Honeywell Home DT135 Digital Wired Non-programmable Thermostat

Introduction

The Honeywell Home DT135 is a digital wired non-programmable thermostat designed for precise temperature control in various heating applications. Its user-friendly interface allows for easy temperature adjustments and mode selections. This manual provides essential information for the installation, operation, and maintenance of your DT135 thermostat.

Image: Front view of the Honeywell Home DT135 Digital Wired Thermostat, showing its LCD display and control buttons.

Key Features

• Digital Wired Non-programmable: Ideal for hydronic heating applications with standard and combi boilers, gas, oil, or electric heating systems (On/Off Relay 230V 5(2)A).
• High-Precision Control: Features digital TPI (Proportional Adaptive Mode) control to minimize temperature changes, ensuring comfort. The precise LCD shows room temperature in increments of 0.1°C.
• Preset Modes: Includes Comfort, Economy, and Holiday (frost protection) presets, allowing for quick temperature changes at the touch of a button.
• Compact Design: An ultra-compact design that complements any décor.
• Pump Protection: Activates the heating system pump for one minute every 24 hours to prevent seizure, extending the pump's lifespan.
• Low Battery Indicator: Provides a 60-day warning to replace batteries (requires 2 'AA' batteries, not included).

Image: Graphic illustrating key features such as easy installation, simple operation, and frost protection for the DT135 thermostat.

Setup and Installation

The DT135 thermostat is designed for wall mounting and wired connectivity. It is crucial to follow all local electrical codes and safety guidelines during installation. It is recommended that installation be performed by a qualified electrician.

Included Components:

• 1 x DT135 Thermostat
• Mounting accessories
• Instruction manual (this document)

Note: 2 'AA' batteries are required for operation and are not included in the package.

Wiring and Mounting:

The DT135 operates as a simple 'dry contact' switch. Ensure proper wiring connections to your heating system. The unit is designed to be compact, so careful management of wiring within the wall void may be necessary. Secure the thermostat to the wall using the provided mounting accessories.

DIP Switch Configuration:

Inside the thermostat, there are DIP switches that may need to be configured for optimal performance with your specific heating system. Refer to the detailed wiring diagram and DIP switch settings provided in the separate installation guide (if applicable) or on the product packaging. Incorrect settings can affect the thermostat's ability to call for heat or its operational cycles. For example, adjusting DIP switch 3 might be necessary if the boiler is not responding correctly.

Operating Instructions

The DT135 thermostat features an intuitive interface with an LCD display and four control buttons.

Display Overview:

The LCD continuously displays the current room temperature in 0.1°C increments. When adjusting the temperature or selecting a mode, the display will show the target setting.

Control Buttons:

• 🌙 (Moon Icon) Button: Activates the 'Economy' or 'Night' preset temperature.
• ☀️ (Sun Icon) Button: Activates the 'Comfort' or 'Day' preset temperature.
• ▼ (Down Arrow) Button: Decreases the target temperature.
• ▲ (Up Arrow) Button: Increases the target temperature.

Setting Temperature:

1. Press the ▲ or ▼ buttons to adjust the desired temperature. The display will show the new target temperature.
2. The thermostat will automatically maintain the set temperature.

Using Preset Modes:

The DT135 offers three convenient preset modes:

• Comfort Mode: Typically used for daytime or active periods. Press the ☀️ (Sun Icon) button to activate.
• Economy Mode: Suitable for nighttime or periods of reduced activity. Press the 🌙 (Moon Icon) button to activate.
• Holiday (Frost Protection) Mode: Designed to maintain a minimum temperature to prevent pipes from freezing when the property is unoccupied for an extended period. This mode is typically activated by holding down a specific button combination or through a dedicated setting (refer to the full installation guide for specific activation).

Heating Control Modes:

The DT135 offers flexibility with two heating control modes, configurable via internal settings (often DIP switches):

• Proportional Adaptive Mode (TPI): This mode learns the thermal characteristics of your home and optimizes heating cycles (e.g., 15 or 20-minute cycles) to maintain a very stable temperature with minimal fluctuations.
• Conventional Mode: Operates with a fixed temperature span (hysteresis) of 0.5°C. The heating will turn on when the temperature drops 0.5°C below the set point and turn off when it reaches the set point.

Maintenance

Battery Replacement:

The DT135 thermostat is powered by 2 'AA' batteries. A low battery indicator will appear on the display approximately 60 days before the batteries need to be replaced. To replace the batteries:

1. Carefully remove the front cover of the thermostat.
2. Replace the old 'AA' batteries with new ones, ensuring correct polarity.
3. Reattach the front cover securely.

Important: There is a finger guard over the live wires when replacing batteries, enhancing safety.

Pump Protection Feature:

To prevent the heating system's pump from seizing due to inactivity, the DT135 automatically activates the pump for one minute every 24 hours. This feature helps maintain the longevity and reliability of your heating system's pump.

Troubleshooting

If you encounter issues with your DT135 thermostat, consider the following common solutions:

Thermostat Not Calling for Heat / Boiler Not Running:

• Check Batteries: Ensure the batteries are not depleted and are installed correctly.
• Verify Temperature Setting: Make sure the set temperature is higher than the current room temperature.
• Inspect Wiring: Confirm that all wiring connections are secure and correct according to the installation guide.
• DIP Switch Configuration: Incorrect DIP switch settings can prevent the thermostat from communicating properly with the boiler. Review the DIP switch settings, particularly switch 3, and adjust if necessary.

Thermostat Clicking On and Off Frequently:

• Heating Control Mode: If the thermostat is in 'Proportional Adaptive Mode (TPI)' and seems to be cycling too frequently, consider switching to 'Conventional Mode' with a 0.5°C temperature span. This can be adjusted via the internal DIP switches.
• External Factors: Drafts, direct sunlight, or proximity to heat sources can affect temperature readings and cause frequent cycling. Ensure the thermostat is located in an appropriate area.

Display Issues:

• Blank Display: Replace batteries.
• Incorrect Temperature Reading: Ensure the thermostat is not exposed to extreme temperatures or direct drafts.

If problems persist after attempting these solutions, contact Honeywell Home customer support or a qualified HVAC technician.

Specifications

Image: Graphic illustrating the dimensions of the Honeywell Home DT135 thermostat: 79mm width, 79mm height, and 22mm depth.

Warranty and Support

For warranty information and technical support, please refer to the documentation included with your product or visit the official Honeywell Home website. Keep your purchase receipt as proof of purchase for any warranty claims.