The best steam shower generator for your home is the model its own manufacturer's sizing rules call for, paired with a control and steam head you will use every day. Sauna Republic carries two brands for residential steam showers, ThermaSol and Mr. Steam, and they size their generators differently. This guide explains both methods, lists the 17 current models, and covers controls, installation and warranties.
Quick answer: a 3 × 4 ft shower with an 8 ft ceiling holds 96 cubic feet. With tile walls, ThermaSol's rules call for the PROIII-140 (8 kW) and Mr. Steam's for the MS150R (6 kW). With marble walls, the ThermaSol answer stays the same and the Mr. Steam answer moves up to the MS225R (7.5 kW). Compare the model each brand recommends for your shower, not cubic-foot ratings across brands.
How to size a steam shower generator
Both manufacturers start from the same measurement: the length, width and height of the enclosure in feet, multiplied together. A 3 × 4 ft shower with an 8 ft ceiling holds 96 cubic feet, and a 4 × 5 ft shower with a 9 ft ceiling holds 180. From there the two brands part ways, and each rates its generators for its own method.
ThermaSol: volume and ceiling height
ThermaSol sizes the PRO Series III on volume alone. Its PRO Series III page states that "wall materials do not affect generator size." Ceiling height does count: for a 9 ft ceiling, ThermaSol says to size up one generator, and for a 10 ft ceiling to size up two or confirm the size with its team. In practice, choose the smallest model whose rating covers your shower's volume, then apply any ceiling step-up.
Mr. Steam: volume adjusted for materials and ceiling height
Mr. Steam's installation manual for its MS and MS Super generators adjusts the volume before you choose a model:
Then choose the model whose range includes the adjusted volume, using the Mr. Steam table further down. The MS and MS Super series cover adjusted volumes up to 482 cubic feet; above that, the MAX series takes over, and we confirm MAX sizing with you before you order.
Three worked examples
Here is how the same three showers size under each brand's rules.
| Shower | Volume | ThermaSol PRO Series III | Mr. Steam |
|---|---|---|---|
| 3 × 4 × 8 ft, tile walls | 96 cu ft | PROIII-140, 8 kW | MS150R, 6 kW (96 cu ft, no adjustment) |
| 3 × 4 × 8 ft, marble walls | 96 cu ft | PROIII-140, 8 kW (walls do not change the size) | MS225R, 7.5 kW (96 + 50% = 144 cu ft) |
| 4 × 5 × 9 ft, tile walls | 180 cu ft | PROIII-395, 11 kW (PROIII-240, plus one size for the 9 ft ceiling) | MS400R, 9 kW (180 + 15% = 207 cu ft) |
The examples show why cubic-foot ratings should not be compared across brands: each manufacturer's ratings assume its own rules. Our steam shower generator size calculator applies each brand's rules to your measurements and names the model for each.
Ceiling over 10 ft, or a result near a model's limit? Mr. Steam's adjustments stop at a 10 ft ceiling, and for a 10 ft ceiling ThermaSol says to size up two generators or confirm the size with its team. Send us your measurements before you order, and a specialist will review the size with you.
ThermaSol PRO Series III
ThermaSol's current residential generator line is the PRO Series III, in seven sizes from 6 to 24 kW. Among the features ThermaSol lists for it:
| Model | Power | Rated shower volume (maximum) |
|---|---|---|
| PROIII-84 | 6 kW | 84 cu ft |
| PROIII-140 | 8 kW | 140 cu ft |
| PROIII-240 | 10 kW | 240 cu ft |
| PROIII-395 | 11 kW | 395 cu ft |
| PROIII-575 | 15 kW | 575 cu ft |
| PROIII-750 | 20 kW | 750 cu ft |
| PROIII-1200 | 24 kW | 1,200 cu ft |
Each rating is the largest shower that model is meant for under ThermaSol's volume-only rule. The PROIII-84, for example, covers showers up to 84 cubic feet, so a 96 cubic foot shower moves up to the PROIII-140.
ThermaSol specifies a 208 to 240 V single-phase supply with a dedicated breaker for PRO Series generators, and says the generator can be installed up to 50 feet from the shower. It lists a SteamVection kit and a stainless steel drain pan as included with the PRO Series III. The control is chosen separately: on each PRO Series III product page, our configurator lets you choose the control, steam head and finish, as described under controls and steam heads.
For the full PRO Series III lineup, the controls and steam heads, installation essentials and warranty terms, see our ThermaSol steam generator buying guide.
Mr. Steam MS, MS Super and MAX
The Mr. Steam generators we carry come in three series: MS (5 to 9 kW), MS Super (10 to 15 kW) and MAX (20 to 30 kW). Mr. Steam lists the United States as their country of origin. For MS and MS Super, the ranges below apply to the adjusted volume from Mr. Steam's installation manual; the MAX ranges come from Mr. Steam's planning guide. Current draw is at 240 V, single phase.
| Model | Series | Power | Volume range | Current draw |
|---|---|---|---|---|
| MS90R | MS | 5 kW | Up to 71 cu ft | 21 A |
| MS150R | MS | 6 kW | 72 to 107 cu ft | 25 A |
| MS225R | MS | 7.5 kW | 108 to 161 cu ft | 32 A |
| MS400R | MS | 9 kW | 162 to 257 cu ft | 38 A |
| MSSUPER1R | MS Super | 10 kW | 258 to 339 cu ft | 42 A |
| MSSUPER2R | MS Super | 12 kW | 340 to 411 cu ft | 50 A |
| MSSUPER3R | MS Super | 15 kW | 412 to 482 cu ft | 63 A |
| MX4R | MAX | 20 kW | 483 to 678 cu ft | 84 A |
| MX5R | MAX | 24 kW | 679 to 822 cu ft | 100 A |
| MX6R | MAX | 30 kW | 823 to 964 cu ft | 125 A |
Choices to make when you order
Mr. Steam bases its wire sizes on copper conductors rated for at least 90°C (194°F) and makes 208 V and three-phase generators on request. For the MS and MS Super series, its installation manual calls for a separate circuit breaker and allows up to 60 feet of insulated steam piping between the generator and the steam room.
Our Mr. Steam steam generator buying guide covers the MS, MS Super and MAX series in more depth, including Express Steam, AutoFlush, the rules that apply only to MAX, and warranty terms.
Not sure which generator fits your shower?
Send us your shower's dimensions, wall material and ceiling height, and a specialist will reply with the model each brand's rules call for and current pricing.
Get PricingThermaSol vs Mr. Steam
The two lines differ in how they size, what comes standard and what is an add-on. Here is how they line up on the points buyers ask about most.
| Feature | ThermaSol PRO Series III | Mr. Steam MS, MS Super and MAX |
|---|---|---|
| Models we carry | 7, from 6 to 24 kW | 10, from 5 to 30 kW |
| Largest model we carry | PROIII-1200, 24 kW, rated to 1,200 cu ft | MX6R, 30 kW, range up to 964 cu ft |
| Sizing rule | Volume only; size up for a 9 or 10 ft ceiling | Volume adjusted for wall material and ceiling height (MS and MS Super manual) |
| Faster start-up | FastStart, a PRO Series III feature | Express Steam, a factory-built version of each model |
| Self-cleaning | PowerFlush, a PRO Series III feature | AutoFlush, an add-on |
| Power supply | 208 to 240 V single phase, dedicated breaker | 240 V single phase as standard; 208 V and three phase on request |
| Generator to shower | Up to 50 ft | Up to 60 ft of insulated steam piping (MS and MS Super) |
| Control and steam head | Control chosen in our configurator; ThermaSol lists a SteamVection kit as included with the generator | Control chosen in our configurator; each control comes with a steam head |
| Generator warranty | Two-year limited in-home warranty, then parts for life with factory service | Limited lifetime: two years of in-home service, parts and labor, then parts for life |
Which one fits your project
For a side-by-side look at sizing, electrical, start-up, controls, installation and warranty, see our full ThermaSol vs Mr. Steam comparison.
For hotels, spas, gyms and short-term rentals, look at commercial generators instead: ThermaSol provides no warranty on residential generators used in those settings. Our commercial steam generator buying guide covers them.
Controls and steam heads
A steam shower needs three components: the generator, a control and a steam head where the steam enters the shower. Both brands sell the generator separately from the control. On every ThermaSol PRO Series III and Mr. Steam generator page, our configurator lets you choose the control, steam head and finish, then sends the build to us for a quote.
ThermaSol controls and steam heads
ThermaSol's controls are the ThermaTouch2 15, ThermaTouch2 10 and ThermaTouch2 7, the SignaTouch (wall-mount or recessed) and the MicroTouch (wall-mount round or recessed square). The steam heads in our configurator are the SteamVection, in round or square, and the No Touch. ThermaSol offers most of its controls and the SteamVection head in 15 finishes; the No Touch comes in polished chrome.
Mr. Steam controls and steam heads
Mr. Steam's controls are the iSteamX and TempoFlex, each with a black or white face, the iTempo in round or square, and the TempoTouch. Each control comes with a steam head, and you can choose the Aroma, the Designer in round or square, or the 16-inch Linear; all three have an aromatherapy reservoir. Mr. Steam offers its controls and steam heads in 13 finishes. If you plan to add essential oils, our guide to using essential oils in a sauna or steam room covers steam rooms as well as saunas.
Our steam shower control and steam head guide compares the controls and steam heads for both brands, including screen sizes, app control and where each must be mounted.
Installation requirements
Plan the electrical and plumbing work before you settle on finishes. The requirements below come from each manufacturer's own documents; a licensed electrician and plumber should confirm them against your local code.
For the full pre-construction checklist from both brands' installation manuals, from the enclosure and generator location to the electrical, plumbing and steam line, see our guide to steam shower installation requirements.
If you are still deciding between a steam room and a sauna, our infrared sauna vs steam room comparison sets out the differences in heat, humidity and installation.
Warranty coverage
ThermaSol
ThermaSol's warranty page gives PRO Series generators a two-year limited in-home warranty. During that period, ThermaSol repairs or replaces parts with manufacturing defects and covers labor up to a standard regional service rate when a ThermaSol agent or a qualified independent technician does the work. After two years, its factory limited warranty replaces defective parts for the life of the product for the original purchaser, with labor performed at the factory; the owner handles removal, reinstallation and shipping to and from the factory in Round Rock, Texas. ThermaSol notes that local in-home service is not guaranteed, and it requires proof of purchase from an authorized reseller to start a claim.
Mr. Steam
Mr. Steam gives its MS, MS Super and MAX generators a limited lifetime warranty in the US and Canada: free in-home service, parts and labor for claims made within two years of purchase, then parts for the life of the generator. Mr. Steam controls and accessories carry a limited two-year warranty.
Sauna Republic is an authorized dealer of both brands.
Financing and HSA/FSA
Financing is available through Shop Pay Installments; our financing page explains the options. Every invoice also includes a "Pay with Truemed" option: click it and Truemed decides whether your purchase qualifies for HSA/FSA funds. Our HSA/FSA page explains how it works.
Frequently asked questions
What size steam generator do I need for a 3 × 4 × 8 ft shower?
That shower holds 96 cubic feet. ThermaSol's rules call for the PROIII-140 (8 kW) whatever the wall material. Mr. Steam's call for the MS150R (6 kW) with tile walls and the MS225R (7.5 kW) with stone or marble walls. Our size calculator runs the numbers for other dimensions.
Does wall material change the generator size?
It depends on the brand. ThermaSol says wall materials do not affect PRO Series III sizing. Mr. Steam's MS and MS Super manual makes no adjustment for ceramic or porcelain tile, adds 50 percent for natural stone, marble, shale, glass block or concrete, and subtracts 40 percent for acrylic or fiberglass.
How does a higher ceiling affect sizing?
ThermaSol says to size up one generator for a 9 ft ceiling, and two for a 10 ft ceiling or to confirm with its team. Mr. Steam's MS and MS Super manual adds 15 percent to the volume for each foot above 8 ft, up to a 10 ft maximum.
Does a steam generator come with a control and steam head?
Not the control. ThermaSol lists a SteamVection kit and a stainless steel drain pan as included with the PRO Series III, and each Mr. Steam control comes with a steam head. On each generator page, our configurator lets you choose the control, steam head and finish.
How far can the generator be from the shower?
ThermaSol says its generator can be installed up to 50 feet from the shower. For MS and MS Super generators, Mr. Steam's sizing allows up to 60 feet of insulated steam piping, with the generator in a closet, vanity cabinet, heated attic or basement, and never inside the steam room or in an unheated attic.
What electrical service does a steam generator need?
A dedicated circuit. ThermaSol specifies a 208 to 240 V single-phase supply with a dedicated breaker. Mr. Steam generators draw from 21 A to 125 A at 240 V depending on the model, and Mr. Steam's MS and MS Super manual calls for a separate circuit breaker. Have a licensed electrician size the circuit before you order.
What is the difference between FastStart and Express Steam?
FastStart is a PRO Series III feature that ThermaSol describes as steam in seconds, not minutes. Express Steam is a factory-built version of each Mr. Steam generator that starts producing steam sooner, so it has to be chosen when the generator is ordered.
Can I use a residential steam generator in a gym, spa or rental?
Check the warranty first. ThermaSol provides no warranty on residential generators used in non-residential settings such as hotels, spas, gyms or short-term rentals. Our commercial steam generator guide covers generators built for those settings.
Get pricing on a ThermaSol or Mr. Steam generator
Send us your shower's dimensions, wall material and ceiling height, and a specialist will confirm the size and reply with current pricing.
Request pricingBrowse all steam shower generators to compare models side by side.
ThermaSol, Mr. Steam and the product and feature names in this guide are trademarks of their respective owners.
