Thermalution Battery Powered, Heated Undershirt: A Product Review

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Deep South Divers

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Short story: Seriously rocks. Five stars. You need one. No, you can not have mine.

The details: I am not related to Thermalution or the company that sells them here on the East Coast of the 'States (http://www.heatedwetsuits.com) in any way, but I might decide to be after diving this thing today.

I received my Thermalution yesterday via FedEx... But not until I was already out of the water from the day's work (I'm a commercial diver and dive most days). I had a dive club (http://www.BeaufortDiveClub.com – my company’s recreational affiliate) meeting to attend, so I unboxed the shirt, assembled the batteries and such, and wore it under my T-shirt to the meeting.

On the way there I tested the shirt. The controller was on a “leash” coil cord and extended over my right shoulder and draped across my chest. When I held the spring-loaded toggle switch to the “ON” position for a second, the green LED lamp illuminated and told me that the shirt’s twin heaters on my back were on. A minute later I could feel an amazing amount of heat coming across my back. It was like having a heated seat back in my truck… Except on steroids. The effectiveness of this system was unbelievable. Not what I expected at all. The manufacturer claims more than two hours of battery life in this position.

Tapping the controller’s momentary switch to the next position (yellow LED), was too hot for my tastes, sandwiched between the truck’s seat back and my bare skin. Another tap got me a red LED… Apparently representing the primary colors in Hades. The manufacturer claims a one-hour runtime at this level, and says that the shirt can generate temperatures around 140 degrees! Clearly too hot for the truck, but how would it work underwater? I didn’t have long to find out.

The next morning, after an overnight charge of the shirt’s batteries, I wore it to work. Air temperatures hovered around 52 degrees Fahrenheit, with a water temperature of about 46. Being a commercial diver in February sucks.

I dive both wet and dry. This season I used drysuits made by SANTI and Northern Diver, with undergarments by DUI, SANTI, Fourth Element, and UnderArmour. My wetsuits are made by Henderson and O’Neill and range from 3mm to 7mm. For commercial diving, I prefer to dive wet, and today would be no exception. I was diving a Henderson 7mm one-piece jumpsuit, ScubaPro booties (5mm), NeoSport bibbed hood (5mm) and NeoSport 3mm gloves under my work gloves.

The suit was still wet from the previous day’s diving (as it always is), so I turned on the Thermalution (low setting) before sliding the cold suit on. I was donning before I could feel any heat from the shirt, but I did notice that the back of the suit seemed much warmer than the legs and hips as I donned. I was surprised to find that the twin batteries in the shirt just aft of my armpits were not even noticeable… I figured for sure that they’d be in the way. Ditto with the wires. I thought I’d have to spend some time donning the suit and being careful not to pull unnecessarily on the wiring in the shirt, but it all seemed pretty solid and unobtrusive. Frankly, I was surprised.

I donned my hood, thinking that the wire sticking out of the back of the neck-hole of my wetsuit would be a problem and interfere with the hood. Not at all. Even my over-the-head don of my scuba rig didn’t interfere with the controller wires.

Before giant-striding into the water, I turned the shirt up to HIGH. I do this every day, and know to expect a flood of water through the back-mounted zipper of the wetsuit. I figured I’d turn the shirt down if it got too hot.

We all know that feeling… The water seeps in for the first time. Only… This time it was like a cool trickle, not a bone-chilling spine-shrinking breath-taker. As the water flowed into the suit (which was already wet – that always seems to help some), it flowed past the heating elements in the shirt and warmed up before striking my bare skin. Nice!

20 minutes into the dive, I was toasty. Like diving during the summer. I didn’t have a thermometer on my rig, so I figured that I just happened to be diving in an area that was maybe warmer than at yesterday’s dive site. Weird. After all, this couldn’t be the shirt… I mean, my hands and feet were warm, my face (not covered) felt fine, and in general, except for the thick wetsuit, I could have been doing a summer dive. Wet. In the 40’s.

Of course, the only difference was the shirt… And these two, seemingly-too-small heating elements on my back along my spine, sandwiched between my skin and 7mm of neoprene – with a backplate and wing pressing on them. To test the theory, I turned the shirt off and waited for the cold to arrive.

20 minutes later, I could feel a chill beginning to envelop me, but just barely. It was taking a lot longer than I expected to cool off and feel any cold at all. Surprised, I figured that I’d chosen a bad day to test this shirt… ‘Cause the water simply wasn’t cold enough.

I turned the shirt back on, noticing that I’d been dragging the controller through a bit of mud and muck all through the dive. It seemed “crunchy” in my hand, and I was unimpressed with the quality of the controller. A good shake underwater got it to clear out easily, but I could see this becoming an issue at some point unless you tuck it away.

Over the next 20-30 minutes or so I tried switching the shirt from LOW to MED to HIGH several times. I couldn’t honestly feel a difference. In fact, I couldn’t honestly feel a difference between the shirt off or the shirt on… Clearly I had picked way too warm of a day to really test this thing.

Exiting the water and doffing gear and tools and such, I noted that, for the first time in probably my entire dive career, I really didn’t want to get out of the water. Normally, commercial divers look forward to finishing the job. After an hour or two of work, we are rewarded with sun and air and warmth and finally getting some of the cumbersome gear off. We look forward to being able to chill out and breathe for a little bit, and the pressures of work can subside for a little while. Well… I didn’t want to get out of the water. The sun was shining through the surface, the water was winter-coldwater-clear, and I was totally comfortable in a weightless environment. “Ahh, yes,” I thought… “This is why I dive for a living.” What a beautiful, gorgeous dive on a gorgeous day.

Not wanting to return to the world of cell phones and gravity, I doffed my fins, climbed the ladder, and chicken-winged out of my rig. Tools hit the dock and I removed my mask and gloves. I pulled on my hood and popped it off and stood there for a moment, realizing just how freakin’ cold it was outside.

The sun was shining, but the wind was whipping and 50 degrees bit at my ears just enough to let me know it was there. I doffed my booties and that’s when I really realized what was going on.

My boots were steaming. An hour or an hour and a half dive in a wetsuit, and my boots were steaming.

I pulled at my back zipper and let my shoulders test the air. Yep, a chill bit at them too. And when I turned the hose on to rinse off, I realized just how freakin’ cold everything was. Holy Mother of God cold.

How do I put this to accurately describe what I had been experiencing? I had basically been working in a Jacuzzi the entire dive. Inside that suit, submerged just a few feet below the water’s surface, I basically had been cocooned in bathwater… Probably surprisingly close to 98.6 degrees. Those little heating elements had totally warmed the entire layer of water between the wetsuit and me. I was totally faked out by this and believed it to be pretty much a summer dive. Warmer, actually.

I’ve been in diving a long time… And every year some manufacturer somewhere comes along with some product that claims to totally revolutionize scuba diving. I’ve seen many come and go… And in some cases, they actually use the term “revolution” in their company name. Silly, right? The problem is… We’ve all seen this so many times that we’re totally numb to it.

Well… Let me tell you… This Thermalution is a very serious revolution. Really. This changes everything. I am shocked and thrilled and in awe that this simple product can be so effective and change so much.

What’s even cooler is that the shirt can be worn under anything. Want to dive wet? You can use this. Dry? You can use this. Under your ski jacket on the slopes? Yep. At your kid’s soccer game? You got it. This is a very cool product!

For me, warmth isn’t about luxury… It’s a safety issue. I have been so cold at my job that my hands stop working and I can’t think logically anymore. Over the years, I’ve learned to simply deal with it and figured out how to work with these handicaps. Sad, but true… Such is the plight of someone that dives for their paycheck. “Comfort” isn’t the issue… Learning how far you can go into hypothermia and still work is. It’s just part of the job.

This… This changes everything.

A glowing review? Well… Yes. But that’s not to say that the product is perfect. The aft-armpit-mounted batteries and wired controller over the shoulder gives the shirt all kinds of flexibility in application… You could literally use it anywhere and in any way. If it were up to me, though, I’d mount the heating wires inside of a wetsuit and externally plug the wetsuit into a can from a can light… And have that on my backplate and wing. The controller could live on the can’s lid… And in something other than a plastic slider switch. The battery would be ONE battery, not two, and it’d be can-light sized, promising a run time of 10-20 hours or more, not two… That way, I wouldn’t have to charge it every day. But of course, there’s issues with that whole application, and it would only work in that suit that the wires were installed in (which I replace every few months, so this idea sounds expensive) and only for diving. I couldn’t wear the shirt, for example, to an oyster roast/shrimp boil like I am this afternoon.

More criticism: The shirt itself is inexpensive nylon, not quick-drying poly like an UnderArmour shirt, and takes too long to dry. And while the wiring seemed very solid, I hate that it’s so obvious and kinda stiff in those areas. With the shirt on, I could not tell they (or the batteries) were there – hinting at the excellent design – but with today’s conductive fabrics, it seems there would be a simpler, more integrated solution than wires in a shirt.

…Which, by the way, leads me to another criticism… The price. With a $20 controller, a $20 shirt, and maybe $40 worth of batteries and wires, I’m not sure why the shirt costs $400-$700 depending on what features you get. It’s not like it uses any special and expensive conductive fabrics. It’s basically a pair of waterproof, very efficient and impressive heating pads with two cell phone batteries sewn into a false-UnderArmour shirt.

…But those are small criticisms, probably addressed by time and generations of improvements to undergarments such as this.

…For now, I will say this: Diving a battery-powered, heated undershirt is literally a revolution. It changes everything. And frankly, it's totally worth the price. It's that good.

…And yes, you need one.
 
How would you use it under a drysuit? Would you just set the controller to the heat position you desire and then seal the controller into the suit with you?
 
How would you use it under a drysuit? Would you just set the controller to the heat position you desire and then seal the controller into the suit with you?

Good question!

Sure, you could do that, but there's a wireless controller option. That model has an extended battery, too.
 
Good question!

Sure, you could do that, but there's a wireless controller option. That model has an extended battery, too.


Just saw this one. Wow $750? I would love to try one but that price is hard to justify.
 
My thoughts exactly.

Totally worth it though. Wait 'til you try it. It's AMAZING.

DUI is asking $3k for their Blue Heat system, which is similar but can not be used under a wetsuit.
 
You can't go by DUI there off there rocker with there prices. You can get into a Santi for around $1700, still a far cry from $750 though. I don't like the two year life span of the controller due to the non replaceable battery. If they had a demo program I would probably end up purchasing one but need to know the price of the controller when the battery dies, hopefully they will have a trade in program by the time it becomes an issue.
 
You can't go by DUI there off there rocker with there prices.

I couldn't agree more... And I'm on their "Key Man" program because of our TV show and get my DUI stuff at a discount of almost 50%. It's still outlandishly priced. Don't get me wrong... I love the company and have a lot of their stuff... It's just that their prices seem to be totally out of the supply and demand curves.

You can get into a Santi for around $1700, still a far cry from $750 though.

I'm not sure what that has to do with a heated shirt. I have two SANTI drysuits (ESPACE and ELITE) and two SANTI undergarments (BZ200 and BZ400, with BZ200 socks) and am also on the "Key Man" program with SANTI.

Correct me if I'm wrong, but it seems that you're saying, "Why buy a heated shirt for your wetsuit when you can dive dry?" Well... I dive both wet and dry and there's a lot of reasons to dive one way and not the other... I don't always dive dry in the cold, as I mentioned above. But a heated undershirt has nothing to do with diving dry or wet because it works well for both applications.

In both applications, the shirt keeps the diver warm. At the very least, it enables the diver to dive with a lot less exposure protection. A diver diving a BZ400 or XM450 can now dive with a BZ200 or XM250 or even a Polartec fleece. Wet, a diver can dive a 5 mil jumpsuit where he would have dived a 7mil Farmer John. In all of these cases, the diver needs less weight, enjoys less bulk, enjoys more flexibility, and enjoys an easier, simpler dive.

In fact, a diver equipped with a heated shirt now has the ability to control his temperature on the fly. For example, a drysuit diver sitting on the boat in the sun on a 50 degree day in an XM450 COOKS and is only comfortable in the water. The same drysuit diver equipped with a Polartec fleece and a heated shirt can turn his heater on when he splashes, and turn it off if he gets hot. The same goes for a working diver, like in our case... A diver in decompression with no stress is a lot colder than a diver working hard to remove a 1200 pound prop and fighting a 2-knot current. The heated undershirt diver - whether he's diving wet or dry - can select his comfort level "on the fly." The result truly is revolutionary, in my opinion.

I don't like the two year life span of the controller due to the non replaceable battery. If they had a demo program I would probably end up purchasing one but need to know the price of the controller when the battery dies, hopefully they will have a trade in program by the time it becomes an issue.

I agree with you that the system could use some improvements, and the quality and/or the method of controlling the shirt seems to be a good place to start... Which is why I mentioned the issue in my Product Review above. But I am so blown away by the overall concept of having a powered, heated undergarment - and how great it was - that I am willing to overlook this issue at the moment. I am sure that the next generation of power heated shirts will improve the controller. But electing to not enjoy a heater in your suit because you don't like the controller seems short-sighted to me. It really was that great.

---------- Post added March 2nd, 2014 at 12:41 PM ----------

Here's another "big picture" approach on the whole thing, as it pertains to your interest in the cost:

Let's say that you want to go diving in 45 degree water.

Diver A... Drysuit diver with no heat. (Tried and true method). Here's his investment:

1. Drysuit: (Let's say we do the SANTI you mentioned and not one of the $3k-$6k DUIs.) $1700.
2. Undergarment: $600
3. New LP hose, installed: $40
4. Drysuit Diver course: $150.
5. Additional lead on rig: $40.
6. New fins to fit boots: $? (Some need it, some don't.)

Total: $2530.

Diver B... Wetsuit diver with a new Thermalution:

1. 7mil Pinnacle or O'Neill wetsuit: $500. (Many divers already have this.)
2. Thermalution Battery Operated, Heated undershirt for wetsuit: $500.

Total investment: $1000.

The argument of cost doesn't seem to work. And of course, the wetsuit diver is diving a wetsuit and doesn't have the bulk, weight, flexibility issues, and finicky-ness of a drysuit to contend with. If a wetsuit diver holes his wetsuit, for example, he's not stuck aborting the dive and sending the suit back for expensive repairs.

The wetsuit diver also isn't dealing with squeeze, management of the suit's airspace, a moving bubble in the suit, condom caths, and the like.

...But this scenario assumes that there's two "sides" to diving... Wet or dry, and a comparison between the two. The fact is, a heated shirt works regardless of what type of suit it's under, so the debate seems moot.
 
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I think this is a very good solution for wetsuits but not for dry suits.

I would prefer external battery to be used with drysuits / I would not recommend to place any battery next to my skin w/o possibility to disconnect it in case of failure.
 
My Wife Sandra has one of these Thermalution Heated Undergarments......She uses a dry suit for the coldest winter months, ( we live in Palm Beach, Florida where water gets to as low as 69 or 70 in Jan/Feb), and then switches to a wet suit.....the Heated Undergarment, makes the wetsuit work for Sandra on 5 and 6 hour long ( turning it on a off a few times ) dives at the BHB Marine Park--where even in 78 degree water the macro motion nature of the dive would keep many divers in a Dry suit. Except, we hate Dry suits....Her TLS 350, custom cut, still has so much drag that even on a macro dive, the suit is massively limiting. At tidal changes at BHB, which you are in for when you do 6 hour long dives, has the current blasting over her fast enough so even if she lies on the bottom, the suit catches water and begins to try and roll her over.....whereas the wetsuit feels relatively "invisible" to the current, and movement at the BHB is effortless. And of course, the effort of getting around in open ocean on charter dives, is drastically less with the wetsuit.

With this new technology of the Heated undergarment, I would never consider a Drysuit myself--except I suppose for deep tech dives where after 200 feet deep, the wetsuit has become so thin from pressure, that it has no real insulation left to hold in the heat from the Thermalution shirt....I like being in a slick wetsuit, where I can make a big frog kick or big single flutter, and then glide 8 to 10 feet--versus maybe the 6 inches of glide you can get with a dry suit.

I like being slick enough so that pretty much any current can be ignored--something I can do with a wetsuit and Thermalution, and something I CAN'T DO when I wear my own TLS 350 ( which I got 4 years ago before I knew of Thermalution).
Sandra needs the bottom time for here photography....here is a look at what she gets on 5 and 6 hour dives :) www.facebook.com/WILD.DIVING
 
+1 with Dan.

We have both wetsuits and drysuits. We only break out the drysuits when the water is still (when the drag of a drysuit is not an issue), fresh (we find the weighting in salt water too much), and we are able to maintain a prone position (so we can control the suit's airspace properly). Even then, our divers don't like them much, as they tend to restrict movement due to "shrink wrapping." In short, drysuits are a pain in the neck. There's also the obvious expense and the fact that if you hole one, you're in for not having your suit for a while - and paying yet more money - to send it off for repairs. This is a serious issue for the working diver trying to earn a paycheck.

...But we still have them because being in a drysuit means, for the most part, that you're DRY. This allows you to use a variety of undergarments, all of which will keep you warmer than any wetsuit... At least, an unheated one... And not only does this mean longer, safer, more comfortable dives, but it means that when you get out of the water, you're DRY.

Don't believe those that claim that it's easier to don and doff a drysuit, though... Simply untrue. A wetsuit simply peels off and slides on... A drysuit does the same only AFTER you've also donned or doffed your undergarment, UnderArmour, condom cath, or whatever else it is that you're wearing. Some of the systems are three and four layers thick!

Historically, the only comparative downfall of wetsuits is that they can't keep you as warm as a drysuit. There's two reasons for this... One, is that you're wet beneath the suit... The other is because it compresses with depth - that is, you lose loft and therefore insulation as you go deeper.

A heated undershirt - or wet undergarment (whatever you want to call it) - solves this issue.

The only advantage to a drysuit at this point is the fact that you're dry when you get out of the water... And that's a tough one to call an "advantage" for us. Have you ever tried to keep something dry on a rocking boat? What if it's raining? Our working dive sites are typically very wet and muddy and often covered in fuel or other nastiness. We often tell our divers to not take anything to the dive site that they don't want to get wet... Which includes phones, dry clothes, and towels. Leave those in the truck. Drybags? Just don't.

In the next month or so we're going to be installing a tankless hot water heater in one of our trucks. So long as we have a working garden hose at the dive site, we're good. Now being wet when you get out isn't an issue either.

Many commercial divers use hot water suits (some purpose-specific, some just a hotwater hose down a wetsuit) if they're diving an umbilical. That is... If they're already on hookah with an umbilical that's supplying them breathing gas, com systems, and tethers, they often just opt to pipe hot water down to flow in their suit anyway.

Unfortunately, this doesn't work for divers on scuba. System's pretty pricey, too, and takes a topside crew to operate.

The heated undershirt is a fantastic option.

We're currently moving towards using 5mil (Pinnacle and O'Neill - high quality, fitted, sealed suits with very little water exchange) one-piece wetsuits and Thermalutions for diving as low as in the 40's. This makes us slick, flexible, capable, light (a lot of us don't need additional lead at all), and warm during all of our dives, even those that last all day. Heated freshwater when changing tanks and batteries.

I'm working on retrofitting one of our LiIon canister lights to a Thermalution for all-day power. And just like an unmodified Thermalution, a diver will be able to use it under either a wetsuit or a drysuit.

I think this is a very good solution for wetsuits but not for dry suits.

I would prefer external battery to be used with drysuits / I would not recommend to place any battery next to my skin w/o possibility to disconnect it in case of failure.

I'm not going to tell you that a battery could not possibly overheat and/or cause an issue, because I have heard of it happening... But I will tell you that these batteries use the same LiIon technology that's in a pacemaker. If it's safe enough to use internally, I have confidence in using it in my drysuits.

This whole discussion's got me thinking that I need to invent a fitted, taped wetsuit in 3mm and 5mm with a TiZip and heating elements throughout. I could sell them in different grades - some with twin back-mounted heating elements only, and others with elements in the front and even on the biceps and quads. Power would be either a chest-mounted small battery or a can from a can light. Controls on the battery pack.

There'd be no longer "wetsuits" and "drysuits" and even the marketing-jargon "semidry suits." There'd now be "heated suits."

...Meanwhile, this Thermalution rocks. Changes everything.
 
https://www.shearwater.com/products/peregrine/

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