The short answer
- There is no single service interval. The right frequency depends on the manufacturer and model, the water, the hours of use, the type of use and the condition of the unit. The manual for your exact model governs.
- Harvia’s HGX, HGD and HGP generators show a service light 200 operating hours after the last service. In community and institutional use, Harvia asks for a thorough service at least twice a year.
- Automatic draining helps but isn’t maintenance. It flushes out concentrated water and loose sediment after use. Scale still forms, so descaling and servicing are still needed.
- Leave the power on. Switch off at the control panel, not at the isolator, so the drain cycle can finish.
- Descaling methods are brand-specific. Harvia uses citric acid; other makers use different products, and one forbids chemical descalers. Never borrow another brand’s method.
- Owners do a few defined jobs; the rest is for a qualified person. Harvia’s manuals list exactly which tasks a non-professional user may do.
This guide is about the generator. For water hardness and treatment, see our water quality guide and water filtration guide. For cleaning the room itself (tiles, grout, glass, benches and the floor), see steam room cleaning.
Why there is no universal service interval
A steam generator boils water. The water leaves as steam; the minerals stay behind as scale on the elements, the water-level sensor, the drain and the valves. How fast that happens depends on how much water is boiled and what is in it, so a calendar interval on its own tells you little.
| What changes the frequency | Why it matters | Source |
|---|---|---|
| Manufacturer and model | Each maker designs its own drain, level sensing and descaling routine, and sets its own interval and method. | Manufacturer manuals (Harvia and others) |
| Water hardness | Harder water deposits scale faster. One European maker shortens its descaling interval from every 500 operating hours in very soft water to every 30 hours in very hard water. | Manufacturer (anonymised) |
| Water treatment | A softener slows scale, and Harvia recommends one where the water is hard. Manufacturers say softening does not replace descaling. | Harvia; other manufacturers |
| Operating hours | Scale builds with hours of boiling, not months. Harvia’s service light counts operating hours. | Harvia HGX, HGD, HGP |
| Type of use | A generator running for hours a day in a hotel or gym reaches a home generator’s yearly hours in weeks. Harvia sets a twice-yearly minimum for community and institutional use; another maker asks for an extra service plan twice a year above about five hours a day. | Harvia; manufacturer (anonymised) |
| Automatic drain and rinse settings | Whether the drain runs after every session, and whether interval rinsing is switched on in long sessions, changes how much concentrated water stays in the tank. | Harvia HGX, HGD, HGP |
| Condition | Heavy scale found at one service, drain faults or recurring error codes mean the next service should come sooner. | General good practice |
A simple illustration of why hours matter: a home steam room used for an hour three times a week runs about 150 hours a year, so a 200-hour reminder comes round about every 16 months. A commercial room running ten hours a day reaches 200 hours in under three weeks. Same generator family, very different maintenance rhythm.
What Harvia publishes for HGX, HGD and HGP generators
Harvia’s current manuals for its HGX (home and light commercial), HGD and HGP (commercial) steam generators share the same maintenance framework. These are Harvia’s figures, for these models only:
| Item | Harvia’s guidance | Applies to |
|---|---|---|
| Service light | The indicator light starts blinking when 200 operating hours have passed since the previous service. The counter is reset after the service. | HGX, HGD, HGP |
| Community and institutional use | Must be serviced thoroughly at least twice a year: checking and cleaning the reservoir, the heating elements and the water-level sensor. | HGX, HGD, HGP |
| Sediment cup | Collects water impurities at the bottom of the unit. Empty it when it fills up, only once the generator has cooled completely (the HGX manual gives 24 hours from last use). | HGX, HGD, HGP |
| Water-level sensor | Remove lime deposits by wiping, or with very fine sandpaper if needed; check the silicone fittings for cracks; replace the sensor if needed. | HGD manual describes the steps; listed as a user task in all three |
| Descaling | Citric acid solution, 50–80 g per litre of water, left for an hour, then rinsed through as the manual sets out. Other descalers may be used following their packaging. | HGX, HGD, HGP |
| Who does what | Non-professional users may empty the sediment cup, clean the water-level sensor and descale. All other maintenance is for professional maintenance personnel. | HGX, HGD, HGP |
| Water quality | The guarantee depends on the water meeting Harvia’s water-quality table and on the unit being serviced as the manual describes. | HGX, HGD, HGP |
Harvia does not publish a fixed calendar interval for a home generator. The service light, the water at your property and the condition of the unit decide when it is due.
Older Harvia generators and other brands
The details above come from Harvia’s 2023 HGX XW, HGD XW and HGP XW manuals. Older Harvia models and editions, and other manufacturers’ generators, can differ. Match the manual to the type code on the generator’s rating plate.
Automatic drain and flush: what it does
Most modern generators drain and rinse themselves. Harvia’s HGX, HGD and HGP generators with the automatic discharge valve do three things:
- After switch-off, the generator rinses and empties the reservoir.
- Every fifth fill, it rinses the discharge pipe so deposits don’t settle there.
- During long sessions (optional), it empties and refills the reservoir at a set interval of 0.5, 1, 2, 3 or 4 hours. Harvia describes this for institutions where the generator runs for several hours at a time. Steam pauses for over five minutes while it happens.
Why it matters:
| What the drain removes | Why that helps |
|---|---|
| Concentrated water | During a session the water left in the tank becomes steadily more mineral-rich. Draining it away stops it depositing scale while the tank cools. |
| Loose sediment | Flakes of scale and other impurities are flushed out before they settle in the tank, the drain or the valves. |
| Stagnant water | An emptied tank doesn’t hold warm water between sessions, and the next session starts with fresh water. |
Why it does not make the generator maintenance-free
Draining removes the water, not the scale already stuck to the elements and the level sensor. Manufacturers are consistent on this: one notes that some scale stays in the tank even with automatic flushing, and Harvia’s manuals still call for descaling, sediment cup emptying, level sensor cleaning and scheduled servicing on models fitted with the automatic discharge valve. Treat any claim that automatic draining “removes all scale” with caution; it is not what the manuals say.
Why not to cut power at the isolator
The drain cycle runs after the generator is switched off at the control panel, and it needs power to do it. Harvia’s HGX manual says not to unplug the power while the tank empties after switch-off. If the generator is switched off at the isolator or circuit breaker after each session:
- the drain never runs, so the most concentrated water of the day sits in a hot tank and deposits scale;
- the discharge pipe isn’t rinsed, so deposits build up there;
- sediment stays in the reservoir until the next session.
Switch off at the control panel and leave the supply on. How the generator is isolated for servicing is designed by the licensed electrician.
Descaling
How often
Descaling frequency is set by each manufacturer for its own models and depends on:
- the manufacturer and model;
- the water hardness at the property;
- the operating hours;
- whether the water is softened or filtered, and how well that equipment is maintained;
- what the last service found.
Some makers tie descaling to hours and hardness, some prompt for it on the control, and one locks the generator if a descaling prompt is ignored. Harvia relates the need for descaling to water hardness, recommends a softener where the water is hard, and uses its 200-hour service light as the reminder. Your manual, your water and the generator’s condition decide the interval, not a rule of thumb.
Harvia’s method, for Harvia generators
Harvia’s HGX, HGD and HGP manuals describe descaling with a citric acid solution: 50–80 g of citric acid per litre of water, poured into the reservoir with the generator switched off at its main switch, left for one hour, then rinsed through using the generator’s rinse steps (which differ for manual and automatic discharge valves). Follow the manual for the exact sequence, because it includes running the generator before and after.
Other manufacturers differ
Descaling methods are not interchangeable between brands. Among the manuals we have reviewed:
- one European maker uses its own descaler, with the quantity set by the generator’s output, and asks for descaling at least twice a year even in private use;
- another European maker sets the interval by water hardness in operating hours;
- another prompts for descaling after a set number of operating hours and locks the unit if it is not done;
- one North American maker forbids chemical descalers on its commercial generators and relies on daily blowdown and mechanical cleaning instead.
Never transfer a descaling method from one brand to another, and never add descaler to a generator that is running. Use only what your generator’s manual describes.
What a preventative professional service may check
Manufacturers’ manuals, troubleshooting tables and commercial maintenance schedules point to the same group of components. What is actually checked depends on the model and the service person, but these are the items manufacturers list:
| Area | What may be checked | Why it matters | Where it comes from |
|---|---|---|---|
| Scale | Build-up in the reservoir and on internal parts; descaling as needed | Scale insulates the elements and blocks small passages | Harvia; other manufacturers |
| Reservoir (tank) | Checking and cleaning; sediment | Sediment and scale collect at the bottom | Harvia (twice-yearly service list) |
| Heating elements | Checking and cleaning; scale coating | Scaled elements run hotter, steam less and fail sooner | Harvia; one maker inspects an element for scale on larger units |
| Drain (discharge) valve | Operation, leaks, blockage | A stuck valve stops the flush or lets water run to drain continuously | Harvia error checks; another maker’s troubleshooting |
| Solenoid (inlet) valve and other valves | Filling correctly, no leaks | Fill faults are a common cause of water-level error codes | Harvia error checks |
| Water-level sensor or probes | Cleaning, fittings, replacement if needed | A fouled sensor misreads the level, causing fill faults, overfilling or error codes | Harvia; other manufacturers clean probes on a schedule in commercial use |
| Measurement cup | Cleaning | Harvia names it where the water level is not reached after switch-on | Harvia error checks |
| Controls | Error history, settings, operating hours, service counter reset | Settings such as interval rinsing and the service counter affect maintenance | Harvia |
| Electrical components | Wiring, connections and terminals, with the power isolated | Loose or corroded connections overheat | One commercial maker’s monthly and periodic schedule; licensed work |
| Overheat protector | Reset only after the cause is found | It trips for a reason | Harvia (professional reset only) |
| Steam outlet | Clear, clean, undamaged | A blocked outlet or pipe makes steam vent from the overpressure valve | Harvia |
| Steam pipe fall and insulation | Falls towards the room with no water pockets | Trapped condensate can spit hot water at the outlet | Harvia; other manufacturers |
| Leaks | Water and steam connections | Leaks damage the plant space and can be a sign of failing seals | One commercial maker’s schedule; general good practice |
| Water treatment | Softener or filter working, salt topped up, cartridges current | Treatment that has stopped working lets scale return quickly | Harvia recommends softening for hard water; general good practice |
This is a list of what manufacturers describe, not a fixed checklist or a description of any particular service visit. Ask whoever services your generator what their visit includes.
Owner tasks and technician tasks
Harvia draws the line clearly: its steam generator manuals list three maintenance tasks non-professional users may do, and leave everything else to professional maintenance personnel.
| Owner or operator (as the manual allows) | Licensed or authorised service person |
|---|---|
| Switch off at the control panel and leave the supply on so the drain can run | Any electrical work: supply, wiring, connections, internal fuses |
| Check the water supply valve is open | Opening the generator’s cover or dismantling the generator |
| Empty the sediment cup when full, only after the generator has fully cooled (Harvia HGX: 24 hours) | Resetting the overheat protector (Harvia: professional maintenance personnel only, after the cause is found) |
| Clean the water-level sensor, as the manual describes | Replacing elements, valves, sensors or circuit boards |
| Descale with the method in the manual | Investigating error codes not marked as user checks |
| Clean the steam outlet with mild soap solution (Harvia) | Investigating leaks, repeated tripping or drain faults |
| Note the service light, error codes and anything unusual | Plumbing alterations to supply, drain or steam pipe (licensed plumber) |
| Keep water treatment topped up as its supplier instructs | The thorough service Harvia requires at least twice a year in community and institutional use |
If you aren’t comfortable doing any of the owner tasks, leave them for the service visit. The unit and its water get very hot, and the tasks involve handling the generator’s water side.
Warning signs
Generators usually give warning before they stop. These are worth acting on:
| Sign | What it can point to | What to do |
|---|---|---|
| Less steam than usual | Scale on the elements, a fill fault, a failing element, service overdue | Arrange a service |
| Longer heat-up | Scale, element faults; one maker’s control reports an element fault when the water heats too slowly | Arrange a service |
| New or louder noises | Any change from how the generator normally sounds | Note when it happens and report it |
| Leaks at the generator, pipes or drain | Failing seals, valves or connections; steam from the overpressure valve can mean a blocked outlet or pipe (Harvia) | Switch off at the control panel and call a service person |
| Error codes | On Harvia generators, most codes relate to the water supply, the drain valve or the level sensor | Look up the code in your manual; check only what it marks as a user check |
| Visible scale at the outlet, in the sediment cup or in the reservoir | Hard water, missed descaling or a drain that isn’t running | Descale per the manual; review water treatment |
| Drain problems: water left in the tank, or water running to drain constantly | Discharge valve or level sensor faults; power cut at the isolator after use | Switch off at the control panel; service person |
| Odour from the reservoir or outlet | Harvia names fragrance flowing back from the steam pipe as one cause; water left standing in the tank is another | Service visit; make sure the drain runs after each use |
| Hot water spitting at the outlet | Water pockets in the steam pipe, scale or a fouled level sensor | Keep clear and arrange a service |
| Service light blinking (Harvia) | 200 operating hours since the last service | Book the service |
Our troubleshooting guide covers symptoms and Harvia’s steam generator error codes in more detail.
What owners should not do
- Don’t open the generator’s cover or dismantle the generator. The electrical and water-side internals are for a qualified person.
- Don’t bypass or disable a safety device, and don’t keep resetting a protector or breaker that trips. Repeated tripping needs a licensed or authorised service person to find the cause.
- Don’t use the isolator as an on/off switch. It stops the drain cycle.
- Don’t unfasten the sediment cup while the generator is in use or still hot. Harvia asks for complete cooling first.
- Don’t use another brand’s descaling method, and don’t add descaler while the generator is running.
- Don’t block the overpressure valve, and don’t put anything over or around the steam outlet.
- Don’t put fragrances or oils into the generator’s water unless the manufacturer’s system is designed for it; use only fragrance products made for your generator’s fragrance system.
- Don’t drain the generator into the steam room or alter the drain, supply or steam pipe. That is licensed plumbing work.
Compliance and licensed trades
Electrical work on steam generators and their controls is for a licensed electrician, following the manufacturer’s installation manual. Plumbing work on the water supply, drainage, water treatment and steam pipe is for a licensed plumber. This guide gives no wiring or electrical instructions. Commercial operators should confirm their maintenance, water-safety and record-keeping obligations with their work health and safety adviser and local council.
Service records
A simple record makes the next service quicker and supports a warranty claim. Harvia’s steam generator guarantees depend on the water requirements being met and the unit being serviced as the manual describes, and commercial guarantee periods are much shorter than for a home.
Good practice is to keep, with the generator’s manual:
- the model, type code and serial number from the rating plate, and the installation date and installer;
- each service: date, operating hours shown on the control, who attended, what was checked, cleaned or replaced;
- descaling and sediment cup emptying, with dates and what was found;
- error codes and faults: the code, what was happening, the cause and the fix;
- water treatment: test results, softener salt and settings, filter cartridge changes;
- any change to control settings, such as the rinse interval or service counter.
Why it matters: the record shows how fast scale is building at your property, which tells you whether the interval or the water treatment needs to change. Commercial operators can fold it into the maintenance log described in our commercial guide.
Getting a generator serviced
BSC Wellness works with a dedicated electrical contractor, an independent business and a Harvia-authorised service agent, who carries out our electrical servicing. Our service page explains how a service request works, or you can request a service directly.
Tell us what you have
When you get in touch about a steam generator, include the make, model and serial number from the rating plate, the operating hours shown on the control if you can find them, any error code, and a photo of the generator and its connections. It helps us work out the next step before anyone visits.