Plunge Sauna Review: A Plunge into Disappointment?

Could this be real?

At first glance, the Plunge Sauna looks like a high school design student redesigned a cheap Chinese infrared sauna.  It even uses hemlock.

We reserve our judgment and are happy to see the cold plungers be exposed to the other half of contrast therapy. The sauna cold plunge routine is truly where the magic happens.

But is the Plunge crowd getting a good sauna experience or a cheap gimmick that won’t perform well or last?

Ultimately time will tell. We have some doubts, but what’s really crazy is comparing the Plunge Sauna and price with high-end European sauna kits.  Scroll to the end of this post to see what we mean.

What they got right

Heater

The HUUM DROP is the right choice for this sauna, at least for most people. While we prefer to let customers choose, HUUM is the only heater brand in North America that is designed to reach temps up to 230°F.  Keep in mind, that max temperature is only reached at the temperature sensor location.

So as we’ll see later, this sauna may require you to push temperatures well into the 200°s to reach a decent temperature on the bench.  By the way, the research says anything over 180°F delivers the health benefits we’re after.  

Like all HUUM heaters, the DROP has a large stone capacity which is critical for such a small sauna. The thermal mass ‘mellows’ the heat so it’s not so harsh when heating up.

Plunge delivers a true sauna experience with good heat, steam, and stones.  

Wi-Fi Enabled UKU and Protector

HUUM’s UKU controller is ideal for getting that sauna up to temperature using your phone, or setting a schedule. While the sauna will heat up faster, it’s a better experience to give it a full hour to let the walls and rocks fully heat up. At this point, the heater will hardly be doing any work and you’ll have plenty of steam potential banked in the rocks.

The UKU controller should be protected from direct rain and sunlight, and the Plunge Sauna has a beautiful wood box for it.

Ventilation

We were early to point out some design flaws on the Plunge Sauna, and happy to see some of these problems were addressed.

Initially there was no sign of an exhaust vent on the sauna, which is important for air flow, heat distribution, and maintaining safe CO2 levels in the sauna.

We are happy to see that proper exhaust vents have been placed below the bench, which will improve performance.

Foldup Benches

The foldup benches are very useful if planning on using the sauna for stretching out. The is a nice, simple design and fully conceals the benches against the walls. However, if you want decent temperatures at floor level, and more control over the sauna climate then a Saunum Air Circulating Heater is highly recommended. Unfortunately they are not compatible with the Plunge Sauna.

Missed Opportunities

While we hope we are wrong, the Plunge Sauna misses some important sauna design principles, and we feel sad that so many sauna owners may never experience quality heat and steam.

We first became suspicious when we watched Jesse Itzler and The Sauna Papi bike across America with two saunas. Guess which one never got used?

At a price range of $10,990 – $11,990, Plunge Sauna’s fundamental flaw is the shape.

The product seems to neglect the basic understanding of sauna principles: the heat generated by the sauna stove needs to be evenly distributed for the occupant’s comfort. This is accomplished by promoting a convective loop.

We want heat to rise at the sauna heater, then work its way across the ceiling, and then fall down the opposite cooler wall.

The most important thing to remember here is that heat rises.

Ceiling Slant Promotes Stale Air

Plungers may be more preoccupied with dodging the uncomfortably hot ceiling than enjoying a relaxing sweat session.

As the design currently stands, the heat will be drawn upwards, settling in the high pocket of the sauna and then down the cool glass on the opposite wall from the bathers.

Even with proper vents, the odd shape of the sauna does not allow the air to circulate to the bathers location.

Without a convective loop, the result will likely be uneven sauna temperatures and stale air rich in CO2 and low in oxygen.

So the extreme heat will settle at the ceiling, and guess what? Your head is practically touching it.

Since your head is your personal temperature sensor, you will likely overheat and leave this sauna before your feet warm up at all.

The location of the bather’s head may lead to extreme discomfort due to the significant heat disparity between the sauna’s lower and upper parts, which could negatively affect the sauna experience.

If the ceiling was flat or slanted toward the bather, the heat would rise to the back wall where the benches are and drop down the cooler wall and out the exhaust vent.

That’s the convective loop we’re looking for.

Unfortunately, that just ain’t happening here.

Not Build to Last

Even if you like the funky ‘Cybertruck’ shape, the Plunge Sauna has exposed bolts, uses questionable materials, and plenty of areas for water to infiltrate the structure. We hope we are wrong but would expect these to look rather war-torn in a couple years.

The biggest red flag is an insulated wall with a weather barrier that is not connected together. 

High-end European sauna kits like the Auroom Mira have an air barrier that overlaps each panel and gets tapped together.

That creates another step since the panels cannot ship with exterior siding fully installed, but if the weather barrier is not connected between panels then you simply don’t have one.

Sauna kits with a single layer of wood do not have or need a weather barrier because the wood can dry to the interior and exterior.

The risk here is that humid air will be drawn through the wall panels and into the wall assembly.  If this happens, it won’t take long for the insulation to be degraded and mold to start forming in the wall cavity.

Head (or hat) Will hit Ceiling

As discussed, the sauna bathers head will be at the low end of the sauna, opposite of glass. Plunge pictures show heads almost touching the ceiling.

This is not good for a few reasons. This is how we would design a sauna if we wanted a maximum temperature difference between the head and feet.

We’ve been told it’s also quite annoying and makes it feel claustrophobic.

Due to the design, a sauna hat will be essential because most of the heat is at head level. Sauna hats, including the one sold by Plunge themselves have a ring on top that will annoyingly hit the ceiling even if you are not tall.

Sauna-goers may be more preoccupied with dodging the uncomfortably hot ceiling than enjoying a relaxing sweat session.

Expect Nuisance Trips.

The Plunge Sauna plans on using a NEMA 14-30 socket so users can ‘plug and play.’ Brilliant, but why don’t other saunas use that? Because it requires a GFCI (ground fault protector) that causes the breaker to trip. Sauna heaters, including the HUUM DROP do not recommend a GFCI or any earth leakage fault protection for this reason.

Odd Wood Choices

The Plunge sauna uses incense aromic cedar for exterior and benches. This is not the western red cedar you would expect on a sauna, but Juniper used for cedar chests. It is not known for exterior use and is likely to warp in this role. This is another design choice that we would bet against in the long term.

Are these saunas really built to last? There’s a reason there’s no exterior decking or siding material made out of incense cedar. Again, time will tell.

Big Ugly Visible Power Box

The facepalm-worthy power box is preinstalled so it can’t be hidden behind the sauna. 

Built Their Own App 

HUUM has an excellent app to control the heater from your phone using wi-fi signal.  It works great.  With the Plunge Sauna, you need to control it from Plunge’s cold plunge app, and early report are that it’s glitchy.  We don’t see how this an be reliable with hardware updates pushed from HUUM out of Estonia.  

Plunge Sauna Reviews By Sauna People

We’re not the only ones who are concerned about the Plunge Sauna.  Customer reviews on their own website have mentioned the Wi-Fi app doesn’t work, the pilot holes were too small, and the glass was too thin.

Here’s what sauna designers and builders are saying:

1. Some people find The Plunge Sauna is small and lacking a drain, and ventilation, and they have concerns about its weird ceiling geometry.
2. One person believes it is unlikely that many people would purchase the sauna, describing it as odd and trying too hard.
3. Another individual sees it as a missed opportunity.
4. There are concerns about the Huum wall-hung electric heaters having problems with failing elements, with doubts about whether the issue has been adequately addressed (editors note: they have).
5. The company is criticized for prioritizing looks over functionality. The sloped roof and ends of the sauna are deemed problematic, as they make it difficult to submerge and lie down comfortably fully.
6. The sauna is considered expensive at $9,000 (now more expensive)
7. One person recommends looking into alternative sauna companies.
8. A contributor suggests contacting the nearest Helo or Finnleo dealer for further recommendations. (check below for best alternatives).

We Have Hope

Despite early problems, Plunge did develop one of the most reliable cold plunges on the market.

We expect they’ll make improvements or go back to the drawing board on the sauna as well.  For now, we recommend waiting to see how these hold up.  

Plunge Sauna Alternatives

The biggest takeaway here is that there are better options for less, and world-class saunas from the best European brands little more.

These saunas are likely to last longer, perform better, and give you more options