FAQs: Sauna Heater Questions Answered

Quick formula to determine the right sauna heater for your space

Our Rule of thumb: Sauna’s Cubic feet / 50 = Sauna Heater Power Needed

So … multiply your sauna’s Length x Width x Height (in feet) to calculate the cubic footage of your heat sauna, and then divide by 50.

E.g. a 5′ x 8′ x 6’6″ sauna is 260 cubic feet / 50 = 5.2 and then round up to the next best heater. So the minimum is 5.2 kW to heat this sauna. Some economical choices here would be the Polar HMR 60 (6kW).

And the Finlandia Sauna Heaters, see chart.

Ladle water on sauna rocks produces a wonderful steam and humidifies your sauna session

All sauna heaters (wood-fired, gas and electric) are designed to enjoy a traditional Finnish steamy sauna experience. It is NOT uncommon for some water to exit the bottom of wall-mounted sauna heaters.

Generally a few splashes of water with your ladle is enough to create a good steam

A few pointers

• Wait until the rocks are actually hot. Flick a few drops first. Water should burst in steam instantly.
• Drizzle water with a ladle, never use your hand! Steam is very hot so careful when near the heater
• Do NOT dump water on the rocks. Electrical sauna heaters are NOT made to be overloaded with water. This is an electrical hazard potentially
• Add several drops of eucalyptus oil to the water to open your lungs and pores.
• Do NOT put eucalyptus oil directly onto the rocks or any other essential oil — they are volatile oils and will ignite when hot.

Keep healthy in your steamy sauna

• Also consider the Hukka Sauna Heater Humidifier for a steady release of light steam to humidify your sauna session
• Also see our article on How to Take a Sauna

Mount Sauna Heater 23″ Off the Floor

Mount my sauna heater instructions

ALLOWS CHECK YOUR SAUNA INSTALLATION INSTRUCTIONS FOR MOUNTING HEIGHT

At right is an exposed sauna wall showing blocking to mount the sauna heater and the intake vent. This is our method for most wall-mounted sauna heaters with 50 lbs of rocks

• Add blocking between your studs, so it’s ready for your installer or electrician to hang the sauna heater on the wall.
  NOTE: IF your sauna is a DROP 4.5, 7.5o 9 OR a Spirit 6 or 8 weighing about 150 lbs., consider doubling the studs!
• Below the heater blocking is the intake vent opening. It sits right on the bottom plate of the wall. So very close to your hard floor. Generally, we make a 4×6″ vent opening IF the heater is 8kW or less, and 6×8″ vent opening if 9kW or bigger
• The intake vent does NOT need to be under the heater. It can be within 3 feet. In small saunas ≤ 4×6, you can also vent under the door (ie., the gap)

Later the sauna wall will be filled with R-13 insulation — excepting for the vent opening! Air will flow through the intake vent and into the sauna. The exit vent allows some air to exit the sauna. We cover the exterior of the vent with a grill and the intake with a sliding door.

Sauna heater installation / Hanging a wall-mounted sauna heater

Set your heater’s top mounting nuts at 23 inches off the hard floor (tile, cement, linoleum, etc.). This should leave between 6 ½–8″ from the hard floor to the bottom of the heater’s shroud.

Sauna Venting | We get these questions a lot:

• Can I vent my sauna heat back into my house?
• Or should I vent the sauna to the outside?

It is best to vent the sauna heat back inside the house rather than to the outdoors. Why?

• The main reason is that the barometric pressure outside is often different than indoors and this can create reverse flow bringing air from the outside in back through the exit vent. Also, you always want to minimize penetrations to the outdoors – it’s just more labor.
• Though it might seem like a great way to add heat to your house, a sauna will add very little positive heat to your home as by design; it is meant to heat a small enclosed space and contain that heat.
• Also FYI, the sauna will not add any significant moisture to the adjoining air space. Even when you ladle water over the sauna heater rocks you add very little actual humidity to the air. Saunas provide very dry air. The added humidity of a sauna ranges from 10-35%.

Most importantly, the air coming into the sauna through the intake opening should be fresh and cooler than the heated sauna air

Fresh air also affects the sauna heater’s thermostat and high limit sensors. Otherwise, the sauna heater may sense that the room is prematurely hot and thus shut the heater down before the desired temperature is reached. Fresh air air has slightly more oxygen but do not be concerned with oxygen levels as the sauna rooms are no where near air tight.

Many saunas do just fine with a wide gap (about 1″) at the bottom of the door serving as the intake vent too. If you’re sauna is in an out building though, careful as small critters may find the warmth and shelter an inviting place to nest or warm up.

We use sliders to control airflow and grills to cover the vents

The cedar grills are beautiful, decorative and you can just as easily match heat registers in your house to the same affect. Sliders are important to control air flow. Many leave their intake vent fully open all the time and prefer a grill to cover the interior side of the intake vent ensuring constant intake air flow.

Vents and grills do not include hardware as customers have different size nail guns or preferences on screws. We use 1 ½” galvanized (or stainless) finish nails.

Air flow is very important for the sauna heater appliance

Your sauna appliance needs fresh cooler air AND so do you! It ensures the air in the sauna does NOT get stuffy, especially as more bathers enter. So … 6 ½–8″ from the hard floor is plenty of space for the sauna heater to pull fresh cool air through through the intake vent AND some hot air will leave out the exit vent (up top, about 4-6″ from the ceiling on the wall) and fresh air with more oxygen can enter. The intake vent will be covered with this 4×6″ Sliding Door Sauna Vent Cover on the inside. (NOTE: bigger heaters > 8kW should get the bigger 6×8″ Sliding Door Sauna Vent Cover.)  And on the outside, you’ll cover the vent with this exterior sauna vent grill.

First Run | Start my sauna heater for the first time

Yes, we do recommend starting any sauna heater with the sauna door open for about 30 minutes max.

This is to burn off any residual chemicals used in the manufacture of the sauna heater elements or housing.

If you go over 30 minutes you are likely to trip the “over-limit” circuit of an electrical sauna. This means your heater has a way to protect itself from working too hard and burning itself out – good design.

My first time doing this, I let my Finlandia FLB 80 sauna heater go for 45 minutes. The internal sauna room temperature was 120°F with the sauna door open! Since it automatically shuts itself off, it may require pressing the reset button on the very bottom of the heater

Sauna heaters types and heat sources

There are electrical saunas, combination wet/dry sauna heaters, natural gas or propane sauna heaters, wood burning sauna heaters, infrared sauna light, infrared emitters.

Specifically powered by:

• GAS — Natural or Propane Gas sauna heaters are larger and are more expensive than wood or electric heaters. Most gas heaters are installed in a 7’x8′ room or larger and must install the heater on an outside wall.
• WOOD FIRED — Most wood burning sauna heaters are installed outdoors. Installation is much like a fireplace or wood stove. Options for wood heaters include water jackets and shower plumb in options that heat water.
• ELECTRIC HEATER — The majority are electric sauna heater (90%) and require typically 30 or 40 AMP dedicated circuit for residential applications. We estimate the cost per usage for an electric sauna at $5-$10/mo.
• INFRARED — Infrared sauna therapy lights provide the full spectrum of light frequencies: near, middle and far infrared wave lengths. The entire infrared spectrum is compatible with cellular processes. Most importantly these lights produce NO electromagnetic field!

Sensor is cutting out before the sauna heater is up to temperature

The first thing to check is your venting set up properly? 

Without correct venting the sensor will get prematurely hot. See our venting FAQ

An easy way to test the sensor is to hang a cold cloth over the sensor just for experiment sake and see if it gets hotter. It usually does.

How to adjust sensor in the sauna?

Use a piece of wood holding the sensor to experiment with the best height for the sensor.

Two ways to adjust the sensor …

If you can pull out a little wire to lower it, do so. You can use a piece of trim with a channel cut into it (as shown below) to cover any exposed wire.

In the same way if the control is on the sauna wall you can drill a hole directly through the back of the control and lead a new sensor and wire through that and use the same piece of trim with channel to run that sensor to a height that works for your desired temperature.

This piece of trim can be made from a 1×2” and a table or skill saw to cut the channel. Run the trim from floor to ceiling, that way it looks good. Daddo’d out 1×2 trim for easy sensor replacement and adjustments. If the sensor has had water poured over it by users, it can go bad.

Some will build an additional wood cover that is opened at the bottom (this still allows hot air the surround the sensor so it works as designed) but keeps the water off the sensor. To test the sensor you can use a multimeter set to The OMS setting, place the multimeter probes into the small terminal strip on the thermostat where the sensor wires connect (this creates some resistance required), turn the heater on and if it works, that determines that the sensor is bad.

If the heater does not work through this process it is another component (most likely the thermostat). In a commercial setting where the bathers have access to the thermostat on the control, mistreatment of this can damage the potentiometer and cause random performance conditions. This requires that the thermostat be replaced.