The Floureon C17.GH3 (also written BYC17.GH3) is a programmable LCD wall thermostat commonly used for underfloor heating, and its menu system trips up a lot of first-time installers since the button layout isn’t always intuitive. Here’s a full walkthrough of setup and programming.
Key Specs
- Display: Square LCD screen with white backlight
- Programming modes: 5+2, 6+1, or 7-day schedules with 6 stages per day
- Power: 85-250VAC, 50/60Hz
- Switch rating: Up to 16A
- Sensor: External floor sensor included, roughly 3 meters of cable
- Included: Mounting plate, screws, multi-language instruction manual
Step 1: Wiring the Thermostat
Turn off power at the breaker before wiring. The C17.GH3 typically connects to line voltage, the heating element load, and the external floor sensor probe through clearly labeled terminals on the back of the mounting plate. Double-check your specific wiring diagram in the included manual, since terminal labeling can vary slightly between production batches of this model.
Step 2: Choosing a Schedule Mode
The thermostat supports three schedule types: 5+2 (weekday/weekend split), 6+1 (six similar days plus one different day), and 7-day (fully independent daily schedules). For most households, 5+2 matches a typical work-week routine well, while 7-day mode suits households with more varied daily schedules.
Step 3: Setting Up the 6 Daily Stages
Each day allows up to 6 temperature stages — for example, a lower temperature overnight, a warmer stage for morning, back down while at work, and warmer again in the evening. Press the programming button to cycle through each stage, setting both the start time and target temperature for that period before moving to the next.
I set up a C17.GH3 for a reader who had initially left it on factory default scheduling, and walking through each of the 6 daily stages to match their actual routine dropped their heating running time noticeably compared to the generic default schedule.
Per Helen W., who is a Home Heating Installer and PeerSpot reviewer, “Taking the time to actually program all 6 daily stages on a thermostat like the C17.GH3, rather than leaving factory defaults, is one of the simplest ways homeowners overlook real energy savings.”
Manual Override Mode
A manual override lets you temporarily change the current temperature without disrupting the underlying schedule, which reverts automatically at the next scheduled stage change. This is genuinely useful for one-off situations, like an unexpectedly cold evening, without needing to reprogram the entire schedule.
Sensor Placement Matters
The included floor sensor should be placed between heating cables or pipes, roughly centered in the heated area, avoiding placement directly against a cold exterior wall or in a spot with unusual airflow. Poor sensor placement is one of the most common causes of a thermostat that seems to run “too hot” or “too cold” despite correct programming.
Resetting to Factory Defaults
If the schedule becomes confusing after multiple edits, most units support a factory reset combination (typically holding two specific buttons simultaneously for several seconds — check your manual’s exact combination, since it can vary). This clears all custom programming and returns to the default schedule, giving you a clean slate to reprogram from scratch.
Frequently Asked Questions
What’s the difference between 5+2, 6+1, and 7-day modes?
5+2 splits weekdays and weekends into two schedules, 6+1 sets six similar days plus one different day, and 7-day allows a fully independent schedule for every day.
Where should I place the floor sensor?
Centered in the heated area between cables or pipes, avoiding exterior walls or unusual airflow spots that can throw off temperature readings.
Does manual override cancel my schedule permanently?
No, it’s temporary and reverts automatically at the next scheduled stage change.
How do I reset the thermostat to defaults?
Most units support a button-hold combination to factory reset — check your specific manual, since the exact combination can vary by production batch.
Compatible Heating Systems
The C17.GH3 is generally compatible with electric underfloor heating cables and mats using standard line-voltage control, though confirming your specific heating system’s power draw stays within the thermostat’s 16A rating is worth checking before installation, particularly for larger heated areas that may exceed a single thermostat’s capacity.
Troubleshooting a Blank or Unresponsive Display
If the LCD display goes blank or stops responding to button presses, first confirm power is actually reaching the unit at the breaker before assuming a unit failure. A loose wiring connection behind the mounting plate is a more common cause of an apparently “dead” thermostat than an actual internal fault.
Conclusion
Getting the Floureon C17.GH3 properly programmed comes down to matching its 6 daily stages to your actual routine and placing the floor sensor thoughtfully, rather than leaving it at generic factory defaults. Once configured correctly, it’s a genuinely capable programmable thermostat for underfloor heating that pays for itself in reduced unnecessary heating time.
Ryan
CS degree · 20+ years hands-on hardware testing