Technical Note
How the system is sized, installed, serviced and guaranteed. A whole-home air purifier — technically a positive-pressure fresh air system — supplying filtered outdoor air through an installation assessed for the home. The plain answers, before you decide.
Sizing · filtration · civil work · thermal load · sealing and care · service · guarantees. October 2026 edition.
What’s inside
Always ask what’s inside. We’ll tell you ours.
| Part | What we use |
|---|---|
| Fan | EC fan — ~30 W, about ₹170 a month running 24×7 at ₹8/unit |
| Filter | H13 HEPA, Japanese media — particle filtration rated at the most-penetrating particle size |
| Body | High-grade sheet metal — outdoor-mounted; exposure and cover assessed on site |
| Engineering | Made in India — designed, assembled and tested in Gurugram |
| Proof | Live AQI on your phone — aqi0 monitor, available separately |
Best technology. Fair price.
System sizing and airflow
How one unit is sized to your home
Send us your carpet area and ceiling height and we return the figure for your home. The method: air changes per hour = effective airflow ÷ internal volume, where volume is carpet area × ceiling height.
| Carpet area | At 9 ft ceiling | At 10 ft ceiling |
|---|---|---|
| 1,000 sq ft | nominal air change ~31 min | ~34 min |
| 1,500 sq ft | ~46 min | ~51 min |
| 2,000 sq ft | ~60 min | ~68 min |
Theoretical vs practical. Those figures are computed for a sealed volume at 500 m³/h. A lived-in home is not sealed — the main door opens, cooking happens, balconies are used — so plan on roughly 50% of the theoretical rate: a 30-minute air change on paper behaves closer to an hour in practice. Treat that as a planning rule of thumb, not a measurement. Real rooms also mix unevenly, and duct resistance, filter loading, fan speed and how the rooms connect all move the result, so one nominal air change does not mean every part of the home has been cleared.
One unit is specified to 2,000 sq ft carpet. Beyond that, or across more than one floor, we specify two. Separate floors and rooms need suitable supply and exit paths; we’ll confirm the distribution plan with you.
Rated versus effective airflow
| Basis | Figure |
|---|---|
| Rated (free-air) | ~700 m³/h |
| Effective in service | ~500 m³/h |
| Fan | EC fan, variable speed |
All our sizing uses the effective figure. Filters impose static pressure, and the free-air rating is achieved only with no filters fitted. Free-air ratings are the norm in quotations, so it is worth checking on which basis any competing CFM figure is stated.
How filtered air reaches closed rooms without ducting into each one
The supply can create a small pressure difference that encourages air movement through available room connections and exit paths. Distribution depends on the layout, openings and exhaust operation; it is checked rather than assumed to be identical in every room.
Door undercuts and transfer paths matter. The design commonly allows around 10–12 mm of undercut on internal doors, but this is not a universal instruction to modify a door. Full threshold seals and fire-rated doors need appropriate assessment, and bedroom doors left open even an inch at night help. Rooms farther from the supply may respond differently. It is the external doors and windows that must close tight — see sealing the home below.
Bathrooms should remain on the extract side of the design. The installation must account for their exhaust and replacement air; positive pressure alone does not guarantee that air can never flow back towards occupied rooms.
Indoor benchmarks, windows and doors shut
| Measure | Target |
|---|---|
| PM2.5, fresh filters | under 10 µg/m³ |
| PM2.5, sustained across the filter cycle | under 15 µg/m³ |
| CO₂, continuous | under 1,000 ppm |
We hold below 15 µg/m³ across the whole filter cycle, not only after a filter change.
External windows and doors shut is the design condition. Bedroom CO₂ depends on occupancy and delivered outdoor air; a room HEPA purifier does not add outdoor air. An appropriate separate CO₂ instrument is needed to assess ventilation—the optional aqi0 monitor measures AQI and PM2.5.
Filtration and consumables
The filtration sequence
- Stage 1 — washable pre-filter. Dust, lint, insects. User-cleanable, pulls out like an AC filter.
- Stage 2 — H13 HEPA, Japanese media. The primary particulate stage. Three panels of 50 mm sit in series — 150 mm of media depth, roughly 6 m² of pleated area, about twenty times the face area. H13 classification specifies at least 99.95% integral efficiency at the most-penetrating particle size; that size is not a universal 0.3 µm cutoff.
- Optional — activated carbon. A carbon stage is available as an add-on at ₹2,200, refreshed about every six months and not covered by the care plan. It is worth being precise about what it does: carbon sits at the intake, so it adsorbs gases and odours in the air being drawn in — a neighbour’s cooking, traffic, a nearby exhaust outlet. It cannot remove VOCs generated inside the home, because the unit supplies air rather than recirculating it; those are reduced by dilution and by removing the source.
H13 is the specified grade. Each unit carries three panels at 362 × 276 × 50 mm, replaced on rotation—one panel per service visit. Rotation spreads replacements through the maintenance cycle; actual airflow still depends on loading, speed and the installation.
How often filters are cleaned or replaced
| Item | Interval |
|---|---|
| Pre-filter — vacuum or rinse, 2-minute DIY (how: below) | every 7–10 days |
| H13 HEPA — peak season (Oct–Feb) | every ~45 days |
| H13 HEPA — rest of the year | longer, set by pollution load |
The washable pre-filter reduces the coarse load reaching the H13 stage. Inspect and service the system for actual conditions; heavy pollution can affect loading. Let washed parts dry before refitting and do not wash the H13 panels.
Civil work, installation and aesthetics
What is needed on site
- One 10-inch circular opening — core-cut through the wall, a cut in window glass, or a cut in a wooden ply panel
- One 6A power point near the unit
- A wall bracket or a floor stand for the outdoor unit
These are the standard provisions. We also confirm structure, permission, mounting, service access, weather protection and the visible duct route with you. No HVAC integration is offered.
What is included in the installed price, and what is not
Included: the core cut, glass cut or ply cut; diffuser; ducting; electrical connection; wall bracket or floor stand; and weather sealing (silicone and closed-cell foam). Mounting and any vibration-control needs are assessed at the site.
Not included:
- Toughened glass. An ordinary pane we cut ourselves, covered by the price. Toughened glass cannot be cut after tempering and must be re-made at a factory. We arrange the re-cut and bill it as an extra, about ₹8,000–10,000 per pane. We raise this before quoting rather than after.
- A rain cowl or external cover. Where the mounting position is exposed we ask you to arrange one, and will advise on what is needed.
- A plug-point extension, if the nearest power point is far from the unit.
Where the outdoor intake goes, and how it is protected
Placement is confirmed with you before installation. The rules: away from kitchen exhausts, bathroom shafts, DG-set exhausts, basement parking vents, and the building’s own extract points. We do not mount on a kitchen-exhaust wall.
For rain, the louvre is downward-angled and the intake set above the local splash line.
On birds: the washable pre-filter is specified with this in mind — feathers, nesting debris and airborne matter are caught at the first stage, before the HEPA. Physical nesting on the body of the unit is a housekeeping matter at your end, as with any outdoor equipment on the façade.
This is the reason we confirm the intake position with you before quoting. Particle filtration does not establish removal of exhaust gases, so avoiding contaminated intake positions matters.
What you see indoors
There is no internal unit. The machine sits entirely outdoors — 14″ W × 17″ H × 20″ D. Indoors you see a single diffuser where the duct terminates. The visible duct route and finish are agreed for the property; the outdoor unit does not occupy indoor floor or shelf space.
Thermal impact, noise and power
Effect on room temperature, and on ACs and heaters
Yes, they will work harder. You are bringing outdoor air in continuously, so at 45°C or at 5°C there is a real added load. Any fresh-air system carries it.
Customer experience is more useful here than theory. Summer has not come up as a problem — hotter incoming air or AC load has not been raised with us. In winter, a heater can be fitted to the unit on request, so treated air arrives 5–6°C warmer — though we recommend room heaters, used as needed, as the better solution.
Beyond that it is a matter of setting. The fan is variable speed; most homes settle at a moderate setting year-round and lift it on peak-AQI days. Through temperature extremes you can run it lower, trading air-change interval against thermal load.
Noise
We do not publish a measured dB curve. At normal running it sounds like a ceiling fan on speed 2 — it runs in the background and you stop noticing it.
Two reasons it is quieter than expected. The fan is outdoors, so fan noise stays outside the building envelope. And an EC fan at a low duty point is genuinely quiet — noise becomes a consideration only well above the speeds a home runs at.
Power draw, and running on an inverter
| Measure | Figure |
|---|---|
| Normal operating draw | ~30 W |
| Running cost, continuous, at ₹8/unit | about ₹170 a month |
Maximum fan speed is seldom reached in practice. ~30 W is the figure that matters for sizing backup.
At roughly 30 W this is comparable to a single ceiling fan and runs on any standard domestic inverter with no meaningful effect on backup duration. Being an EC fan, consumption scales smoothly with speed rather than cycling on and off, so on backup you can simply run it lower.
Living with it: sealing, the pre-filter and your machine
Seal the home — it is what makes the system work
The system holds your home under gentle positive pressure, so clean air pushes out through the gaps instead of dirty air leaking in. That needs a properly sealed home: every external door and window closed and closing tight, latches locked, and any gap under or around an external door tucked in — no gaps whatsoever.
Check the home well, at least every night. Before bed, go round the balcony doors, the main door and every window: shut, latched, nothing left ajar. Night is when the home is closed longest and when bedroom air matters most.
- Where a door or window does not close tight, a door seal or draught strip closes the gap. We point out any gaps we see at the pre-installation visit; fitting them is at your end.
- Inside the home, live as usual. Internal doors keep their normal undercut — leave bedroom doors open even an inch at night, so fresh air reaches every bedroom.
- Open the external doors and windows only when you need to. The system is your ventilation.
- Run the chimney or exhaust while cooking, ideally with the kitchen door closed, so cooking air leaves the home rather than touring it.
Our performance commitment below holds only on a sealed home.
Cleaning the pre-filter — the one job that is yours
The washable pre-filter is the first thing outdoor air meets. It catches dust and lint before they reach the H13 panels. Once it clogs, less clean air reaches your rooms. Clean it every 7–10 days — two minutes, like an AC filter.
- Pull it out. No need to switch the machine off. At the air-intake end, pull the tab on top and the pre-filter slides straight up.
- Clean it. Vacuum it, or rinse it under a tap or a jet spray. Don’t just tap it out.
- Dry and refit. If you rinsed it, let it dry fully first. Slide it back in, tab on top, all the way down.
Most weeks a quick vacuum is enough. A repeating phone reminder every Sunday keeps you inside the 7–10 days.
Pre-filter only. Never wash the H13 HEPA panels. They stay inside the machine, and we replace them on care-plan visits.
Looking after your machine
- Keep it on, 24×7. Switch off only if you are away for four days or more.
- Leave the speed dial where we set it. The normal setting sits between 4 and 6, depending on the size of your home. Through temperature extremes you can run it lower.
- Keep the intake and the diffuser uncovered — no curtains, storage or plants against either — so the air can flow.
- Outdoors, the unit is housekeeping like any balcony equipment: keep the area around it clear, and tell us if birds start nesting on it.
Message us if something feels off: readings stay high with the windows shut, less air comes from the diffuser, a new noise or rattle, or the pre-filter is torn or won’t sit flat. On WhatsApp at +91 96676 72740 we typically reply within an hour, Mon–Sat 9am–6pm IST.
Care plan, warranty and service
What the annual care plan (AMC) covers
The annual care plan is optional and priced separately from the system; without it, H13 panels are ₹2,200 per panel (the unit holds three) and you can change them yourself in minutes. Filters are included, not labour-only: every scheduled visit covers filter replacement and a full machine clean. Unscheduled fault visits are also covered.
Cadence follows pollution load rather than the calendar: every ~45 days through the October–February peak, and at longer intervals through the rest of the year, set so indoor numbers stay in specification through the season that tests them. Each visit replaces one of the three H13 panels on rotation.
The care plan price does not rise on your first renewal. A customer who signs at ₹14,750 renews at ₹14,750; we do not reprice a plan because the system is already bought. A plan signed with the system carries 75 days on top — the first set of filters lasts about 50 days — so a 365-day plan runs 440 days, and two years of care taken upfront with the system run 805. Beyond that, renewals move in line with inflation rather than in steps.
The aqi0 air-quality monitor is available separately at ₹4,000, and the aqi0 Dial — a Wi-Fi remote control paired with the same app — at ₹7,500.
Warranty
| Component | Cover |
|---|---|
| Fan, while a care plan is active | up to 5 years |
| Fan, without a care plan | 1 year from installation |
| Fan rated life | 40,000 hours ≈ 4.5 years continuous |
| Speed controller / electronics | 3 years |
| Sheet-metal chassis | no warranty |
The fan carries one year from installation in all cases. Years two to five apply only if the care plan has never lapsed — renewed unbroken, the cover continues to a maximum of five years; if the plan lapses, cover reverts to that standard first year. Within warranty we repair the fan, or replace it with an equivalent unit — which may be new or refurbished. Rated life is a manufacturer’s figure, not the warranty period and not a prediction of the date a fan will fail.
The chassis is a powder-coated sheet-metal enclosure mounted outdoors. We do not warrant it against weathering over time.
Testing, our commitment and moving home
Measured before and after
Indoor PM2.5 is measured at installation — before the system is switched on, and again at commissioning. Both readings are recorded against your installation in our system.
A commissioning reading is one measurement on one day. Where an aqi0 monitor is installed, it gives continuous logged PM2.5 and AQI in your home, so performance can be reviewed across the whole winter rather than at a single point.
Our commitment, and what we cannot promise
What we commit to. In steady state — the home sealed as designed, filters current — the system holds PM2.5 under 10 µg/m³ with fresh filters and under 15 µg/m³ sustained across the filter cycle, and CO₂ under 1,000 ppm.
What we cannot promise. This is a positive-pressure system: it works by holding the home slightly above outdoor pressure, and that pressure is what keeps polluted air out. Where the envelope does not hold, the mechanism does not either:
- External windows or doors left open, or not closing tight — pressure is lost and outdoor air enters directly
- Windows or doors that leak badly — old or poorly sealed frames bleed pressure continuously
- An open kitchen without the exhaust running — cooking is itself a major indoor PM2.5 source
- Carpet area above 2,000 sq ft on a single unit
On everyday living. The main door opens, people come in, food is cooked. Each briefly mixes outdoor air into the room and produces short spikes. The system pulls the level back down and holds it, which is why the commitment is written against the sustained average rather than instantaneous readings.
Remedy. Where those conditions are met and the system does not perform, we rectify at our cost — filters, servicing, adjustment to the installation, or replacement of the unit if the fault is ours. Verification is against logged monitor readings where an aqi0 monitor is installed, and against our commissioning measurements otherwise.
If you move home
We shift the unit for you — removing it and reinstalling it at the new address. Two civil costs sit with you: restoring the old home (changing the glass back or filling the core cut), which you arrange at your end; and a nominal civil charge for the new opening at the new address, which we handle. Ask us for a shifting quote when the time comes — we set both out before the move.
Frequently asked questions
What size home does one unit cover?
Up to 2,000 sq ft carpet area. Beyond that, or across more than one floor, we specify two units. Separate floors and rooms need suitable supply and exit paths; we’ll confirm the distribution plan with you.
How does filtered air reach closed bedrooms without ducting into each room?
Air uses available transfer and exit paths, which must be assessed for the home. Door undercuts can support distribution; fully sealed or fire-rated doors need particular attention. The installation must also account for kitchen and bathroom exhaust.
Will my AC or heater work harder?
Yes. You are bringing outdoor air in continuously, so at 45°C or 5°C there is a real added load — any fresh-air system carries it. Summer has not come up as a problem with our customers. In winter, a heater can be fitted on request, so treated air arrives 5–6°C warmer, though we recommend room heaters, used as needed, as the better solution. Through the extremes, run the system at a lower speed.
How loud is it?
Like a ceiling fan on speed 2 — it runs in the background and you stop noticing it. The fan sits outdoors, so its noise stays outside the home. We do not publish a measured dB curve.
Does my home need to be sealed?
Yes — it is what makes the system work. Every external door and window must close tight, with any gap under or around an external door tucked in: no gaps whatsoever. Check the balcony doors, the main door and every window at least every night before bed. Internal doors keep their normal undercut; leave bedroom doors open even an inch at night.
How do I clean the pre-filter?
Every 7–10 days, without switching off: pull it out by the tab at the air-intake end, vacuum it or rinse it under a tap or a jet spray, and if rinsed let it dry fully before sliding it back in. Never wash the H13 HEPA panels.
What civil work is needed?
One 10-inch circular opening (core-cut through the wall, or a cut in window glass or a ply panel), one 6A power point near the unit, and a wall bracket or a floor stand. We’ll confirm mounting, service access and the visible duct route with you; the unit sits outdoors.
Is toughened glass included?
No. An ordinary pane we cut ourselves and it is covered by the price. Toughened glass cannot be cut after tempering and must be re-made at a factory; we arrange the re-cut and bill it as an extra, about ₹8,000–10,000 per pane. We raise this before quoting rather than after.
What does the warranty cover?
The fan is covered for as long as the machine stays on a care plan, up to five years; without a plan the cover is one year from installation. Within warranty we repair it or replace it with an equivalent unit, new or refurbished. The speed controller and electronics are covered for 3 years. The fan is rated for 40,000 hours, about 4.5 years of continuous running. The powder-coated sheet-metal chassis is mounted outdoors and is not warranted against weathering.
What happens if the system does not perform?
Where the home is sealed as designed and filters are current, we rectify at our cost — filters, servicing, adjustment to the installation, or replacement of the unit if the fault is ours. Verification is against logged monitor readings where an aqi0 monitor is installed, and against our commissioning measurements otherwise.
Can the system be moved if I change homes?
Yes. We shift the unit — removing it and reinstalling it at the new address. You cover the civil work to restore the old home (changing the glass back or filling the core cut), and a nominal civil charge covers the new opening. Ask us for a shifting quote when the time comes.
Further reading
H13 filter classification · Particle filtration and its limits · Bedroom ventilation measurement