No access to evaporator/air handler

[John Arnold]

130 year old home with a very cramped "attic" space where they put the high velocity AC evaporator and air handler. This return in the second floor hall ceiling is the only possible access to the equipment, other than cutting a big hole in the ceiling.
And the crazy part is that there is a forced air furnace, not a boiler, in the basement. Why would they do this instead of using the existing ductwork and adding the evaporator at the furnace??

28368

[Raymond Wand]

Likely due to smaller original supply and lack of return air ducts on 2 nd floor. A/C air is heavy and due to undersized ducts the basement heating unit cannot force enough air to second floor.

[Joe Funderburk]

"R807.1 Attic access. Buildings with combustible ceiling or
roof construction shall have an attic access opening to attic
areas that exceed 30 square feet (2.8 m2) and have a vertical
height of 30 inches (762 mm) or greater. The vertical height
shall be measured from the top of the ceiling framing members
to the underside of the roof framing members.

The rough-framed opening shall not be less than 22 inches
by 30 inches (559 mm by 762 mm) and shall be located in a
hallway or other readily accessible location. When located in a
wall, the opening shall be a minimum of 22 inches wide by 30
inches high...."
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"M1305.1 Appliance access for inspection service, repair and
replacement. Appliances shall be accessible for inspection, service,
repair and replacement without removing permanent construction,
other appliances, or any other piping or ducts not
connected to the appliance being inspected, serviced, repaired
or replaced. A level working space at least 30 inches deep and 30
inches wide (762 mm by 762 mm) shall be provided in front of
the control side to service an appliance."

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"M1305.1.3 Appliances in attics. Attics containing appliances
shall be provided with an opening and a clear and unobstructed
passageway large enough to allow removal of the largest appliance,
but not less than 30 inches (762 mm) high and 22 inches
(559 mm) wide and not more than 20 feet (6096 mm) long measured
along the centerline of the passageway from the opening
to the appliance. The passageway shall have continuous solid
flooring in accordance with Chapter 5 not less than 24 inches
(610 mm) wide. A level service space at least 30 inches (762
mm) deep and 30 inches (762 mm) wide shall be present along
all sides of the appliance where access is required. The clear
access opening dimensions shall be a minimum of 20 inches by
30 inches (508 mm by 762 mm), and large enough to allow
removal of the largest appliance.

Exceptions:

1. The passageway and level service space are not
required where the appliance can be serviced and
removed through the required opening.

2. Where the passageway is unobstructed and not less
than 6 feet (1829 mm) high and 22 inches (559 mm)
wide for its entire length, the passageway shall be not
more than 50 feet (15 250 mm) long.”

“Code Commentary: There is not always sufficient room for mechanical
equipment and appliances to be installed in spaces
such as basements, alcoves, utility rooms and furnace
rooms. In an effort to save floor space or simplify an installation,
designers often locate appliances and mechanical
equipment on roofs, in attics or in similar remote
locations. Access to appliances and equipment
could be difficult because of…or the lack of a
walking surface, such as might occur
in an attic or similar space with exposed ceiling
joists. This section requires a suitable access opening,
passageway and workspace that will allow reasonably
easy access without endangering the service person
(see Commentary Figure M1305.1.3). The longer the
attic passageway, the more the service person will be
exposed to extreme temperatures and the risk of injury.
The attic access opening (typically a scuttle) must
be large enough to allow the largest appliance in the
attic to pass through such opening. For example, if an
attic furnace is the largest appliance, the furnace itself
should be able to be removed from the attic without
having to disassemble the furnace. Of course, it is understood
that ducts, plenums, cooling coil cabinets
and other attachments might have to be disconnected
from the furnace before removal is possible.

The first exception allows the passageway and level
service space to be eliminated if the technician can
reach the appliance through the access opening without
having to step into the attic. The second exception
allows the length of the passageway to be extended to
50 feet (15 250 mm) if there is at least 6 feet (1829
mm) of clear headroom for the entire length of the passageway.
This is allowed because there is less danger
of lengthy exposure to extreme temperatures if the
service personnel can walk erect and unimpeded to
the equipment rather than crawling.”