PurAire FCU/2 and FCU/3 — Bipolar Ionisers for Fan Coil Units
Invisible, continuous odour treatment for hotel guest rooms and suites, fitted inside the fan coil unit
The PurAire SG-FCU/2 and SG-FCU/3 are Glass DBD bipolar ionisers designed for installation inside a fan coil unit or its supply-air section.
The FCU’s existing airflow distributes treated air through the guest room, so there is no separate room-side appliance and no additional fan for the guest to operate.
The SG-FCU/2 is the standard choice for rooms of approximately 50 to 70 m²; the SG-FCU/3 is intended for larger spaces of 100 m² and above, subject to FCU airflow, mounting space and room conditions.
The Hotel Room That Keeps Going Back on The Blocked List
Many hotels have guest rooms that are clean but still develop a recurring mildew-mouldy -musty, damp, cigar, cigarette odour, tobacco smoke smells, body or perfume odours or refurbishment-related odours.
Housekeeping cleans the room properly. Carpets, curtains and upholstery may be treated. The smell improves, then returns even when the air-conditioning runs.
A room held out of inventory that can’t be sold because of odour earns no room revenue while still carrying its normal operating costs. The FCU Series is designed for that recurring problem.
To put those rooms back into sellable inventory ASAP.
What is the PurAire FCU Series?
The SG-FCU/2 and SG-FCU/3 are Glass DBD bipolar ionisers designed to install inside a fan coil unit or its supply-air section, above the guest room ceiling.
The FCU’s own airflow distributes ions into the room. There is no separate fan, no ducting and nothing added to the guest space — the unit sits above the ceiling and the guest never knows it is there.
Because the ioniser is integrated into the FCU, there is no room-side unit for housekeeping to move, no separate fan in the guest space and no filter cartridge in the ioniser itself. The fixed installation remains in place after the initial odour problem improves, providing ongoing treatment and prevention whenever the unit is operating.
The FCU/2 uses two ionisation tubes and covers 50 to 70 m². The FCU/3 uses three and covers 100 m² and above.
There are no filters. The Glass DBD tubes are rated at approximately 17,000 operating hours and simply need an annual inspection and clean.
How Long Does an FCU Ioniser Take To Fix a Problem Room?
For deep-seated guest-room odours, think in terms of several days rather than hours.
An FCU-integrated system works progressively as room air recirculates through the fan coil. At the same time, odours absorbed into carpets, curtains, upholstery and other porous materials can continue to re-enter the room air. That is why a heavily affected room may improve gradually rather than all at once.
A Realistic Timeline...
In recent installations, odours typically begin to lift around the third or fourth day. By the end of the fifth day the room is usually where you want it. It’s sellable again, and Housekeeping and guests describe it as fresh and crisp.
How long depends on how bad the room was, how much the air conditioning runs, and how deeply the odour has soaked into the furnishings. A room that has been blocked for months may take a bit longer than one that has just started to smell. But – the odours will disappear!
Do Not Sell The Room On Day Two...
For a room that has been blocked and removed from inventory because of a persistent odour, we recommend allowing the full treatment period before putting that room back into service.
Very little change on day two does not necessarily indicate failure. Evaluate the room again around day five, and allow longer where the odour is unusually severe or the FCU operates for limited hours.
Be patient – the odour problem will resolve!
PurAire FCU Series
PurAire SG-FCU/2
Engineered specifically for seamless integration into medium-capacity Fan Coil Units (FCU) and central air-con ductwork, the FCU/2 utilizes dual high-output Glass DBD tubes to continuously clean and sanitize circulating air. It is ideal for commercial building managers, hotel operators, and office facilities teams looking to eliminate mould and mildew odours, stale odours from those “problem rooms” to put them back into sellable condition quietly, affordably and discretely.
Fits inside a medium-capacity fan coil unit and treats the room that the fan coil serves. The FCU/2 has adjustable ionisation levels and can be interlocked with the FCU fan or operated using an airflow switch, allowing bipolar ionisation to be distributed through the existing room air supply whenever the FCU operates.
For a whole building treated from the plant room instead, see the in-duct SG-BPI range.
- Best For: Hotel guest rooms and suites · Serviced apartments · Offices · Meeting rooms · Individual FCU zones
PurAire SG-FCU/3
Featuring a heavy-duty triple-tube configuration, the FCU/3 is built for high-airflow Fan Coil Units and larger-scale central air conditioning systems. It delivers greater ion density to tackle higher volumes of circulating air and tougher environmental pollutants. Perfect for larger hotel guest rooms and suites, VIP rooms, commercial complexes, high-traffic institutional spaces, and expansive office floors demanding continuous air purification and deodorisation.
Suited to larger fan coil units serving open-plan floors, function rooms and institutional spaces, where there is more air to treat than a two-tube unit can cover.
The FCU/3 also features an adjustable ionisation output control, and can be interlocked with the FCU fan or operated using an airflow switch, allowing bipolar ionisation to be distributed through the existing room air supply whenever the FCU operates.
- Best For: Larger Fan coil installations requiring a compact three-tube configuration · Hotels · Offices · Commercial occupied spaces
FCU/2 or FCU/3?
| PurAire SG-FCU/2 | PurAire SG-FCU/3 | |
|---|---|---|
| Coverage | 50 to 70 m² | 100 m² and above |
| Typical application | Standard guest rooms and suites | Large suites, presidential suites, apartments |
| Ionisation tubes | Two | Three |
| Technology | Glass DBD bipolar ionisation | Glass DBD bipolar ionisation |
| Certification | UL 2998 and UL 867 | UL 2998 and UL 867 |
| Filters | None | None |
| Tube service life | Approximately 17,000 hours | Approximately 17,000 hours |
| Maintenance | Annual inspection and tube clean | Annual inspection and tube clean |
| Warranty | 2 years unit / 1 year tubes | 2 years unit / 1 year tubes |
Room area is only the starting point. Final selection should also consider the FCU airflow, mounting space, room layout and operating hours.
Send us the FCU make and model, a clear photograph with the access panel open, and the room size. If airflow data are available, send those as well. We will confirm which model fits before anything is ordered.
What Odours Can the PurAire FCU Series Treat?
- Musty and mildew-related odours — the most common reason housekeepers, GM's and engineers call us
- Cigarette, cigar and tobacco odours in carpets, curtains and upholstery and floating in the air
- Vape odours
- Damp odours from the fan coil unit itself
- VOCs from recent refurbishment — new carpet, paint, adhesives, furniture
- Body and perspiration odours
- Food and cooking smells carried into the room
Mould and Mildew odours are the ones that bring most of our hotel enquiries. In Singapore’s humidity a fan coil unit stays damp, and the smell that develops there is carried into the room every time the air conditioning runs. Treating the air inside the FCU deals with it where it starts.
High humidity inside the rooms, and darkness and dampness, combined with the mould spores that are normally floating in the air and settling into the carpets and furnishings in Singapore, all contribute to that moldy, mildewy smell.
How are the SG-FCU/2 or SG-FCU/3 installed?
The unit installs inside the fan coil unit or its supply-air section, above the ceiling. Installation is quick and needs no modification to the room.
Operation can be interlocked to the FCU’s Fan using an airflow switch or an electrical interlock, so ionisation runs when the fan runs. That saves energy and avoids accumulating tube hours while the unit is off.
Once fitted there is nothing visible, nothing audible and nothing for housekeeping to operate. Send us the FCU make and model, or a photograph with the access panel open, and we will confirm the fit before scheduling.
Putting Blocked Rooms Back Into Inventory
This is the argument that matters to a a hotel’s GM and Owner.
A room held off the market because it smells earns nothing, and it goes on earning nothing indefinitely — most problem rooms have been problems for months. A unit fitted inside the FCU brings that room back within about five days and then keeps it that way.
And, or most properties the ROI is less than a weeks room revenue.
In Use Across Singapore...
In July and August 2026 alone, PurAire installed more than 100 SG-FCU/2 units in hotel and serviced-residence guest rooms and suites.
Both Housekeeping, Management and Engineeering feedback has repeatedly described treated rooms as noticeably fresher after the initial treatment period, including rooms that had previously been held back because of persistent odours with unsellable rooms being put back into sellable inventory.
Tell Us About the Room and the Fan Coil Unit
Send us the room size, FCU make and model, a clear photograph with the access panel open, how long the odour has been a problem and what type of smell you are dealing with.
We will recommend either the SG-FCU/2 or SG-FCU/3, confirm whether it fits, and explain the realistic treatment timeline before installation.
Free site evaluation across Singapore.
Whether you need five rooms done or five hundred.
PurAire Singapore, a division of ProMedUSA Pte Ltd
Office: +65 6836 9665
WhatsApp: +65 9456 8313
Frequently Asked Questions
Odours typically begin to lift around the third or fourth day, and the room is usually where you want it by the end of the fifth. Do not put the room back into inventory on day two — you may notice very little at that stage, and that is normal.
The FCU system provides ongoing treatment as room air recirculates through the fan coil. At the same time, odours absorbed into porous materials can continue to re-enter the room air, so a deep-seated problem can improve progressively over several days.
Singapore’s high humidity, room darkness, and the mould spores that are constantly floating in the air here in Singapore cause that mould and mildew to grow inside the fan coil unit itself, and the carpet and the soft furnishings.
The smell that develops in a damp FCU is carried into the room every time the air conditioning runs, which is why cleaning the room alone does not fix it.
Yes. The ions break down the compounds in tobacco odour held in curtains and carpets rather than covering them, which is what allows a former smoking room to be brought back into general inventory. Deep-seated smoke takes the full five days and occasionally longer.
The FCU/2 uses two ionisation tubes and covers 50 to 70 m². The FCU/3 uses three and covers 100 m² and above. Final selection should be based on the FCU airflow and mounting space as well as room size.
Inside the fan coil unit or its supply-air section, above the ceiling, so ions are distributed through the existing FCU airflow. Nothing is visible in the guest room.
Yes. Operation can be controlled with an airflow switch or electrical interlock so ionisation runs when the FCU fan runs.
Neither. The unit sits above the ceiling inside the FCU, has no fan of its own and nothing for guests to see or hear.
It is completely silent and invisible.
An annual inspection and a clean of the Glass DBD tubes. There are no filters to change and nothing to buy on a recurring schedule. The tubes are rated at approximately 17,000 operating hours.
Two years on the unit and one year on the tubes, the same as every PurAire product.
Singapore’s high humidity often leads to moisture being trapped within the FCU (Fan Coil) system, carpeting and soft furnishings. Traditional cleaning, even rigorous carpet cleaning can’t eliminate these odours.. The PurAire FCU series uses Bipolar Ionisation to destroy mould spores and organic odours at their source, rather than just covering them up like a fragrance.
Yes. The FCU/2 and FCU/3 are highly effective at neutralizing tobacco odours. The ions break down the chemical compounds of nicotine and tar trapped in curtains and carpets, allowing “smoking rooms” to be converted back to non-smoking inventory or quickly refreshed after a violation.
Most hotels report a noticeable difference in air “crispness” within the first hour. Complete remediation of deep-seated odours typically occurs within 12 to 24 hours, allowing you to put the room back into your sellable inventory almost immediately.
Not at all. Installation is simple and quick. The unit is installed inside the ceiling’s fan coil space. It is completely silent and invisible to the guest. Once installed, it provides 24/7 protection without any moving parts or guest-facing equipment.
The PurAire FCU series is designed for “set and forget” industrial use. There are no filters to change. We recommend a simple annual inspection and cleaning of the Glass DBD tubes, which are rated for approximately 17,000 hours of continuous operation (roughly 2 years).
SG-FCU/2 uses a two-tube ionisation configuration, while SG-FCU/3 uses three ionisation tubes. The models should not be selected simply by assuming that three tubes automatically means a larger airflow application.
They are designed for installation inside a fan coil unit or its supply-air section so bipolar ions can be distributed through the existing FCU airflow into the room or zone it serves.
Yes. Depending on the installation, operation can be controlled using an airflow switch or electrical interlock so ionisation operates when the FCU fan is running.
Published PurAire technical information rates the Glass DBD ionisation tubes at approximately 17,000 operating hours. Actual replacement timing depends on operating hours and maintenance conditions.
Selection should be based on FCU airflow, available mounting space, room requirements and the specific installation configuration. Because current published airflow and coverage information does not support a simple “FCU/3 is larger” rule, application sizing should be confirmed before specifying a model.