By the SaunaKitsUK.co.uk — The UK's Home Sauna Buying Guide Team · Updated May 2026 · Independent, reader-supported

Sauna Heater Guide UK: Electric, Wood-Burning or Infrared — What You Need

A sauna heater is the heart of your home installation. Get it wrong—too small, wrong fuel type, poor controls—and you'll end up with a space that never quite hits temperature, costs a fortune to run, or feels like a different room entirely from what you imagined. The good news is that choosing the right heater is straightforward once you understand what each type actually does and what your space demands.

Electric Heaters: Reliable and Practical

Electric heaters are the most common choice for UK home saunas, especially those under 12 kW. They heat fast, switch on demand, and require no fuel storage or flue management. A typical 6 kW model will warm a small sauna (under 6 cubic metres) to 80°C in 30–45 minutes. Larger homes or commercial installations often jump to 8–12 kW to reduce warm-up times.

The controls are straightforward: a thermostat lets you set your target temperature, and the heater cycles on and off to maintain it. Some units offer variable power settings, which is genuinely useful if you want faster pre-heating or more gentle sessions. Built-in safeties like overheat switches are standard.

On the downside, electric heaters require dedicated circuits and proper wiring. A 6 kW unit needs a 32 amp supply; anything above 9 kW typically demands a three-phase connection, which isn't present in all UK homes. Installation costs reflect this—you'll often need an electrician, and upgrading your consumer unit may be necessary. Running costs are proportional to your electricity rate, so in winter they're not cheap. There's also no romance to it—the heater sits in a corner, often hidden by a guard, and produces heat without ceremony.

Wood-Burning Heaters: Traditional and Atmospheric

Wood-burning models are the other classic option. They create a quite different experience: the ritual of loading wood, the smell, the visible flame, and genuine warmth that feels old-fashioned in a good way. For those with an outdoor sauna or a garage build, they're excellent.

The core appeal is self-sufficiency and atmosphere. Once lit, they'll hold temperature reliably as long as you keep feeding them. No electricity needed—genuinely off-grid. They're also very durable: a cast-iron wood heater will outlast most buildings if maintained properly.

The realities are less romantic. You need a proper flue and somewhere for smoke to exit, which adds complexity and cost to installation. Firing them up takes 1–2 hours before the sauna is usable, so they're not for quick sessions. They demand real attention: you can't set them to a temperature and walk away. They're also much more regulated now—many UK councils require chimney sweeping permits and compliance checks, especially if you're building to fire regulations. Wood storage space, keeping fuel dry, and the mess are genuine considerations. And frankly, many people find tending a fire weekly isn't actually relaxing; it's a chore.

Infrared Heaters: Lower Temperature, Different Feel

Infrared heaters have gained popularity as a "gentler" alternative. They work at lower air temperatures—typically 45–60°C—and radiate heat directly into the body rather than warming the air. This is legitimate physics, but it creates a fundamentally different experience from a traditional sauna.

For people with certain health conditions or who find conventional saunas too intense, infrared cabins can be worthwhile. They cost less to run (lower wattage, lower air temperature) and warm up faster. Installation is simple—most are plug-and-play, no wiring needed.

However, they're not saunas in the traditional sense. If you're expecting steam, high humidity, or that deeply heated-air experience, you'll be disappointed. Many people who've used a proper Finnish sauna find infrared underwhelming. Resale value tends to be lower because the category feels less established. They also often require more maintenance, with elements and insulation degrading over time. They're a reasonable choice for wellness-focused spaces, but don't assume they're simply "better"—they're different.

Sizing: kW and Volume

The rule of thumb is roughly 1 kW per cubic metre of sauna space, though this varies by insulation quality and climate. A 2×2×2 metre interior (8 cubic metres) typically needs 8 kW. If your sauna is well-insulated and in a mild location, you might get away with 6 kW; if it's poorly insulated or you're in northern Scotland, 10 kW makes sense.

Check the manufacturer's guidance for your specific model. Undersizing means frustratingly slow warm-up and temperature plateaus; oversizing wastes energy and creates uneven heating.

Stone Capacity and Control Quality

Stone capacity matters more than most people realise. Heaters with larger stone baskets (10–15 kg for domestic electric units) create better humidity and more stable temperatures. Small baskets cool down faster and make the air feel dry.

Control types vary. Simple on/off switches are cheap but crude. Thermostats are standard and reliable. Digital controls with preset programmes are convenient if you use your sauna regularly. Some heaters now include remote controls, which is a genuine quality-of-life improvement.

What to Look For

Choose the heater type that matches your space and habits: electric for convenience and reliability, wood-burning for atmosphere and off-grid appeal (if you've got time for it), infrared for lower-temperature wellness use. Match the kW to your volume, ensure the stone capacity is adequate, and prioritise good temperature controls. Installation matters as much as the heater itself—poor wiring or inadequate ventilation will undermine any unit, regardless of quality.