Accessories - Z-300

These accessories are frequently used with the Comfort System™ zone control. They offer additional protection for the heating and cooling equipment.
 

FS-38 Low Limit (Suction Line Freeze Stat)

If the suction line temperature drops below 38º F, the compressor will cycle off and remain off until the suction line temperature rises 12º F. The low limit stat should be mounted on the suction line near the evaporator coil and wrapped with insulating tape. The low limit stat should be wired to the two (2) zone panel terminals marked “LL”. The jumper must be removed before connecting the wires.

High Limits

The HL-170 and the HL-170-HP should be located on the discharge plenum or duct ahead of all zone dampers. The high limit stat should be wired to the two (2) zone panel terminals marked “HL”. The jumper must be removed before connecting the wires.

HL-170 (For Gas or Electric Furnaces)

If the discharge temperature rises above 170º F, the furnace will cycle off and remain off until the discharge temperature drops 40º F.

HL-170-HP (For Heat Pumps)

If the discharge temperature rises above 135º F, the heat pump and auxiliary heat will cycle off and remain off until the discharge temperature drops 40º F. This limit is adjustable from 135º to 170º F (factory set at 135º F).

TD-5 Short Cycle Timer (delay on break)

If the condensing unit is not equipped with short cycle protection, a TD-5 short cycle timer should be installed. It can be located either at the condensing unit or at the furnace. The TD-5 should be wired in series with the “Y” wire (cooling control circuit). Short cycle protection is especially important for HVAC systems with zone control, since it is possible for the compressor to be cycled off by one zone and immediately cycled back on by another.

TD-17 Staging Timer (delay on make)

When using two-stage equipment, a TD-17 adjustable timer should be installed to control second stage heating and / or cooling. The timer should be located at the HVAC equipment. Connect one of the timer terminals to “W1” and the other to “W2”, and / or “Y1” and “Y2” of the equipment terminal strip. The timer is adjustable from 1 second to 17 minutes in 1 second intervals. A typical setting for most equipment is 14 minutes (840 seconds).