02·STEAM

Steam Shower Generator

A deliberately oversized, commercial-grade steam generator stands on a shelf against the north wall of bedroom 3’s closet and supplies the master bath’s steam shower. This page covers the machine; running the shower itself is on the Master Bath page.

956 N Noble Loop · Showing Edition · Rev A · Aug 2026

At a glance

A steam generator boils a small reservoir of water electrically and pipes the steam to the master bathroom’s steam shower. It is a Mr. Steam MS400EC1, 9 kW at 240V single-phase — the largest single-tank model in Mr. Steam’s residential MS-series, rated for enclosures up to roughly 257 adjusted cubic feet, comfortably more than a single shower stall needs. Commercial-grade and deliberately oversized, in the same spirit as the water treatment, the network, and the electrical service.

Where: On a built shelf against the north wall of bedroom 3’s closet (the former office), at the end nearest the steam shower — which lies just beyond the closet’s northwest corner, so the steam run is short. That closet carries three separate systems on three different walls: this generator on the north wall, the network gear on a shelf dead centre, and the alarm panel on the south wall. You run the shower from a keypad in the bathroom (a Mr. Steam iTempoPlus — see Master Bath) and open this closet only for service.
Must know: It draws roughly 38 A at 240V single-phase on a dedicated circuit, needs a cold-water feed and a drain, and is not a plug-in appliance — repairs and replacement are an electrician-and-plumber job. Its flush system is set up and flushes correctly, it drains through a drain outlet, and the whole unit sits in a tray, so a drip or a drain fault has somewhere to go rather than reaching the floor. Its remote control unit is installed and working, and the remote stays with the house.
Status: Installed and operating. Trim package: Mr. Steam “Butler” (one round steamhead, polished chrome). Open item: which breaker feeds it — see Specs.

Location: upper floor — steam generator.

2Everyday use

You do not interact with this machine directly. Everyday steam-shower use — starting a session, setting temperature and duration, the aromatherapy or lighting features — is documented on the Master Bath page, where the in-shower keypad lives.

The only everyday-relevant fact about the generator itself: it needs its water supply valve open and its breaker on to work at all. If the in-shower controls are unresponsive or steam never starts, this page’s Troubleshooting section is where to look — the fix is usually in this closet, not the bathroom.

Where it is, and why that matters

The generator stands against the north wall of bedroom 3’s closet, at the end closest to the master shower — the shower is immediately beyond the closet’s northwest corner. That is the ideal placement: steam lines want to be short and to rise gently toward the heads, so a long run through the house (with condensation, heat loss, and a lag before steam actually arrives) is avoided entirely. It also means everything you might need to service is reachable from a closet you can walk into, not from inside a finished bathroom wall.

Three systems, three walls, one closet

Bedroom 3’s closet is the house’s small machine room. The steam generator is on the north wall. The network gear sits dead centre, up on a shelf, with the structured cabling coming out of the east wall. The alarm panel is on the south wall. Nothing in there competes for the same space, and each system has its own page in this manual.

Deliberately oversized — a theme in this house

The generator is a Mr. Steam MS400EC1, 9 kW at 240V, the largest single-tank model in Mr. Steam’s residential MS-series, rated for enclosures up to roughly 257 adjusted cubic feet — well above what this shower stall needs. That matches the rest of the house, where the pattern is repeatedly to specify a size or grade above the minimum: the water treatment system, the network, and the electrical service all follow the same logic. For a steam generator the practical upside is fast steam and a unit that never runs at its limit.

3Maintenance

The flush system does the routine work

Steam generators boil water repeatedly in a small tank, which concentrates minerals over time (scale) — exactly like a kettle. Left unaddressed, scale reduces steam output, triggers error codes, and shortens the heating element’s life. On this unit the flush system is set up and flushes correctly: the tank drains through the generator’s drain outlet rather than being drained by hand every couple of months, which is the routine Mr. Steam’s manual prescribes for a generator without one. The unit also sits in a tray plumbed to that drain, so a weep from a fitting or a slow drain has somewhere to go.

Softened water is the other half of the story

The generator is fed softened water from the house’s water treatment system, which is the single biggest reducer of scale formation in a steam generator. A working flush cycle plus softened feedwater is about as favourable a combination as this appliance can be given. The one thing that changes the picture is a stretch where the softener is in bypass or out of salt — worth remembering if steam output ever drops off.

Task	How often	Notes
Confirm the flush is still cycling	Twice a year	A quick look at the drain outlet and the tray after a session. A tray that is dry after every use, or standing water that never clears, are both worth a closer look.
Exercise the water-feed and drain valves	Annually	Open and close each fully so it does not seize. Do this at least 2–3 hours after a session, once the water has cooled.
Professional service	Annually	A technician inspects the heating element, the pressure and temperature safety devices, and the connections. Steam generators are a life-safety appliance (scald and overheat risk) as well as a comfort one.
Descale	On symptoms, not on a calendar	Weak steam, longer time to first steam, or a fault code referencing the element. With softened water and a working flush, this should be rare.
After a long idle period	Before returning to service	Exercise both valves and run a session with the drain observed before relying on it again.

Who to call: the installing plumber (Homola Plumbing, Inc. installed the steam package) or Mr. Steam’s authorized service network.
Water feed line: the dedicated cold-water line to the unit has an isolation valve — the thing to shut first if anything goes wrong here. Its exact position in the closet is to confirm.
Drain line: keep the drain path clear. A blocked drain is the one fault that turns the flush system from an asset into standing water in the tray.

4Troubleshooting

No steam at all: check the generator’s dedicated breaker in the main panel first — steam generators draw significant power and are the first thing to trip if a circuit is overloaded. Next, confirm the water supply valve to the unit (in the closet) is open. If both check out, look for an error or fault light on the generator itself or on the in-shower keypad.
Weak or intermittent steam: usually scale reducing heat-transfer efficiency, which points to a descale (see Maintenance) rather than a failed component. Check that the water softener has salt in it while you are at it.
Steam smells musty or “off”: check the drain — a restricted drain leaves water standing in the tank between sessions, which is exactly what the flush cycle exists to prevent.
Keypad in the bathroom is dead or unresponsive: confirm the generator has power (breaker) before assuming the keypad itself has failed. As with the Ecobee and the furnace, the visible control is often fine and the problem is upstream power.
Water in the tray, or water on the closet floor: the tray is doing its job — isolate the unit at its water shutoff valve, then find the source. See the Water leak runbook and the Plumbing page’s shutoff guidance.

Breaker and water valve first, always

Because the generator sits in a closet you rarely open, the fastest triage for almost any steam-shower complaint is: is the breaker on, and is the water valve open. Most “broken generator” calls turn out to be one of those two.

5Specs & identity

Identity
Type	Electric steam generator feeding the master bath’s steam shower
Grade / sizing	Commercial-grade and deliberately oversized — the MS400E is the largest single-tank model in Mr. Steam’s residential MS-series, rated for enclosures up to roughly 257 adjusted cubic feet, a step up from what a shower this size requires.
Make / model	Mr. Steam MS400EC1 (the “EC1” suffix denotes the electronic-control, single-phase package). Trim package: Mr. Steam “Butler” — one round steamhead, polished chrome. The in-shower keypad is a matching Mr. Steam iTempoPlus, covered on the Master Bath page.
Serial number	owner's edition
Install date	2017, during the original house build — delivered to the jobsite 2017-06-18 (Keller Supply, Vancouver → Homola Plumbing, Inc., the plumbing contractor of record).
Location	On a built shelf against the north wall of bedroom 3’s closet, at the end nearest the master shower, which lies just beyond the closet’s northwest corner.

Connections & electrical
Electrical circuit	Dedicated 240V single-phase circuit — nameplate rated 9 kW, ~38 A per Mr. Steam’s spec chart for the MS400E, on minimum 8 AWG wiring, which calls for a dedicated 40 A or 50 A breaker depending on how it was run. Which breaker in the main panel feeds it is still to identify — worth labelling once known.
Water feed	Dedicated cold-water line. The isolation valve’s exact position in the closet is to confirm.
Drain	The unit drains through its drain outlet, and stands in a tray — a leak or a drain fault is contained rather than reaching the floor
Flush system	Set up and flushing correctly — the tank drains on its own rather than needing the manual every-two-months drain routine a generator without a flush system requires
Remote control unit	Installed and working; the remote itself stays with the house
Control keypad	Mr. Steam iTempoPlus (round trim) in the master bathroom — see the Master Bath page for its operation and its aroma/chroma keys.

6Documents & links

Mr. Steam’s own documentation for this generator family.

Mr. Steam — Residential steam shower generators (MS90–MS400 line)
Official product page for the MS-series generator line, including the MS400E/MS400EC1 installed here.
Mr. Steam — Installation, Operation and Maintenance Manual (MS90E–MS400E, MSSUPER1E–3E)
The manual for this exact generator family — sizing chart (9 kW / 38 A / 257 ACF for the MS400E), electrical and water hookup, drain and flush procedures, and troubleshooting/status codes.
Mr. Steam — AutoFlush (auto-drain accessory)
Background on Mr. Steam’s auto-drain accessory and what an automatic flush cycle does for scale control.

Section 8Technical reference ExpandCollapse

The engineering layer — for a buyer's technician, or a curious owner.

How it works, briefly: a steam generator is essentially a small, sealed electric boiler — a heating element (or elements, on larger units) heats a water reservoir past boiling inside a pressure-rated tank, and the resulting steam is piped to the steam head inside the sealed shower enclosure. Because the enclosure must trap steam (unlike an ordinary shower), the stall needs a vapor-sealed door and a way to close off ventilation — that is the bathroom-side half of the system, documented on the Master Bath page, where the floor-to-ceiling front glass, the out-swinging solid glass door, and the gasketed louvred transom above it do that job.

Why oversizing matters here: a generator sized above the enclosure it serves buys three things day to day. Steam arrives faster, because a larger element brings the reservoir to boil sooner. The unit never runs flat out to hold temperature. And components last longer, because nothing is working at its rated ceiling. The costs are a larger electrical circuit (~38 A at 240V) and a slightly larger standby footprint. The usual third cost — a bigger reservoir whose scale burden grows with every litre boiled — is largely offset here by the combination of softened feedwater and a working flush cycle.

Safety systems: an over-temperature cutoff and an over-pressure relief device inside the tank (life-safety devices — never bypass or disable one if a fault code references it), a low-water cutoff to protect the heating element from running dry, and, at the shower head rather than the generator, a thermostatic anti-scald element limiting the output temperature a person can actually contact. GFCI protection on the circuit is standard practice for any water-adjacent electric appliance.

Open item: the dedicated breaker feeding this unit has not been identified in the main panel. Everything else on this page — make, model, serial, kW and voltage rating, trim package, water feed, drain and tray, flush system, remote control, and the installing contractor — is settled.