26
Centrifugal Chillers
D-EIMWC00804-14EN
Oil Heater
The oil sump is equipped with an immersion heater that is installed in a tube so that it can be
removed without disturbing the oil.
Relief Valves
As a safety precaution and to meet code
requirements, each chiller is equipped with
pressure relief valves located on the condenser,
evaporator, and oil sump vessel for the purpose
of relieving excessive refrigerant pressure
(caused by equipment malfunction, fire, etc.) to
the atmosphere. Most codes require that relief
valves be vented to the outside of a building,
and this is a desirable practice for all
installations. Relief piping connections to the
relief valves must have flexible connectors.
Note
:
Remove plastic shipping plugs (if
installed) from the inside of the valves prior
to making pipe connections. Whenever
vent piping is installed, the lines must be
run in accordance with local code
requirements; where local codes do not
apply, the latest issue of ANSI/ASHRAE
Standard 15 code recommendations must
be followed.
Condensers have two relief valves as a set with a three-way valve separating the two valves
(large condensers will have two such sets). One valve remains active at all times and the second
valve acts as a standby.
Figure 13, Condenser 3-Way Valve
Refrigerant Vent Piping
Relief valve connection sizes are one-inch FPT and are in the quantity shown in Table 2 and
Table 3 on page 21. Twin relief valves mounted on a transfer valve are used on the condenser so
that one relief valve can be shut off and removed, leaving the other in operation. Only one of the
two is in operation at any time. Where four valves are shown in the table, they consist of two
valves, each mounted on two transfer valves. Only two relief valves of the four are active at any
time.
