Taco i Series

The iSeries-R is a microprocessor-based valve designed to regulate the supply water temperature to a heating system by modulating
the position of an iSeries Mixing Valve. The iSeries-R operates the valve to provide outdoor reset to the heating system. A boiler sensor
installed on the return line to the boiler is used to protect the boiler against flue gas condensation.
Outdoor Reset
In order to properly control a hot water heating system, the heat supplied to the build-
ing must equal the heat lost by the building.
• The heat supplied to the building is directly proportional to the temperature of the
water and the surface area of the heating element. The higher the temperature of the
water flowing through the heating terminal, the higher the heat output.
• The heat lost from a building is dependent on the outdoor temperature. As the out-
door temperature drops, the building heat loss increases.
These two facts lead to the concept of outdoor reset which increases the supply
water temperature as the outdoor temperature drops. Using this approach, the heat
lost from the building is matched by the heat provided by the terminal units, therefore
providing more comfort and energy savings.
Reset Ratio
The Reset Ratio sets the relationship between outdoor temperature and supply
water temperature. It determines the amount the supply water temperature is raised
for every 1 degree outdoor temperature drop. For example, if a Reset Ratio of 1.2
is selected, the supply water temperature is increased by 1.2 degrees of every 1
degree of outdoor temperature drop.
2-Way / 3-Way Mixing
An iSeries Mixing Valve may be used to mix the hot boiler water temperature with the cooler return water temperature from the system
loop. The position of the iSeries Mixing Valve is modulated in order to inject different rates of hot water into the cool system return water.
This allows for virtually any water temperature to be supplied to the heating system. When deciding between a 2-way or 3-way valve,
maximum flow rates must be considered. See the charts on page 2 before selecting style of valve / piping.
Most boilers cannot operate at low temperatures, therefore the iSeries-R can be modulated back in order to prevent the boiler from
operating at cold temperatures, by installing the boiler return sensor.
102-145
Instruction Sheet
i Series - Outdoor Reset (iSeries-R)
2-Way and 3-Way i Series Mixing Valves
SUPERSEDES: New EFFECTIVE: August 1, 2003
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Taco i Series Specifications

General

Category	Control Unit
Manufacturer	Taco
Series	i Series
Input Voltage	24 VAC
Housing Material	Plastic
Dimensions	4.5 x 3.5 x 1.5 inches (114 x 89 x 38 mm)
Weight	0.5 lbs

Summary

Outdoor Reset

Reset Ratio Concept

Explains the relationship between outdoor temperature and supply water temperature.

2-Way and 3-Way Mixing

Mixing Valve Selection

2-Way iSeries Mixing Valve Selection

Procedure for sizing the 2-way iSeries mixing valve based on design load.

3-Way iSeries Mixing Valve Selection

Procedure for selecting the 3-way iSeries mixing valve based on pressure drop.

Sequence of Operation

Power Up and Heat Request

Explains how the iSeries-R starts operation upon receiving power.

Reset Ratio and DIP Switch Settings

Maximum Minimum System Supply Temperature

Sets maximum and minimum supply water temperatures for system protection via DIP switches.

Minimum Boiler Return Temperature

Protects boiler from low return temps, adjustable via DIP switch 3.

Warm Weather Shut Down

Shuts down unit when outdoor temperature exceeds 70°F, controlled by DIP switch 4.

Valve Installation

Actuator Installation Removal

Details how to attach and detach the actuator from the valve body.

Wiring and Sensor Installation

Powering the Control

Explains how to connect the power supply for intermittent or continuous operation.

Sensor Connections

Instructions for connecting outdoor, system supply, and boiler return sensors.

Troubleshooting

Multi-Status LED Indicators

Explains the meaning of different LED status indicators and error codes.

Testing the Sensors

Guide to testing sensor resistance and accuracy using a meter.

Product Specifications

Flow Coefficients and Pressure

Provides Cv values and pressure ratings for valve sizing and selection.

Materials of Construction

Lists the materials used for the actuator and valve components.

Dimensions and Weights

Provides physical dimensions and weights for different valve sizes.

Ordering Information

Replacement Parts

Lists part numbers for replacement sensors and actuators.

Limited Warranty Statement