A 18 kW electric sauna heater from HUUM, rated by the maker for 18–28 m³ (about 636–989 ft³, our conversion). Every figure below is HUUM's own, linked to where it is published.
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Amazon — WiFi UKU Control (Glass)
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As published by HUUM, read on 2026-09-23. Makers revise their products; check HUUM's current specification before you buy. Figures marked "about" are Saunakivi's unit conversions of the maker's figure.
Finnleo states: 5 years parts (traditional sauna heater), residential; 2 years in-field labor + 3 years at-factory labor (non-commercial); commercial: 2-year parts-only. HUUM states for the HIVE 18: 3 years (private use); 1 year (commercial use).
Harvia · electric · 8 kW · rated for 251–424 ft³ (about 7.1–12 m³, our conversion)
Harvia · electric · 4.5 kW · rated for 100–211 ft³ (about 2.8–6 m³, our conversion)
Harvia · electric · 6 kW · rated for 170–300 ft³ (about 4.8–8.5 m³, our conversion)
Harvia · electric · 9 kW
HUUM · electric · 6 kW · rated for 5–9 m³ (about 177–318 ft³, our conversion)
HUUM · electric · 9 kW · rated for 8–13 m³ (about 283–459 ft³, our conversion)
HUUM lists 18 kW. Related question: What size sauna heater do I need?
HUUM rates it for 18–28 m³ (about 636–989 ft³, our conversion). See our heater sizing guide for how makers adjust that figure for glass and uninsulated walls.
HUUM lists 240 V 2~ or 208 V 2~. Related question: Does a sauna heater need 240 V, or will 120 V work?
HUUM lists 50+50 A (240 V), 40+40 A (208 V). The installation manual and a licensed electrician have the final word. Related question: What breaker does a sauna heater need?
HUUM lists: The UKU control system set already includes a black plastic control panel CLASSIC Black.
HUUM lists: 3 years (private use); 1 year (commercial use).
Source: HUUM Limited Warranty Terms and Conditions (v4, ENG)
More from HUUM: all HUUM products on Saunakivi.