Condensate Drain; Duct System - Bosch DX Series Installation And Maintenance Manual

16 Unitary Air Handler DX and Hydronic Series
unit is used with this air handler, use a thermostat with
isolating contacts to prevent inter-connection of two
separate Class 2 circuits (RC terminal is used for the
condensing section unit and RH terminal is used for the
air handler. The jumper between RC and RH must be
removed). Set thermostat heat anticipator at 0.15
amps for units 12KW or smaller, set at .30 amps for 15
KW and larger.
The labeled terminal block in the remote
condensing section or water-to-water unit will
identify the required connections.

CONDENSAtE DRAIN

The air handler "A" coil drain pan has two ¾" NPT
female primary and two secondary connections (left
or right hand). Horizontal pan has two ¾" NPT female,
one primary and one secondary. Piping from each
fitting used is to have 1-1/2 minimum trap and each
run in such a manner as to provide enough slope for
adequate drainage to a visible area. A drain line must
be connected to the heat pump and pitched away
from the unit a minimum of 1/8" per foot to allow the
condensate to flow away from the unit.
This connection must be in conformance with local
plumbing codes. A trap must be installed in the
condensate line to insure free condensate flow.
(Heat Pumps are not internally trapped). A vertical
air vent is sometimes required to avoid air pockets.
(See Figure 6). The length of the trap depends on
the amount of positive or negative pressure on the
drain pan. A second trap must not be included.
The horizontal unit should be pitched
approximately 1/4" towards the drain in both
directions, to facilitate condensate removal. (See
Figure 7)
figure 6
6720220327
figure 7

DUCt SYStEM

A supply air outlet collar is provided on all units to
facilitate duct connections. Refer to the
dimensional sheet at the beginning of this manual
for physical dimensions of the collar.
A flexible connector is recommended for supply air
duct connections on metal duct systems. All metal
ducting should be insulated with a minimum of one
inch duct insulation to avoid heat loss or gain and
prevent condensate forming during the cooling
operation. Applications utilizing uninsulated duct
work are not recommended as the unit's performance
will be adversely affected. Do not connect discharge
ducts directly to the blower outlet. The factory
provided air filter must be removed when using a filter
back return air grill. The factory filter should be left in
place on a free return system.
If the unit will be installed in a new installation
which includes new duct work, the installation
should be designed using current ASHRAE
procedures for duct sizing. If the unit is to be
connected to existing ductwork, a check should be
made to assure that the duct system has the
capacity to handle the air required for the unit
application. If the duct system is too small, larger
ductwork should be installed. Check for existing
leaks and repair.
The duct system and all diffusers should be sized to
handle the designed air flow quietly. To maximize sound
attenuation of the unit blower, the supply and return air
plenums should be insulated. There should be no direct
straight air path thru the return air grille into the heat
pump. The return air inlet to the heat pump must have at
least one 90 degree turn away from the space return air
grille. If air noise or excessive air flow are a problem, the
Subject to change without prior notice
Condensate Drain
1/4"
Revised 11-11