Trane EXWA, WPWD, GSWD Installation, Hazardous Voltage, Note The wires must be moved from one low

Installation

Changing Freezestat or Low Pres- sure Cutout Switches (WPWD/GSWD models ONLY) Each unit has two factory installed low pressure cutout switches and one freezestat. Only one of the low pres- sure cutout switches is connected to the 24 volt control circuit, dependent on which freezestat is being used (i.e. 35°F or 20°F). Both the freezestat and the low pressure cutout are in the lock- out relay circuit. The freezestat moni- tors the temperature of the water leaving the source and load side wa- ter-to-refrigerant heat exchangers, protecting the heat exchanger from fluid freeze up. The low pressure cut- out monitors the suction pressure of the compressor to protect the com- pressor from liquid floodback or oper- ating under loss of charge conditions.

Units can be ordered from the factory with either the 35°F or 20°F freezestat option. The 20°F freezestat is ONLY used on closed loop systems with an- tifreeze solution. The 35°F freezestat is used on all other systems. The type of freezestat on a unit can be determined from the appropriate digit in the model number. Digit 11 and/or 12 with a se- lection of 1 is a 35°F freezestat, where- as selection 2 is a 20°F freezestat.

What Freezestat Should Be Applied?

As previously mentioned, every unit is shipped from the factory with two low pressure cutouts installed in the refrig- erant circuit. One of the low pressure cutouts disables the compressor at 35 psig, while the other disables the com- pressor at 7 psig. The 35 psig cutout is used with the 35°F freezestat, while the 7 psig cutout is used with the 20°F freezestat.

Occasionally it will be necessary to change the freezestat in the field. Ex- amples of when this change-out is necessary include:

(1)A unit with a 35°F freezestat is go- ing to be put on a closed loop system with antifreeze. By definition, the unit requires a 20°F freezestat.

(2)A unit with a 20°F freezestat is go- ing to be put on an open well system or a closed loop system with NO anti- freeze solution. By definition, the unit must have a 35°F freezestat installed prior to operation.

The best time to install the freezestat/ low pressure cutout is prior to install- ing the unit. The freezestat is easily ac- cessible from the top service door.

WARNING

Hazardous Voltage!

Disconnect all electric power, in- cluding remote disconnects be- fore servicing. Follow proper lockout/tagout procedures to en- sure the power can not be inad- vertently energized. Failure to disconnect power before servic- ing could result in death or seri- ous injury.

Changing a Freezestat and Low Pressure Cutout

The freezestat is located in the top of the source-side water-to-refrigerant heat exchanger leaving water line. The freezestat is located in the twelve o’clock position. The capillary tube is inserted into the well approximately 8- inches. Remove the existing freezestat and replace it with the new freezestat.

Note: The wires must be moved from one low

pressure cutout to the other.

The low pres-

sure cutouts are located in the insu-

lated re- frigerant lines. The high pressure cutout is locat- ed in the un-insulated compressor dis- charge line and is the

only pressure cutout located

in this line. Change the wires from

the old low pressure cutout to the new low pressure cutout.

Identifying the Low Pressure Cutouts The 7 psig low pressure cutout is used with a 20°F freezestat. It is installed in the insulated line and is in the piping tee going to the external schrader port. The 35 psig low pressure cutout is used with a 35°F freezestat. It is in- stalled in the insulated line and is not connected to any fittings.

The 395 psig high press cutout is in- stalled in the un-insulated compressor discharge line. It is the only cutout lo- cated in this line. Further, it is connect- ed to an external schrader port.

If the low pressure cutout is not changed when the freezestat is changed, problems will occur. If the 35 psig low pressure cutout is connected to a 20°F freezestat, the unit will go out repeatedly on the low pressure cutout. If the 7 psig low pressure cutout is used with the 35°F freezestat, no prob- lems will occur as long as the freez- estat is operating normally. However, if the freezestat does fail, the loop wa- ter could freeze before the suction pressure dropped low enough for the 7 psig cutout to take the unit off the line. Also, in a loss of charge situation, the heat exchanger would freeze be- fore the freezestat could take the unit off-line.

Figure 11: Pressure switch location

18 WSHP-SVX02A-EN