One of the most important parts of designing and building a Sauna is determining the correct size Sauna heater (either electric or wood fired) for your space. While we have a guide for determining what size your sauna should be, in this guide we’re going to talk about how to pick the correct sized heater for your Sauna.
We receive plenty of phone calls where folks ask about buying a smaller sauna heater simply because it’s cheaper. If you’ve gone through the cost of building a Sauna, the very last thing you want to short change yourself on is the heater.
Buy one that’s recommended for the size of your room and you’ll have no reason to consider upgrading later. Should you decide to save the money and buy an underpowered heater, don’t hesitate to call us at (763)688-1488 when you realize you want more heat down the road! We’d be happy to help you pick the correct sized heater, whether it’s electric or wood fired. Still in the buying process? Take a look at our Sauna Heaters for Sale and contact us with any questions!
Why Sauna Heater Size Matters In Sauna Rooms
It’s important that you have the correct size heater in your sauna room. Selecting the correct heater will ensure reaching your selected temperature in a reasonable time (20-30 minutes is typical). If your heater is undersized, it will take longer to heat the space and require more work from the heater. If the heater is oversized, the elements will cycle on less often, which affects the temperature of the rocks in the heater. If you like to throw steam (of course you do) you want to keep the rocks hot to give a good steam.
Factors to consider when Selecting the correct size (Kilowatt) heater
- Size of the room (cubic feet). The bigger the room, the longer it will take the heater to get the room to temperature. We will discuss height specifically below.
- Height of the room. Height of the sauna room is very important. You should never have higher than a 8 foot ceiling in a sauna. The ideal height is 7 feet. The reason for this is because heat rises. One foot of height in the sauna is about a 15 degree F difference. When you have a higher ceiling, the heater has to work more to get up to temperature. All Finnleo branded electrical heaters are UL safety listed. The max temperature at ceiling with a UL listing is 194 degrees F. At head level when sitting on the upper bench, the temperature in a 7 foot tall ceiling is about 160 F. With a 8 foot tall ceiling, the temperature at head level is about 140 F.
- Proper ventilation and insulation. If your sauna is not properly insulated and have proper ventilation, the heater will be comprised. The sauna room should be insulated with R11 or better Fiberglass Batt insulation in the wall and ceiling. Preferably double layered in the ceiling, or using a higher rating in the ceiling as that’s where most of the heat goes. You should also use a foil vapor barrier over the studs & insulation to help reflect and hold the heat in the room. Ventilation is very important as well. Finnleo heaters have a 3-1/2″ x 4-1/2″ in-take vent directly behind the heater about 2-3″ off the floor, and a 4″x6″ outlet vent on the wall opposite the heater about 26″-32″ off the floor. Both vents are passive, you don’t want to use mechanical venting in a sauna. The in-vent draws heater under the heater and through the top and then cycles through the room and out the out-vent. This circulation minimizes “hot zones” in the room. If the room is not vented, there is a hot zone directly above the heater. This is a problem because this is where the thermometer is placed in the room. So the thermometer will read a higher temperature here and cycle the heater off when the opposite side of the room may read a temperature as different as 20-30 F lower.
Below are the recommended cubic footage and corresponding heater. Assuming 7′ height, and proper ventilation & insulation.
- KW | < Square ft | Cubic Feet
- 2.1 KW | < 14 ft^2 | 70-100 ft^3
- 3.0 KW | < 21ft^2 | 100-150 ft^3
- 4.5 KW | < 30 ft^2 | 100-210 ft^3
- 6.0 KW | < 45 ft^2 | 175-310 ft^3
- 8.0 KW | < 60 ft^2 | 250-425 ft^3
- 10.5 KW | < 85 ft^2 | 390-600 ft^3
- 12.0 KW | < 105 ft^2 | 510-740 ft^3
- 14.4 KW | <135 ft^2 | 630-950 ft^3
- 21.0 KW | <180 ft^2 | 720-1270 ft^3
- 24.0 KW | <220 ft^2 | 1120-1550 ft^3
- 29.0 KW | <285 ft^2 | 1300-2000 ft^3