Taco Variable Speed Pump Injection Mixing Control, EXP

The PC705-2 is a microprocessor-based PID control designed to regulate the supply water temperature to a heating system by controlling a boiler and the speed of an injection pump. The PC705-2 controls the system supply water temperature based on the outdoor air temperature (outdoor reset). A boiler sensor can be connected in order to prevent corrosion in the boiler due to flue gas condensation. If the PC705-2 is controlling the boiler supply water temperature, the control continuously adjusts the boiler differential in order to optimize the firing cycles of the boiler, prevent large water temperature swings, and increase the efficiency of the system. A wiring harness is provided to be easily connected to the Taco Expandable (-EXP) Controls.

The PC705-2 also includes features such as an automatic reset ratio calculation, Warm Weather Shut Down (WWSD), and a maximum supply water temperature setting.

A wiring harness is provided to be easily connected to the Taco Expandable (-EXP) Controls.

Technical Information

Taco Add on Controls Brochure

Taco PC705-2 Installation Instructions

Taco Add On Submittal

Specifications

Control: Microprocessor PID Control; This is not a safety ( limit ) control
Dimensions: 43/4” H x 2 7/8” W x 1 7/8” D
Approvals: CSA CVS; Meets ICES & FCC regulations for EMI/RFI
Ambient Cond.: Indoor use only
Power Supply: 24 VAC 3VA (Powered by -EXP Control)
Variable Pump: 120 V (ac) 1.8 A 1/2 hp, fuse 2.5 A 250 V
Relays: 24 V (ac) 5 A, pilot duty 240 VA
Sensors: 1 outdoor air and 2 supply water
Mix Start: 35 to 150°F ( 2 to 66°C )
Outdoor Start: 35 to 85°F ( 2 to 29°C )
Mix Design: 70 to 220°F ( 21 to 104°C )
Outdoor Design: -60 to 32°F ( -51 to 0°C )
Boiler Minimum: Off, 80 to 180°F ( 27 to 82°C )
WWSD: Off, 35 to 100°F ( 2 to 38°C )
Units: °F, °C