Installation & Planning
Updated August 2026 · For builders, plumbers, and contractors
The plumbing rules for a steam shower come down to five decisions made before the first fitting is threaded.
Get those five right and the rest of the install is detail work. Get any of them wrong and you inherit the problems steam specialists see most often: trapped condensate, spitting steam heads, inaccessible generators, and controls mounted where steam ruins them.
Below are the specs, and then a plumber who has spent years fixing other people's steam installs on what actually goes wrong.
In this post
Brass or copper only. PVC and PEX are not rated for steam temperatures and have no place anywhere in the steam line.
|
Water feed
3/8" NPT
|
Steam line
3/4" NPT
|
Drain
1/2" NPT
1" on MAX series
|
Put threaded unions at the connections. The plumber who services the system in ten years will either thank you or curse you depending on whether the line comes apart without cutting.
Pitch the steam line 3/4 inch per foot, sloped toward either the steam head or the generator. Steam traveling down the line constantly sheds condensate, and that water needs a continuous downhill path in one direction or the other. A line with a sag or a valley in it collects water at the low point, and the result is a steam head that spits and gurgles instead of delivering a steady flow.
Insulate longer runs. The less heat the line sheds on the way, the less condensate forms in the first place, and the faster steam reaches the room.
A steam generator needs two separate drain lines: one for the generator tank and one for the condensation pan. Combining them is one of the most common shortcuts found in failed installs, and it defeats the purpose of the pan.
While you are planning the drain runs, plan for maintenance. An AutoFlush accessory drains the tank automatically about two hours after each use, which reduces scale buildup and extends generator life. It only helps if the drain plumbing supports it, so decide on AutoFlush before the walls close, along with a drip pan sized to the generator family.
Between 15 and 25 PSI at the generator. Most homes run well above that, so plan on a pressure reducing valve in the feed line. High incoming pressure stresses the fill solenoid and shortens the life of components that would otherwise run quietly for years.
This is a five-minute decision during rough-in and an expensive one to retrofit, which is why it belongs on the spec sheet rather than the punch list.
Where plumbing meets layout
If the control is hard-wired, sleeve the wire in a conduit running from the generator to the control so it can be replaced without opening a wall. And never mount the control above the steam head or in its emission path, because direct steam makes it misread room temperature. The steam head itself mounts low on the wall, on the wall opposite the control, aimed away from where anyone sits or stands.
Phil Hotarek
Plumber · Lutz Plumbing
Lutz Plumbing has been family owned since 1929 and is an authorized MrSteam service provider. Phil has run roughly 15 steam installations, and he lives with one: his father put a steam shower in the family home more than 20 years ago, and Phil replaced it with a current system last year.
His preparation list is short and specific:
"I cannot tell you how many times I've seen plumbers make that mistake. But in all honesty, as long as you read the manual in detail while preparing for an installation, the project becomes a lot easier to execute and helps you minimize potential errors."
Phil Hotarek, Lutz Plumbing
He is also direct about who should be on the job. He works alongside contractors, builders, and electricians, and he considers steam experience a real qualification rather than a nice-to-have, because installers unfamiliar with steam and boiler systems make small errors or overlook critical items that cause the system to malfunction later.
On the documentation itself, his verdict is that MrSteam's manuals are clear and easy to understand, as long as you actually read them. The current residential manuals and specs are published by model, and Virtual Tech helps when you are troubleshooting alongside a customer.
Remodels are harder than new builds, and the reason is that you inherit someone else's decisions. On a new build, the plumber picks the generator location, routes the piping cleanly from the start, and makes sure everything can be serviced later. On a remodel, all of that has usually already been decided badly.
Phil's list of what he has found in existing installations is the best argument in this article for planning carefully:
"I have seen everything from cross-connected steam outlet and drain lines, to inaccessible generators, to controls that are installed right above the steam head, to wires chewed up by mice without the previous installer having planned for the ability to feed a new wire."
Phil Hotarek, Lutz Plumbing
Retrofits are also where a wireless control earns its price. Running new low-voltage communication wire through finished walls ranges from tedious to impossible, and MrSteam's TempoFlex connects to the generator by RF instead, from up to 60 feet from the wireless receiver. Construction materials affect that range, so test placement during the install rather than assuming it.
TempoFlex holds a six-month charge on its built-in rechargeable battery, or it can be hard-wired for continuous power while communication stays wireless. On replacement jobs, Phil reaches for a generator with the ButlerFlex package, which is built around that control.
Phil's advice to homeowners is mostly about decisions made before a plumber ever arrives:
He also recommends deciding on therapies early rather than later, since ChromaTherapy lighting, an AudioX sound system, and an AromaSteam pump are all easier to plan for during rough-in than to add afterward. His closing advice to plumbers new to steam is the same line he opened with: read the manual before installing.
The fastest way to get the generator size, control, and steam head combination right is to run the room through MrSteam's SmartSizing tool and build the system from there.
Size the system before rough-in
Run the room through the sizing tool, or talk with a local dealer before the walls close.
Steam Shower Sizing → Find a DealerCan I use PEX or PVC pipe for a steam shower?
No. Steam lines must be brass or copper. PEX and PVC are not rated for steam temperatures and will fail.
Which way should a steam line slope?
Downhill, continuously, at 3/4 inch per foot. The fall can run toward the steam head or back toward the generator, and either is fine. What fails is a line with a sag in the middle, because condensate collects at the low point and the head spits.
Does a steam generator need its own drain?
Yes, and so does the condensation pan. The two drains must be plumbed separately. Combining them defeats the purpose of the pan and is a frequent cause of failed installations.
Where should the steam generator be installed?
In an accessible, heated space within 60 feet of the shower, such as a closet, a vanity, a heated attic, or a basement. Never install it inside the steam room, outdoors, or anywhere the water supply could freeze.
Is the AirTempo control still available?
No. AirTempo has been discontinued. TempoFlex is the current wireless control, connecting by RF from up to 60 feet from the wireless receiver, which makes it the standard choice for retrofits where running new communication wire is impractical.
Can the control be mounted above the steam head?
No. Direct steam exposure makes the control misread room temperature, which is why it belongs on the wall opposite the steam head, out of the emission path.
What happens if the water pressure is too high?
Pressure above 25 PSI stresses the fill solenoid and other components. Install a pressure reducing valve to bring the feed down to 15 to 25 PSI.
Do I need a licensed plumber for a steam shower?
Yes. Every MrSteam install must follow the product-specific Installation, Operation & Maintenance Manual, and MrSteam directs installation to licensed contractors, architects, and designers. Current manuals are available in the residential guides and specs library.