If you're posting a request for installation help, please provide as much info about your system as possible. For example, for help regarding connecting a smart thermostat, please include details about your system including whether you have gas/electric, heat pump, number of heat stages, A/C condenser, etc.

Retrofit Danfoss

My existing thermostat is the Danfoss FP715si thermostat and is 230VAC or 24VAC electronic manual (http://heating.danfoss.co.uk/PCMPDF/38161v01s7-06.pdf)

I want to retrofit this with the Ecobee 3 SMART wifi thermostat. After emailing Ecobee 3 tech support they stated that 'our thermostat run off a 24V system. This [Danfoss] thermostat looks to be running on 230V. This thermostat is also a communication type thermostat. It does not have the standard wire terminals that our thermostat requires'

The Ecobee 3 thermostat comes with a power extender kit for existing installations that do not have a C (common) wire. Do tech support mean this wire when they say 'standard wire terminals'? The wiring diagram on page 5 of the manual is not clear at all


  • The installation manual you've linked to appears to be for a UK-based system. AIUI, systems in North America follows a different set of conventions and standards than those in the UK. The Ecobee3 is designed for NA systems and cannot safely be made to work elsewhere.


  • The Danfoss is 230VAC, the Ecobee is 24VAC, so a transformer should fix that. I would also need a different wire for the missing communications wire. How would I get this?

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