Cart 0

How to choose the right electric sauna heater for your sauna

Choosing the right electric sauna heater can be confusing and it can be easy to make a mistake if you’re not sure what to look for.

Which power rating (kW) sauna heater do I need?

The first thing to bear in mind when deciding which sauna heater to go for is the size of your sauna. The internal volume of your sauna will dictate which power heater you will require, as well as whether you have space for a small wall mounted heater, or larger standalone heater. For each of our heaters the power requirement to sauna size guidelines are included within the product spec table. This is typically as follows (but varies model to model so please check the individual product):

Model Power Output

4.5 kW

6/6.8 kW

9 kW

10.5 kW

Capacity of the sauna


5–8/9 m³

8–14 m³

10–18 m³


We strongly suggest you consult a suitably qualified electrician or electrical engineer for the installation of these heaters. It is worthwhile having an initial consultation to discuss the power output of your home and whether you are able to draw the power needed for the heater, with the existing appliances in your home. Most U.K. domestic power supplies are between 240 and 220 volts, and 60 and 100 amps. This variation depends on a number of factors and is why unless you are suitably qualified yourself, you will need to consult a qualified electrician. Also, if you already have a large load on your domestic supply, a 9 or 10.5 kW heater may trip out the supply.

The cabling within your standard ring main is 16 amps, therefore a dedicated power supply is required from your distribution board, much like an oven or electric shower. A 6.8kW sauna heater will require an approx. 31 amp dedicated supply, a 9kW sauna heater would require an approx. 41 amp dedicated supplies and the 10.5kW sauna heaters approx. 48 amps. An electrician or electrical engineer will recommend the right solution for your individual requirements.

Do I need 3-phase or Single Phase?

Most homes in the UK will only have a single phase power supply and you would probably be aware if you have access to a 3-phase supply (though it is always worth asking a qualified professional). All heater models up to 9 kW are available in both 3 phase and single phase models which can be selected on the drop down menus of each product. 10.5 kW electric sauna heaters require a 3-phase power supply. The larger commercial sauna heaters such as the Narvi Ultra Big will require a specialist dedicated power supply.

Do I need the Narvi N2014E power card, control unit and thermostat for my electric sauna heater?

All our Narvi and Kota Electric sauna heaters have the option to use alternative control units and power supplies with the exception of the Narvi Steam Ready. We strongly recommend using the Narvi2014E power card, control unit and thermostat kit as it is the quickest, safest and easiest way to install the heaters on the U.K. 230v 1N system with all the necessary elements included. However, the heater is compatible with other standalone control units should you wish.

The Narvi NC Electric, Narvi Trio and Narvi Slim electric sauna heaters are now built with these control units integrated. Whilst these heaters can also be sold without should you wish to use a different controller and power card, having the integrated option from the point of manufacture makes the P.S.U and control unit cheaper to produce and therefore cheaper to you.

Should I use a wall mounted or standalone electric sauna heater?

The answer to this question is down to personal preference. Whilst space is a factor when choosing, wall mounted heaters better serving smaller saunas, the sauna flanges allow for standalone heaters to be fitted within sauna benching. Heaters such as the Narvi Slim can be used as both wall mounted or standalone, with the assistance of the Narvi Slim installation base. The real question that you should be asking is ‘How big a stone capacity should I have?’.

How big a stone capacity should I have for my sauna heater?

We at Finnmark believe sauna should be done in the traditional Finnish way. Following this doctrine, the Finns say that the more stone the sauna heater has, the softer and more pleasant the löyly (sauna steam/sauna atmosphere). From our experience this is very much true, therefore, the answer to this question is: The more the better!

Any other questions?

If you have any other questions, please do get in touch using the contact form below. You can also send us an email or call us on (01768) 489273. Don’t delay, get in touch today!