Honeywell T4M Programmable Modulating Thermostat Installation Guide
Programmable Modulating Thermostat
Quick Start Installation Guide
Compatible with OpenTherm appliances only.
Not compatible with 230V boilers, zone valve applications or 230V electric heating.
Installation in 3 steps…
To ensure your safety make sure the mains power is switched OFF before accessing wiring.
Wire the Thermostat
Find a suitable wall location away from draughts, direct sunlight or other heat sources, and where cables can be run from the boiler to the thermostat.
| A) Separate the wallplate from the thermostat, and using a screwdriver open the wallplate terminal cover to connect wires. | B) Connect wires according to wiring diagrams and clip the cover closed. |
OpenTherm Boiler
- When using multi-core cables: Only remove enough outer insulation to allow secure fixing of the cores into the terminal block.
- When using single-core cables: Secure them together with a cable tie as close as possible to the terminal block.
Power Up and Test
Power Up the Heating System and do a quick functional test on the thermostat to check that it switches the boiler.
Configure the System
Specific settings for the thermostat and heating system can be configured in the advanced menu.
Press and hold
| A) Press√ and |
B) Press+ and- buttons to change a parameter |
| C) Press√ the button to save the change (or press |
D) Press |
OpenTherm Data ID’s
An OpenTherm boiler can report alerts back to the Thermostat.
You can view these in the ‘OpenTherm® boiler alerts’ menu.
The OpenTherm Data IDs appear after the installer parameters (see the table above).
| N° | Description | Settings (default in bold) |
| Low load control | 0 = Off, 1 = On | |
| Control setpoint | 5 – 99°C | |
| Supply water temperature | 5 – 99°C | |
| Return water temperature | 5 – 99°C | |
| Max. supply water temperature | 5 – 99°C | |
| Hot water temperature | 5 – 99°C | |
| Hot water setpoint | 5 – 99°C | |
| Actual power | 0 – 99% | |
| Water pressure | 0.0 – 9.9 | |
| OTC control | 0 = Off, 1 = On | |
| OTC curve | 4 – 40 (16) | |
| Room compensation | 0 = Off, 1 = On |
Parameters
| N° | Description I- Settings (default in bold) | |
| Language | 1= EN | |
| Heating Cycle Rate (cps) | 3 (oil boiler / thermal actuator) 6 (gas or combi boiler / zone valve) 9 12 | |
| Minimum on time | 1- 5 (mins) (set to 4 mins for oil boiler) | |
| Lower Temperature Limit | 5 – 21 (°C) | |
| Upper-Temperature Limit | 21 – 35 (°C) | |
| Schedule options | 1= 7 days (different schedule each day of the week) 2 = 5 + 2 day (weekday + weekend schedule) 3 = 1 day (same schedule every day) | |
| Number of periods per day | 4 or 6 | |
| Fail Safe mode | 0 = Boiler off, 1 = Boiler 20% on / 80% off | |
| Backlight | 0 = Off, 1 = On (only on demand) | |
| Clock Format | 0 = 24 hr, 1 = AM/PM | |
| Daylight Saving time change | 0 = Off, 1 = Auto | |
| Temperature Display Offset | +/-3°C | |
| Restore Schedule Defaults | 0, 1 = reset | |
| Restore Factory Settings | 0, 1 = reset | |
| Optimisation | 0 = Disabled, 1= Enabled | |
Troubleshooting
| What’s happening? | What it could mean… | How to fix it… |
| The thermostat display is blank | Faulty wiring connection | Check heating system is powered |
| Faulty wiring connection | Check wiring at thermostat and boiler terminals | |
| Display = |
Faulty temperature sensor | Replace thermostat or check the wiring to remote temperature sensor if fitted |
| The thermostat shows heat demand but the boiler doesn’t respond | Boiler (water) already at temperature | Normal behavior – wait for water temperature to drop |
| Faulty wiring connection | Faulty wiring connection Check wiring at thermostat and boiler terminals |
EMC: 2014/30/EU and LVD: 2014/35/EU
The full text of the EU declaration of conformity is available at the following internet address: https://hwllhome.co/DoC
ErP: Class V (+3%), (EU) 811/2013
At the end of the product, life dispose of the packaging and product in a corresponding recycling center. Do not dispose of the unit with the usual domestic refuse. Do not burn the product.
Pittway Sarl, Z.A. La Pièce 4,
1180 Rolle, Switzerland
Country of origin: UK
© 2020 Resideo Technologies, Inc. All rights reserved.
The Honeywell Home trademark is used under license from Honeywell International Inc.
This product is manufactured by Resideo Technologies, Inc. and its affiliates.