AAON RZ Series, Installation Operation & Maintenance

Page: 46 / 112

46
Back Draft Damper Setup
The counter balance is shipped loose and may
need to be installed during start-up on some
applications. Not all applications will require
the use of the counter balance on the back
draft dampers. If the unit is equipped with
back draft dampers on the supply fan, start
the fans without the counter balance and
observe the operation of the back draft
dampers. If the back draft dampers do not
open completely, then the counter balance
can be installed to assist with the opening of
the back draft dampers. Install the counter
balance in the horizontal position when the
back draft dampers are held closed (see
Figure
24 ).
The back draft damper will remain open with
no back pressure on the damper. The damper
will close completely when back pressure is
applied.
Figure 24 - Closed Back Draft Damper
Figure 25 - Open Back Draft Damper
Adjusting Refrigerant Charge
Adjusting the charge of a system in the field
must be based on determination of liquid sub-
cooling and evaporator superheat. On a
system with a TXV liquid sub-cooling is
more representative of the charge than
evaporator superheat but both measurements
must be taken.
Before Charging
Unit being charged must be at or near full
load conditions before adjusting the charge.
Units equipped with hot gas reheat must be
charged with the hot gas reheat valves closed
while the unit is in cooling mode to get the
proper charge. After charging, operate unit in
The Clean Air Act of 1990 bans the
intentional
venting of refrigerant
(CFC’s and HCFC’s) as of July 1,
1992. Approved methods of recovery,
recycling or reclaiming must be
followed. Fines and/or incarceration
may be levied for non-compliance.
CAUTION