resideo R8845U - User Manual

PRODUCT DATA
68-0215-02
R8845U Universal Switching Relay
APPLICATION
The R8845U Universal Switching Relay provides intermediate
switching of line- and low-voltage devices from a line- or
lowvoltage controller. The R8845U may be used to replace
several Resideo or competitive switching relays and is
typically applied in hydronic heating systems.
FEATURES
• Replaceable, socketed relays.
• Replacement relay common to other hydronic replacement
controls.
• Two troubleshooting LEDs.
• Push-to-test button.
• Replaceable transformer fuse.
• Low-voltage contact ratings for Powerpile® applications.
• Long-life DC relay drive control technology.
• Relays can be used with external 24 Vac or 24 Vdc supply,
line-voltage control, or with internal 24V transformer.
• One model replaces several competitor models.
• One model replaces many Resideo models: R182A,B,C,J;
R482A,B,C,J; R845A, R882A,B,C,J and RA832A. (See
Table 1, Replacement Cross Reference.)
SPECIFICATIONS
IMPORTANT
The specifications given in this publication do not
include normal manufacturing tolerances. There-
fore, this unit may not exactly match the listed spec-
ifications. Also, this product is tested and calibrated
under closely controlled conditions, and some minor
differences in performance can be expected if those
conditions are changed.
Model: R8845U Universal Switching Relay with 24V control-
ler for switching one- or two-line voltage loads and one
low-voltage load.
Electrical Ratings:
Voltage: 120 Vac, 60 Hz.
Thermostat Heat Anticipator Setting: 0.12A.
Transformer Ratings:
Primary: 120V, 60 Hz.
Secondary: 24 Vac, 12 VA maximum, 9 VA available for exter-
nal loads. Secondary protected by replaceable 1A auto-
motive fuse.
Contact Ratings: 7.4 AFL, 44.4 ALR on each set of line-volt-
age contacts; maximum connected load is 2000 VA.
Switching Action: Two Spst, plus Powerpile® rated low-volt-
age Spst. If normally closed contacts are needed, use
RA889A.
Temperature Ratings:
Ambient: -20°F to 120°F (-29°C to 49°C).
Humidity Ratings: 0 to 90% rh, non-condensing.
Electrical Connections: No. 8 captivated wire clamp screw
terminals.
Finish: Zinc plated steel.
Knockouts:
Case Bottom: Three 1/2 in. (13 mm) for conduit box.
Case Top: One 7/8 in. (22 mm) for wiring.
Approvals:
Underwriters Laboratories Inc. Listed: File no. E4436, Guide
no. XAPX.
Canadian Underwriters Laboratories Listed: Guide no.
XAPX7.

Summary

Specifications

Model

Identifies the R8845U Universal Switching Relay and its function.

Electrical Ratings

Details voltage, frequency, and thermostat heat anticipator settings.

Transformer Ratings

Specifies primary/secondary voltage, VA, and fuse protection.

Contact Ratings

Lists AFL, ALR ratings and maximum connected load.

Switching Action

Describes the relay configuration (Spst) and alternative for normally closed contacts.

Temperature Ratings

Defines the operating ambient temperature range.

Humidity Ratings

Specifies the acceptable non-condensing humidity range.

Electrical Connections

Notes the type and size of wire clamp screw terminals.

Finish

States the material and finish of the relay casing.

Knockouts

Details the size and location of conduit knockouts.

Approvals

Lists certifications from Underwriters Laboratories Inc. and Canada.

Installation

Mounting

Guidance on locating and securing the relay for new and replacement applications.

Wiring

Instructions for safe and compliant electrical connections, including warnings.

Control Options

24 V Thermostat Control

Wiring diagram for controlling the relay using a 24V thermostat.

Line Voltage Control

Wiring diagram for controlling the relay with a line voltage signal.

External Low Voltage Power Source

Wiring diagram for using an external 24V controller input supply.

Troubleshooting

Test Button

Explains the function of the test button for heat call simulation.

Heat Call LED

Describes LED behavior during heat calls and troubleshooting steps.

Relay LED

Explains when the Relay LED lights and indicates operational status.

Overview

1. Function Description
2. Important Technical Specifications
3. Usage Features
4. Maintenance Features
5. Installation Considerations

The Resideo R8845U Universal Switching Relay is a versatile device designed for intermediate switching of both line- and low-voltage devices, typically from a line- or low-voltage controller. It is primarily applied in hydronic heating systems and can replace several Resideo and competitive switching relays.

Function Description:

The R8845U integrates a transformer, two Single-Pole Single-Throw (SPST) line voltage relays, a SPST low-voltage relay, and various wiring terminals. When line voltage is supplied to the transformer, the relay is powered upon thermostat contact closure. The relay can also provide electrical isolation in low-voltage circuits if powered from an external 24 Vac or 24 Vdc source connected to the W(T) and C terminals. Fiber barriers are incorporated to separate line- and low-voltage connections, ensuring safety and proper operation.

Important Technical Specifications:

• Electrical Ratings:
  • Voltage: 120 Vac, 60 Hz.
  • Thermostat Heat Anticipator Setting: 0.12A.
• Transformer Ratings:
  • Primary: 120V, 60 Hz.
  • Secondary: 24 Vac, 12 VA maximum, with 9 VA available for external loads.
  • Secondary protected by a replaceable 1A automotive fuse.
• Contact Ratings:
  • Line-voltage contacts: 7.4 AFL (Amps Full Load), 44.4 ALR (Amps Locked Rotor) on each set.
  • Maximum connected load: 2000 VA.
• Switching Action: Two SPST, plus a Powerpile® rated low-voltage SPST. For normally closed contacts, the RA889A is recommended.
• Temperature Ratings:
  • Ambient: -20°F to 120°F (-29°C to 49°C).
• Humidity Ratings: 0 to 90% RH, non-condensing.
• Electrical Connections: No. 8 captivated wire clamp screw terminals.
• Finish: Zinc plated steel.
• Knockouts:
  • Case Bottom: Three 1/2 in. (13 mm) for conduit box.
  • Case Top: One 7/8 in. (22 mm) for wiring.
• Approvals:
  • Underwriters Laboratories Inc. Listed: File no. E4436, Guide no. XAPX.
  • Canadian Underwriters Laboratories Listed: Guide no. XAPX7.

Usage Features:

• Broad Compatibility: The R8845U is designed to replace numerous Resideo models (R182A,B,C,J; R482A,B,C,J; R845A, R882A,B,C,J; and RA832A) as well as several competitive models. This simplifies inventory and replacement processes.
• Thermostat Compatibility: It works with all Resideo electromechanical and most electronic 2- or 3-wire thermostats. Thermostats should have a 0.12A heating anticipator setting to match the R8845A Switching Relay's electrical rating.
• Flexible Power Options: Relays can be powered by an external 24 Vac or 24 Vdc supply, line-voltage control, or the internal 24V transformer.
• Low-Voltage Contact Ratings: Suitable for Powerpile® applications.
• Long-Life DC Relay Drive Control Technology: Enhances durability and reliability.
• Troubleshooting LEDs: Two LEDs are provided to assist with diagnostics:
  • Heat Call LED: Illuminates during a call for heat or when the test button is pressed, indicating proper thermostat or control operation.
  • Relay LED: Lights up when 120 Vac (L1) is present on the N.O. terminal (i.e., when COM/N.O. relay contacts are closed), confirming relay activation.
• Push-to-Test Button: Allows for manual testing of the heat call function, aiding in troubleshooting.

Maintenance Features:

• Replaceable, Socketed Relays: Simplifies replacement of individual relay components without needing to replace the entire unit. The replacement relay (part number 32002190-001) is common to other hydronic replacement controls.
• Replaceable Transformer Fuse: A 1A automotive fuse protects the secondary side of the transformer, and it can be easily replaced if blown.
• No Contact Cleaning Required: Relay contacts are designed for self-cleaning with a wiping action. Discoloration of contacts over time is normal and does not impede proper operation.
• Mounting Recommendations: For new installations, the relay should be mounted vertically on a solid wall or partition, close to the controlled device, ensuring accessibility for installation and service. To minimize transformer hum and relay noise, rubber or felt washers should be placed between the case and the mounting surface.

Installation Considerations:

• Installation should be performed by a trained, experienced service technician.
• All wiring must comply with applicable electrical codes, ordinances, and regulations.
• Only NEC Class 1 wire rated for at least 167°F (75°C) should be used for line voltage wiring.
• The switching relay terminals are approved for use only with copper wires.
• When controlling multiple line-voltage load devices in parallel, the total current must not exceed the relay load output ratings.
• The transformer core is not bonded; power supply must be disconnected before wiring to prevent electrical shock.
• The control case must be connected to earth ground using the provided grounding screw.

resideo R8845U Specifications

General

Brand	resideo
Model	R8845U
Category	Relays
Language	English