heating with a single-or
dual-duct system for heating and cooling, is a prime variation.
342.2
RETURN AND EXHAUST SYSTEMS
The system must be capable of handling from 25 to 100 percent outside
air. Both return and general exhaust can be extracted through the service
zone by either duct or plenum. In the latter case the effects of system
leakage and fire hazard need to be taken into account. The fans to the
system would be placed in the service bay mechanical room. Special
exhaust ducts will be required variously in each service module ducted
through the service bay to fans on the roof. They will handle a range of
conditions from sets of individual toilets to large areas such as isolation
suites.
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