If you’ve noticed that your radiators keep emitting heat even when your Nest thermostat is set to "Off," you're likely experiencing a compatibility or wiring issue. Here's a breakdown of potential causes and solutions:
1. Nest thermostats are designed to "power steal" in systems without a common wire (C-wire). They draw small amounts of energy through connected wires, which can inadvertently trigger the heating system. Since your setup includes an oil-powered Burnham V8 boiler with wires connected to W1 and Rh, this could be the root cause.
Solution: Install a Nest Power Connector or an external 24V AC transformer to provide consistent power to the thermostat without disrupting the boiler. This isolates the thermostat from your heating system and prevents unintended heat activation.
2. Burnham V8 series boilers, especially older models, might have controls that are sensitive to wiring setups. If the thermostat wiring isn’t configured correctly, it could cause the boiler to stay active even when the thermostat is off.
Solution: Verify that the wiring matches the Nest’s installation guide for oil boilers. Common configurations for your system might require additional checks for jumper wires or relay settings.
3. If your system uses zone valves to control heating to different areas, a stuck or malfunctioning valve could allow hot water to circulate through the radiators regardless of the thermostat setting.
Solution: Inspect your zone valves and ensure they open and close properly. A service technician can confirm and repair any issues if needed.
4. Some boiler systems feature manual override switches or thermostatic radiator valves. If these are accidentally set to a heating mode, your system might operate independently of the thermostat.
Solution: Check all manual controls on the boiler and radiators to ensure they’re aligned with your thermostat settings.
Pro Tip for Nest Users
- Use the Nest Compatibility Checker on the Google Nest website to verify if your system is fully supported.
- In the Nest app, review your system settings to ensure the thermostat is configured correctly for an oil-powered boiler.
