Honeywell BDR91 - User Manual

Other manuals for Honeywell BDR91

Installation12 pages

Questions and Answers

B
brandonrobbinsJul 25, 2025
Why is the red LED on my Honeywell Thermostat relay box illuminated?
- M
  Melanie KnoxJul 25, 2025
  The red LED on the relay box illuminates because it's not receiving radio frequency (RF) signals from the room thermostat. This could be due to the thermostat being in a location where the RF signal is blocked, or because the thermostat batteries are dead. Try relocating the room thermostat as per the installation instructions or replace the batteries in the room thermostat.
C
christopher81Aug 1, 2025
What to do if my Honeywell Thermostat relay box doesn't react to setpoint changes?
- D
  davisjustinAug 1, 2025
  If the relay box isn't responding to setpoint changes from the room thermostat, it's likely that the thermostat and relay box aren't properly connected. You should reset the relay box by holding the push button for 15 seconds. Then, follow the binding procedure as described in section 5) Additional Installation Information.
T
tcohenAug 10, 2025
What to do if the red LED is on and the green one is flashing after binding Honeywell Thermostat?
- M
  michellekaiserAug 10, 2025
  If, after binding, the red LED is on and the green one flashes every 3 seconds on the relay box, it indicates an incorrect or incomplete binding procedure, or the thermostat was incorrectly positioned during binding. Repeat the binding procedure, ensuring the room thermostat is approximately 1 meter away from the relay box.
B
Billy MaxwellAug 16, 2025
How to make the Honeywell Thermostat relay switch on if it only displays the symbol?
- T
  Tammy MartinezAug 16, 2025
  When the room thermostat displays the symbol, it's normal for the relay not to immediately switch on. To activate it, adjust the temperature setpoint by a few degrees using the button. The relay box should then switch on after a short delay.

Summary

Installing the CM700 Wireless System

Installing the Relay box

Instructions for installing the RF relay box, including placement and wiring.

Installing the Room Thermostat

Steps for installing the wireless room thermostat, including battery insertion and setup.

System Check

Procedure to verify the correct installation and operation of the thermostat and relay box.

Basic Operation of the System

Automatic Operation

How the system operates automatically based on thermostat signals.

Temporary Manual Override

How to manually override the relay box position temporarily.

Communications Loss

What happens and how the system behaves when RF communication is lost.

Installer Mode

Entering the Installer Mode

Instructions on how to access and navigate the installer settings menu.

BDR91 Relay box Fail-Safe Mode Setup

Configuring the relay box behavior during RF communication loss.

Using the Room Thermostat for Specific Applications

Guidance on configuring the thermostat for different heating system types.

Using the Special Features of the Room Thermostat

Explanation and configuration of special thermostat features like optimisation.

Installer Parameters Table

Category 1 - Room Thermostat Settings

Details of configurable parameters for room thermostat settings.

Category 2 - System Settings

Details of configurable parameters for system-wide settings.

Additional Installation Information

Binding; Rebinding Procedure

Steps to establish or re-establish communication between thermostat and relay box.

Multi-Zone System

Information regarding the setup and configuration of multi-zone systems.

Trouble Shooting

Trouble Shooting Guide

Common problems, their causes, and remedies for the system.

Diagnostic Mode

How to access diagnostic information for system checks and troubleshooting.

The Honeywell CM700 Wireless (CM727 or CM721) is a modern, programmable room thermostat designed for controlling a single heating system component, such as a boiler, pump, or zone valve. It communicates wirelessly with a BDR91 relay box using an 868MHz Radio Frequency (RF) band. The system is pre-configured at the factory, ensuring a fast and easy installation process when products from a system pack are installed at the same site. If units are separated or mixed, a binding/rebinding procedure is available to establish communication.

Function Description:

The CM700 Wireless system operates by the room thermostat sending heat demand signals (0-100%) to the BDR91 relay box. The thermostat displays a flame symbol on its LCD when heat is required. The relay box then switches the heating device on or off to meet the system's current requirements. The green LED on the relay box indicates its status: on for relay activation, off for relay deactivation.

The thermostat features a large LCD display with backlighting for improved visibility during daily use. It follows Honeywell's established programming philosophy, allowing users to set up heating schedules.

Usage Features:

Automatic Operation: Once programmed, the system operates automatically according to the set heating schedule.
Temporary Manual Override: The relay box includes a push button that allows for a temporary manual override of the current relay position. However, the system will revert to automatic operation upon receiving the next signal from the room thermostat, as automatic control has higher priority.
Installer Mode: This mode allows for customization of system settings for specific applications, modification of special features, and alteration of factory preset parameters. Parameters are categorized into "Room Thermostat Setup" and "System Setup."
- Room Thermostat Settings (Category 1): These parameters include display format (AM-PM/24hr), options to reset time/temperature programs to factory defaults, auto Summer/Winter time change enable/disable, LCD backlighting control, upper and lower temperature limits, optimization enable/disable (variable start time), temperature offset adjustment, proportional band width, scheduled maintenance alert period (in months), and a full reset to factory defaults.
- System Settings (Category 2): These parameters include minimum boiler ON time, cycle rate (cycles per hour), pump exercise enable/disable, system synchronization (allowing the room unit to be configured as a synchronizer), and loss of communications instruction (defining the relay box's behavior if RF communication is lost).
Special Features (Configurable via Installer Mode):
- Optimisation (Variable Start Time): The thermostat can adjust the heating start time in the morning/afternoon to ensure the desired temperature is reached by the program period's start, with a maximum adjustment of 2 hours.
- Scheduled Maintenance Alert Period: Users can set a period (1-48 months) after which the CM721/CM727 will display a 'SERVICE' icon, reminding them that maintenance is due. Setting the value to zero disables this function.
- Summer/Winter Auto Time Change: This feature automatically adjusts the time on the last Sunday of March and October. It is factory enabled.
- Temperature Offset: If the thermostat is in a particularly hot/cold location, or if the homeowner wants the displayed temperature to match another appliance, the measured/displayed temperature can be adjusted by +/- 3°C.
- Upper/Lower Temperature Limit: The normal upper temperature limit of 35°C can be reduced to 21°C for energy saving, and the normal lower limit of 5°C can be increased up to 21°C to protect inhabitants from cold.
RF Communication Check (Test Mode): This mode allows installers to verify reliable RF communication between the thermostat and relay box. The thermostat sends test signals, and the relay box flashes its green LED every 6 seconds if communication is successful.
Locating the Room Thermostat: Guidance is provided on finding a suitable location for the thermostat to ensure reliable signal transmission, considering factors like distance from metal objects and other electrical equipment.

Maintenance Features:

Battery Replacement: The room thermostat is powered by 2 x AA LR6 Alkaline Batteries. Instructions are provided for easy battery replacement.
BDR91 Relay Box Fail-Safe Mode Setup: This feature defines the relay box's output relay status if RF communication is lost (e.g., due to discharged batteries in the thermostat). The factory setting keeps the relay permanently off, but it can be changed to cycle the relay output at 20% on and 80% off, which can enable frost protection.
Troubleshooting Guide: A comprehensive guide is included to help diagnose and resolve common issues, such as the relay box not switching on, lack of response to setpoint changes, or communication loss. It provides possible causes and recommended remedies.
Diagnostics Mode: The CM727/721 room thermostat has a user-accessible diagnostics mode that provides useful information for remote service personnel and allows checking boiler operation. It displays information like model ID, date code, and checksum.
Binding/Rebinding Procedure: This procedure is necessary if any system components are replaced or if the relay box has incorrect or no binding data. It involves resetting the relay box, entering binding mode, and sending a binding signal from the thermostat to establish communication.