Mr. Steam Steam Generator Buying Guide: MS, MS Super, MAX | Sauna Republic

Steam generator buying guide

Choosing a Mr. Steam steam generator comes down to four things: the model Mr. Steam's sizing rules call for, whether to order the factory-built Express Steam version, the control and steam head, and how the generator will be drained. This guide covers all ten residential models in the MS, MS Super and MAX series, drawing on Mr. Steam's 2025 installation manuals, its planning guide and its product data.

Quick answer: multiply the shower's length, width and height in feet, then apply the MS and MS Super manual's adjustments: none for tile, plus 50 percent for natural stone or marble, minus 40 percent for acrylic or fiberglass, and plus 15 percent per foot of ceiling above 8 ft, up to a 10 ft maximum. A 3 × 4 × 8 ft tiled shower (96 cu ft) calls for the MS150R (6 kW); in marble (144 cu ft after the 50 percent adjustment), the MS225R (7.5 kW). Express Steam must be chosen when you order, and AutoFlush and a drip pan are separate parts.

The three series and ten models

Mr. Steam's product data lists the United States as the country of origin for all ten residential models, and its planning guide states: "All generator models are cULus Listed." The ranges below are adjusted room volumes (see the sizing section) from Mr. Steam's installation manuals, and amps are for 240 V, single phase.

Model	Series	Power	Adjusted volume range	Amps at 240 V, single phase
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

MS series (MS90R to MS400R). 5 to 9 kW. Mr. Steam's planning guide gives the generator alone, without AutoFlush or plumbing features, as 14.5 × 14.75 × 6.75 inches, and water usage runs from 0.67 to 1.2 gallons per 20 minutes of operation.

MS Super series (MSSUPER1R to MSSUPER3R). 10 to 15 kW, 17 × 18.5 × 7.9 inches, and 1.4 to 2 gallons per 20 minutes.

MAX series (MX4R to MX6R). 20 to 30 kW, 25.125 × 20.75 × 7.875 inches (Mr. Steam's 2025 MAX manual), and 2.7 to 4 gallons per 20 minutes, with its own installation rules (see how the MAX series differs).

Larger steam generator standing on a drip pan in a basement utility room with insulated copper steam piping

Sizing a Mr. Steam generator

Mr. Steam's MS and MS Super manual opens its sizing worksheet with this: "Materials of construction, room size and special design features such as large glass areas, all affect the steam generator model selection." The worksheet then runs in four steps:

1. Measure. Multiply length, width and height in feet.

2. Adjust for materials. Ceramic or porcelain tile on cement board or a mortar bed: add 0 percent. Natural marble, stone, shale, glass block or concrete: add 50 percent. Acrylic or fiberglass: subtract 40 percent.

3. Adjust for the ceiling. For each foot above 8 ft, to a maximum of 10 ft, add 15 percent to the volume after the material adjustment.

4. Choose the model. Pick the model whose range includes the total.

The manual also says: "Limit steam room ceiling height to 8 feet. Exceeding 8 feet may require a higher-rated steam generator." The worksheet stops at a 10 ft ceiling and has no line for large glass areas, so send us the details if either applies.

Acrylic or fiberglass? The same page also says to "select next lower-rated MS model" for acrylic or synthetic rooms, without saying whether that adds to the 40 percent reduction, so mention the acrylic or fiberglass walls in your quote request.

Worked examples

Shower	Room volume	Adjustment	Adjusted volume	Model
3 × 4 × 8 ft, tile walls	96 cu ft	None	96 cu ft	MS150R, 6 kW
3 × 4 × 8 ft, marble walls	96 cu ft	Plus 50% for marble	144 cu ft	MS225R, 7.5 kW
4 × 5 × 9 ft, tile walls	180 cu ft	Plus 15% for the 9 ft ceiling	207 cu ft	MS400R, 9 kW
4 × 5 × 9 ft, marble walls	180 cu ft	Plus 50% for marble (270 cu ft), then plus 15% for the ceiling	310.5 cu ft	MSSUPER1R, 10 kW

In the last row, the 15 percent applies after the material adjustment, as the manual specifies. Try your own measurements in our steam shower generator size calculator, and compare ThermaSol's rules in our guide to the best steam shower generators.

Sizing the MAX series

The MAX manual uses the same worksheet lines for tile, natural stone and ceiling height, and its chart continues from 483 to 964 cubic feet. We confirm MAX sizing with you before you order.

Want the size checked first?

Send us your shower's dimensions, wall material and ceiling height, and we will reply with the model Mr. Steam's rules call for and current pricing.

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Express Steam

Express Steam is a factory-built version of each Mr. Steam generator. The MS and MS Super manual explains: "Express Steam generators are equipped with a low power heating element and thermostat to keep the water in the tank warm enough to bring up steam quicker." The same manual adds that installers need no additional wiring or plumbing for it.

Order it up front. The manual calls Express Steam "only available factory installed," so choose it when you order. Mr. Steam's product data lists an Express Steam version of every MS, MS Super and MAX model under its own item number, with the same size and electrical figures as the standard model.

With AutoFlush. Both manuals say AutoFlush drains an Express Steam generator, then refills it with fresh water to begin the pre-heat cycle.

AutoFlush, drip pans and maintenance

Both manuals warn that scale can form inside a generator and cause it to fail, and that the concentration of the impurities behind it is "generally controlled by the water quality and by periodic draining of the generator."

AutoFlush

AutoFlush is an add-on: the MS81500E for MS and MS Super generators and the CT81500 for MAX. Mr. Steam calls it "an automatic self-cleaning system" that flushes the generator's sediment 2 hours after every steam bath. It needs a drain line lower than the AutoFlush assembly, and because the valve may discharge boiling water in a power failure, it must never drain into the steam enclosure or anywhere accidental contact with the drain water may occur. Both manuals recommend AutoFlush in hard water areas "for generator longevity."

Draining by hand

Both manuals say the manual drain valve should be opened fully every 2 months, or more often in hard water areas, after the water has cooled: at least 2 to 3 hours after the control is turned off for MS and MS Super, and at least 8 hours for MAX.

Water quality

Both manuals say the water supply should be tested before installation by "a recognized and reliable water treatment company," and list recommended feedwater limits, including a hardness of 8 to 85 ppm and a pH of 8.0 to 11.4.

Drip pans

Both manuals state: "MrSteam strongly recommends the use of a drip pan in the unlikely event of a plumbing leak." It is a separate part: 103867 for MS and MS Super (25 × 9 × 1 1/2 inches) and 104402 for MAX (33 × 9 × 1 1/2 inches), draining by gravity to an approved drain line. Every Sauna Republic quote for a Mr. Steam generator includes the AutoFlush and drip pan made for its series.

Controls and steam heads

Both manuals say Mr. Steam generators are to be operated with Mr. Steam controls only. Mr. Steam lists its four current controls as compatible with every generator, each comes with a steam head in the same finish, and both are offered in 13 finishes.

Control	Screen	Adjusts	Notable features, as Mr. Steam lists them
iSteamX	7 in waterproof touchscreen	Session time, temperature and clock	Black or white face; automatic pre-heat, custom profiles, Bluetooth audio and passcode protection; solid brass
iTempo, round or square	2 in	Session time and temperature	Flush-mounted; listed as working with the SteamLinx module and app
TempoFlex	2.75 in	Time and temperature, two user presets	Black or white glass face; wireless, with a rechargeable battery designed to hold a charge for up to 6 months, or wired for constant power
TempoTouch	Touch button and temperature arc	Temperature only	Simple on and off; hard-wired directly to the generator

Small round black glass steam shower control with a brushed metal trim ring on a tiled wall

Where the control goes

Inside or outside. The MS and MS Super manual says the controls "can be located inside the steam room or on the outside of the steam room." Outside, a remote temperature probe (part MSTS) must be installed inside the steam room.

Inside the room. 4 to 5 feet above the floor near the bather seating area, on a vertical wall, and not above or near the steam head, since the control has an integral temperature sensor.

Cable. 30 feet as standard and 60 feet at most, run in a dedicated 1 inch conduit away from power lines and hot water or steam piping.

The three steam heads

Every control comes with one of three steam heads, each with an aroma oil reservoir: the 3 inch Aroma, the 3 inch Designer (round or square) and the 16 inch Linear, which Mr. Steam says fits between 2 × 4 studs set 16 inches on center and nearly disappears in the grout line. The manuals place a steam head 6 to 12 inches above the floor (6 inches above a tub's top edge), not within 12 inches of a wall, out of a bather's reach and with its oil well facing up.

Long slim linear steam head mounted low on a tiled steam shower wall, one of the steam head styles offered with a Mr. Steam steam generator

SteamLinx and the configurator

SteamLinx is a Wi-Fi module and mobile app that Mr. Steam says lets you "control your steam shower" from a smartphone or mobile device. Our configurator on each Mr. Steam product page asks for start-up speed, control, face, shape, steam head, add-ons and in-shower extras, then sends the build to us for a quote. Add-ons that wire back to the generator mean opening the wall if you add them later. Our steam shower control and steam head guide compares these options with ThermaSol's.

How the MAX series differs

The MX4R, MX5R and MX6R size the same way for tile, stone and ceiling height, but the MAX manual sets its own installation rules:

Two or more steam heads. "MAX Steam Generators must be installed with two or more steamheads," spaced evenly through the steam room and piped so each receives an equal amount of steam. The manual warns that fewer than two may result in scalding and personal injury. Each Mr. Steam control comes with one steam head, so our MAX quotes add a second steam head in the same style and finish.

Never on a wall. "Do not hang the MAX steam generator on a wall." MS and MS Super generators, by contrast, have keyhole slots for wall mounting.

No vanities or small spaces. Not inside a vanity or other small enclosed spaces, or under the steam room bench, which the manual says may result in elevated temperatures and an inoperable generator. It calls for a room with ventilation as required.

More service space. At least 18 inches on the left side and 21 inches at the top, plus at least 12 inches for the steam piping, drain, AutoFlush, water feed and pressure relief plumbing.

A 1 inch drain. The MAX drain is 1 inch NPT (1/2 inch on MS and MS Super), and the manual says: "Do not connect the generator drain line to an under sink trap."

Installation essentials for MS and MS Super

The MS and MS Super manual says installation and service are for "qualified and licensed electricians and plumbers only." These are planning points, not instructions; our steam shower installation requirements guide sets out both brands' requirements side by side.

Location. As near as practical to the steam room, typically a closet, vanity cabinet, heated attic or basement. Never inside the steam room, outdoors, in an unheated attic or where water could freeze, near flammable or corrosive chemicals, or in high-chlorine areas such as a pool equipment room.

Mounting and clearance. Upright only, on a solid, level surface or wall-mounted on the keyhole slots with supports underneath. At least 12 inches at both ends and the top, zero clearance to combustibles, and an ambient temperature not exceeding 113°F (45°C).

Electrical. A separate circuit breaker, a power supply disconnect within sight of the generator (or one that can be locked in the open position), and minimum 90°C, 300 V rated insulated copper conductors. Have a licensed electrician size the wire from the manual's chart and local code.

Water. A cold water line to the 3/8 inch inlet, with a shut-off valve and a recommended strainer upstream, and brass or rigid copper piping with unions; the feed line may be flexible copper tubing, braided hose, PVC or PEX where local codes permit. Feed pressure of 15 to 20 psi is recommended to reduce operating noise.

Drain and safety valve. The 1/2 inch drain should not share an under-sink trap unless the generator is mounted higher than the sink, and must never empty into the steam enclosure or anywhere accidental contact with drain water may occur, or connect to the safety valve line or the steam piping. The safety valve outlet is never fitted with a shut-off valve or a plug.

Steam line. 3/4 inch brass pipe or copper tubing, insulated with material rated 212°F or higher and pitched 1/4 inch per foot toward the steam head or the generator, with no valves. The sizing chart allows for up to 60 feet of insulated steam piping; beyond that, Mr. Steam says to consult the factory.

Warranty coverage

Mr. Steam lists a limited lifetime warranty, for the US and Canada, on its residential generators. For a claim made within 2 years of purchase, Mr. Steam "will provide free in-home warranty service, parts and labor"; after 2 years, it "will provide a lifetime warranty on parts." Controls and accessories, AutoFlush included, carry a limited 2-year warranty.

Residential use only. Both manuals say their series "are for residential use only" and that commercial or other nonresidential applications void the warranty. For those projects, see our commercial steam generator buying guide.

Exclusions. The MS and MS Super manual excludes malfunction due to "power spikes, lightning, fire, freezing or flooding," and both manuals say altering or modifying any Mr. Steam product voids the warranty.

Sauna Republic is an authorized dealer of both Mr. Steam and ThermaSol.

Which Mr. Steam fits your project

Each answer comes from Mr. Steam's own rules and listings.

Tile, stone or a tall ceiling. Run the worksheet; the worked examples cover all three.

Over 482 adjusted cubic feet. A MAX, with two or more steam heads, never on a wall or in a vanity. We confirm MAX sizing with you.

A generator in a vanity or closet. An MS or MS Super, whose manual lists both as typical locations.

Hard water. Test the water and add AutoFlush.

A quicker start. The Express Steam version, chosen when you order.

The largest screen. The iSteamX, at 7 inches.

A wireless control. The TempoFlex.

The simplest control. The TempoTouch: on, off and temperature.

Phone control. The SteamLinx module.

Weighing ThermaSol too? See our ThermaSol vs Mr. Steam comparison and our ThermaSol steam generator buying guide.

Frequently asked questions

Can Express Steam be added to a Mr. Steam generator later?

No. Mr. Steam's MS and MS Super manual says Express Steam is "only available factory installed," and each Express Steam version has its own model number. Choose it in the start-up speed step of our configurator.

Is AutoFlush required on a Mr. Steam generator?

No, it is an add-on that drains the generator automatically after each use. Both manuals call for opening the manual drain valve every 2 months, or more often in hard water areas, once the water has cooled, and both recommend AutoFlush in hard water areas.

What separates the MS, MS Super and MAX series?

MS covers 5 to 9 kW for adjusted volumes up to 257 cubic feet, MS Super 10 to 15 kW up to 482, and MAX 20 to 30 kW up to 964. A MAX also needs two or more steam heads and a 1 inch drain, and must never be hung on a wall or installed in a vanity.

How many steam heads does a Mr. Steam generator need?

A MAX needs two or more, spaced evenly, with piping that delivers an equal amount of steam to each. The MS and MS Super manual's instructions describe a single steam head and set no minimum.

Can the Mr. Steam control go outside the steam shower?

Yes. Outside, a remote temperature probe (part MSTS) must be installed inside the steam room. Inside, the control goes 4 to 5 feet above the floor near the seating area, on a vertical wall, away from the steam head.

How long is the Mr. Steam generator warranty?

Mr. Steam lists a limited lifetime warranty in the US and Canada: free in-home service, parts and labor for claims within 2 years of purchase, then parts for life. Controls and accessories carry a limited 2-year warranty.

Get pricing on a Mr. Steam generator

Send us your shower's dimensions, wall material, ceiling height and preferred control, and we will confirm the model and reply with current pricing.

Request pricing

Browse all Mr. Steam steam generators to compare the ten models.

ThermaSol, Mr. Steam and the product and feature names in this guide are trademarks of their respective owners.

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Mr. Steam Steam Generator Buying Guide: MS, MS Super and MAX Models Compared