Wattage & Amperage Limits — Mysa for In-Floor Heating

Last updated: September 2, 2026

Your floor heating system's wattage must stay within Mysa's limits. If it is over, Mysa cannot safely control it.

Maximum load by voltage

  • 120V — up to 1,900W

  • 208V single-phase — up to 3,328W (16A)

  • 240V — up to 3,800W (15A)

The thermostat is rated 120–240V~, 60Hz, 16A.

If your system is over the limit

  • Have a qualified electrician split or redesign the heating zones so each thermostat stays within the supported voltage and load

  • Use one Mysa thermostat per compatible zone

  • A relay or contactor design is only acceptable if a qualified professional designs and installs it

Do not wire a system above these limits directly to Mysa. See How to Find Your Floor Heating System's Wattage to locate your rating.