Water Supply/Return Connections; Steam Connections; Direct Expansion (Dx) Refrigerant Piping; Test And Insulate - Carrier 42CA Installation, Start-Up And Service Instructions Manual

Drain Pan
"P" trap as required
Drain
Clamp
2" Minimum
"P" Trap
Fig. 39 — "P" Trap Minimum Configuration
WATER SUPPLY/RETURN CONNECTIONS — In-
stall piping in accordance with all applicable codes. Position
valves over the drain pan. Be sure valves are in proper operat-
ing position and are easily accessible for adjustment, refer to
Fig. 34-37.
If coil and valve package connections will be made with a
solder joint, care should be taken to ensure that the components
in the valve package are not subjected to high temperatures,
which may damage seals or other materials. Protect all valve
accessories with wet or damp rag wrapped around the body
during soldering / brazing process. See Fig. 40. Many 2-posi-
tion electric control valves are provided with a manual operat-
ing lever. This lever should be in the OPEN position during all
soldering operations.
If coil connection is made with a union, the coil side of the
union must be prevented from turning (it must be backed up)
during tightening. Refer to Fig. 34-37 for common valve pack-
ages.
The supply and return connections are marked and color
coded on the coil stub out and valve package. Supply side is
marked as 'S' and return side is marked as 'R.' A blue letter indi-
cates cooling side and a red letter indicates heating side. In case
of field-installed valves and piping, install chilled water valve
components in a way that any condensate dripping or sweating
caused is contained in the extended drain pan or auxiliary drain
or drip lip (optional). Optional drip lip is field installed and
may be packaged separately from the unit.
CAUTION
DO NOT OVERTIGHTEN! Overtightening will distort
(egg shape) the union seal surface and destroy the union.
NOTE: The project specifications for system pressure, pres-
sure drop limitations, and flow rate should be checked prior to
selection of specific components or the valve package size.
STEAM CONNECTIONS — On units with steam heating
coils, the maximum steam pressure applied to the unit should
Unit
NOTE: Field trim
Wall
to prevent kinking.
Drain
Clamp
never exceed 10 psig. However, when steam is used on a 4-
pipe application system with 1-row and 2-row coils the maxi-
mum steam pressure should never exceed 5 psig (suitable for
only low pressure steam).
Do not drain the steam mains or take-off through the coils.
Drain the mains ahead of the coils through a steam trap to the
return line. Overhead returns require 1 psig of pressure at the
steam trap discharge for each 2 ft elevation to ensure continu-
ous condensate removal.
Proper steam trap selection and installation is necessary. As
a guideline in creating a steam trap locate the steam trap dis-
charge at least 12 in. below the condensate return connection.
This provides sufficient hydrostatic head pressure to overcome
trap losses and ensure complete condensate removal.
DIRECT EXPANSION (DX) REFRIGERANT PIPING —
Use the condensing unit manufacturer's recommended line
sizes and requirements. Suction line must be insulated for cor-
rect operation. Use refrigerant-grade copper lines only. The
unit is not applied as a heat pump.
Thermostatic expansion valve (TXV) and sensing bulb are
factory-installed on units when DX coil option is chosen with
distributor and TXV. The TXV is equipped with an external
equalizer connection to allow pressures to equalize when the
compressor is shut off. The equalizer piping connection must
be made in the field.
NOTE: If a hot water coil is used in the reheat position, a field-
supplied freezestat must be installed to protect the coil.
TEST AND INSULATE — When all joints are complete,
perform hydrostatic test for leaks. Vent all coils at this time.
Check interior unit piping for signs of leakage from shipping
damage or mishandling. If leaks are found, notify your Carrier
representative before initiating any repairs. Release trapped air
from system (Refer to "Step 7 — Make Final Preparations" on
page 48.).
Never pressurize any equipment beyond specific test pres-
sure. Always pressure test with an inert fluid or gas, such as
clear water or dry nitrogen to avoid possible damage or injury
in the event of a leak or component failure during testing.
All water coils must be protected from freezing after initial
filling with water. Even if system is drained, unit coils may
still have enough water to cause damage when exposed to
temperatures below freezing.
Following the hydrostatic test, insulate all piping to prevent
sweating.
To ensure compliance with building codes, restore the struc-
ture's original fire resistance rating by sealing all holes with
material carrying the same fire rating as the structure.
41
CAUTION