17
Unitary Air Handler DX and Hydronic Series
6720220327
Revised 11-11 Subject to change without prior notice
blower speed can be changed to a lower speed to reduce
air flow. (Refer to ECM motor interface board section in
this manual and the Blower Performance Table in the
Technical Data section at the end of this manual.)
PIPING
Supply and return piping must be as large as the
unit connections on the heat pump (larger on long
runs). Never use flexible hoses of a smaller inside
diameter than that of the fluid connections on the
unit. Bosch condensing section units are supplied
with either a copper or optional cupro-nickel
condenser. Copper is adequate for ground water
that is not high in mineral content. Should your well
driller express concern regarding the quality of the
well water available or should any known hazards
exist in your area, we recommend proper testing to
assure the well water quality is suitable for use with
water source equipment. In conditions anticipating
moderate scale formation or in brackish water a
cupro-nickel heat exchanger is recommended.
Both the supply and discharge water lines will sweat if
subjected to low water temperature. These lines should
be insulated to prevent damage from condensation.
All manual flow valves used in the system must be ball
valves. Globe and gate valves must not be used due to
high pressure drop and poor throttling characteristics.
Never exceed the recommended water flow rates as
serious damage or erosion of the water to refrigerant
heat exchanger could occur. Refer to the Technical
Data section at the end of this manual to determine the
recommended water flow rate for specific conditions.
Always check carefully for water leaks and repair
appropriately. Units are equipped with female pipe
thread fittings. Consult the specification sheets of
the paired condensing section for sizes. Teflon tape
sealer should be used when connecting water
piping connections to the units to insure against
leaks and possible heat exchanger fouling. Do not
over-tighten the connections. Flexible hoses should
be used between the unit and the rigid system to
avoid possible vibration. Ball valves should be
installed in the supply and return lines for unit
isolation and unit water flow balancing.
DX REfRIGERANt PIPING
Air handlers with DX type evaporator coils require
liquid and suction piping sized in accordance with
condensing unit manufacturer’s recommendations.
The evaporator coils have sweat copper connections.
Refrigerant lines should be soldered with silver solder
or other high temperature brazing alloy.
The suction line must be insulated for satisfactory
operation to avoid creating condensation. If the
condensing unit is located over the evaporator coil,
then oil traps are required at equal intervals along the
suction line.
Horizontal suction line runs should be sloped 1" every
20' towards the condensing unit. The manufacturer
recommends that dry nitrogen be flowed through the
refrigerant lines during the soldering operation.
Liquid line is capped.
• Install 1 oil trap for a height difference of 15 ft to
25 ft (4.6 m to 7.6 m) between condensing
section and air handler.
• Install 2 oil traps for a height difference of 26 ft to
50 ft (7.9 m to 15.2 m) between condensing
section and air handler.
• Install 3 oil traps for a height difference of 51 ft to
100 ft (15.5 m to 30.5 m) between condensing
section and air handler.
It is not recommended that a height difference of
more than 100 ft exists between the two units.
figure 8: Evaporator below Condenser Piping
Piping
