McQuay PDAC Installation Manual
Installation & Maintenance Data IM 376-2
Incremental® System
Information For Owners & Operators
Group: PTAC
Part No.: 106018502
Date: November 2003
©2003 McQuay International
®
Introduction
The Incremental system is a perimeter system of complete fourseason air conditioning. As such, it conditions the exterior spaces
of multi-room, multi-story buildings-spaces usually within 25 to
35 feet of an outside wall.
The Incremental system is compatible with any core or interior system, as sometimes required to supplement the perimeter
system.
Each Incremental system consists of two or more of the
following basic elements:
1. A conventional central steam or hot water heating installa-
tion, but with radiators omitted or removed from the spaces to
be air conditioned. (Not required for all-electric systems.)
2. An adequate electrical wiring system of conventional
design. In the case of existing buildings, this usually
requires rewiring.
3. A unique, noiseless type of personal four-season air condi-
tioner called the Incremental conditioner. This usually occu-
pies less floor space than the radiator it replaces.
4. Optionally, a unique system of control that prevents wasteful
operation of the equipment, yet provides air conditioning to
each occupant whenever desired.
Designer’s Concept
The Incremental system is intended for both existing and new
structures. The smallest installation has but one Incremental conditioner. The largest may have well over 1000. The system is called
"incremental" because:
1. In providing health, comfort and personal efficiency to build-
ing occupants, it treats them not in groups, but rather in
increments consisting of each person, as an individual.
2. It may conveniently be installed over a period of years, as
occupants desire or money permits, in increments of one
suite, one floor, or one wing at a time-at no higher total cost
than doing the entire building at one time. This is not so with
other systems.
3. It may initially be installed for all functions of air conditioning,
except summer cooling, at a saving in first cost. When wanted,
the cooling increment may be added, in a few minutes, by a
regular building employee.
Since there is no such thing as regimented personal comfort,
it is contemplated that the principal occupant of each room or
office space should exercise control over his Incremental conditioner, and thus over his indoor environment.
User Instructions
Incremental conditioners are simple to operate. Nevertheless,
instructions, “How to Operate Your Incremental Air Conditioning,”
are taped to each room cabinet at time of shipment.
The foregoing items are for systems with standard equipment,
using steam or hot water for heating. Instructions are also
available for the even simpler all-electric systems. On request,
special instructions will be prepared for users of custom-built,
nonstandard equipment.
Complaints will be eliminated if the equipment is actually demonstrated to users who are unfamiliar with it. In any case, new
users should be encouraged to read the detailed operating
instructions, or, at the very least, the instructions sticker.
Owner and Operator Instructions
In addition to normal operation of the equipment as described in
the user instructions, the building owner or operator is normally
responsible for:
1. Filter Cleaning or Replacement—Air filters must be cleaned
or replaced (depending on the type) at regular intervals. Twice
a year is adequate in some locations. Once a month or even
twice a month is essential in others. It all depends on the
amount of dirt in the atmosphere, lint from linens and rugs,
and the usage of the equipment. Malfunctioning of the equipment will result if filters are not kept clean.
2. Operation of the Central Heating Plant—This requires no
further explanation than to say that, as against other systems,
the Incremental system normally saves from 10% to 25% of
the heat required for comfort. That is because it has “a thermostat in every room.” And, because this is true, it is recommended: (a) that the central heat be turned on earlier in the
fall than are other systems, and (b) that the central heat be
turned off later in the spring than are other systems.
Following this recommendation pleases those occupants who
may be classified as the “too colds.” And, because this system
uses only as much heat as needed to keep these few people
comfortable, it gives them this added luxury at very little
extra cost.
3. The Concealed Ventilation Switch—Most Incremental equip-
ment has an electrically actuated damper to control the intro-
duction of outdoor ventilating air, under positive pressure.
Normally this damper functions automatically, being open
when the equipment is operating and closed when it is stopped.
A control switch is, however, provided in the damper circuit. It
is in a concealed location and not mentioned in the user
instructions.
The concealed damper control has been incorporated in
Incremental equipment at the request of experienced building
owners and operators. Its purpose is to save fuel during the heating season. By moving the damper switch to closed in the fall
and returning it to automatic operation in spring, fuel will be
saved, because less cold outside air will enter the conditioned
space.
4. Fan Motor Oiling—More motors are ruined by over-oiling than
by under-oiling. Incremental equipment is normally supplied
with motors having “permanently” oiled bearings. All fan mo-
tors are permanently lubricated by the manufacturer. They do
not require further oiling.
5. Helpful Hints—Every autumn inspect the heating section,
clean if required and test-check all controls. Every spring
inspect the cooling chassis, clean if required and test-check
the controls. If the compressor seems noisy, it should quiet
down after a few days of operating during which time refriger-
ant and oil in the circuit will separate properly.
In the case of cooperatively owned apartment buildings, it is
recommended that the management group arrange for one (1)
source for servicing the air conditioning equipment in all apartments. This is usually more satisfactory and less costly to the
individual owners than if each goes his own way.
IM 376 / Page 2 of 4 (Rev. 11/03)
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