Oct 26, 2026

Ceiling Suspended vs Floor Mounted AHU: How to Choose the Right One

A ceiling suspended AHU hangs from the slab above the false ceiling, so it suits buildings with little plant room space. A floor mounted AHU stands on a plinth in a plant room and suits large airflows and heavy-duty use. Choose by space, airflow, filtration and servicing access.Most AHU quotations begin with a capacity figure, but the first real decision is simpler: where will the unit sit? Put it in the wrong place and you pay for it every year, in noise complaints, awkward filter changes and ducting that runs further than it should.This guide compares the two layouts we are asked about most, the ceiling suspended AHU and the floor mounted AHU, and gives you a short set of questions to settle the choice for your own building.What Each Type IsAn air handling unit does the same job in both layouts. A fan moves air through filters and a cooling coil, sometimes a heating coil or humidity section, and sends it into ducts. What changes is the housing and how it is supported.A ceiling suspended AHU is a compact unit hung from the slab on rods or brackets, usually inside the false ceiling void. A floor mounted AHU is a larger modular unit that sits on a base frame or plinth, normally in a dedicated plant room, and can be built from several sections joined in a row.When a Ceiling Suspended AHU Makes SenseThe main reason to choose a suspended unit is space. If the building has no spare plant room, or the plant room was given to something else during design, hanging the AHU above the ceiling frees that floor area for rent or use.It fits well in offices, hotels, malls, hospitals and other commercial buildings where each floor or zone has its own unit. Airtree's Ceiling Suspended AHU covers 700 to 12,000 CFM, can be supplied with or without treated fresh air, and can include double-skin panels and access doors for maintenance.The trade-offs are real, though. Capacity tops out lower than a floor mounted unit, the structure above must carry the weight, and servicing happens overhead. Filter and coil access needs a proper service panel in the ceiling and enough clearance to work.When a Floor Mounted AHU Makes SenseA floor mounted unit is the workhorse for large airflows and demanding air quality. Because it stands on the ground, it can be longer, taller and heavier, with room for extra sections such as multi-stage filters, a heat recovery section, a humidity section and large coils.That is why it shows up in pharma plants, hospitals, laboratories, airports and clean rooms. Airtree's Floor Mounted AHU is built for high air volumes and critical applications, and can be configured for return air, fresh air or treated fresh air.The cost is floor area. You need a plant room, a plinth, clear space around the unit for coil pull-out and filter access, and a duct route into the building. In return, servicing is easier, because technicians work at floor level with the unit's full length in front of them.Ceiling Suspended vs Floor Mounted AHU: Side by SideFactorCeiling suspendedFloor mountedInstallationHung from the slab, above the false ceilingOn a plinth in a plant roomFloor areaNone usedNeeds a plant roomAir volumeSmall to mid-size (Airtree: 700 to 12,000 CFM)Mid-size to very largeSections and filtrationPossible, but limited by unit sizeMore sections, more room for fine filter stagesServicingOverhead, through access panelsAt floor level, full accessNoiseClose to occupied rooms, needs careKept away in the plant roomTypical useOffices, hotels, malls, floor-wise zonesHospitals, pharma, labs, airports, clean roomsSix Questions That Settle the ChoiceHow much air do you need? Work out the airflow for the zone first. Small and mid-size zones suit a suspended unit. Very large halls or whole-wing duties lean toward floor mounted.Do you have a plant room? If you do not, and cannot create one, the decision is already made.How strict is the air quality brief? Clean rooms, operation theatres and pharma areas need several filter stages and tight humidity control, which is easier to build into a longer floor mounted unit.Can the ceiling carry it? A suspended unit puts its full weight on the slab. Ask your structural engineer to confirm the hangers and load before you order.How loud can it be? A unit above a meeting room or hotel corridor sits close to people. Check the noise data and use vibration isolators. A plant room keeps that sound away from occupants.Who will service it, and how? Count the units. Twenty suspended AHUs mean twenty overhead service points, while two floor mounted units mean two. Plan the access panels now.Many buildings use both: floor mounted units in the plant room for large halls and critical zones, suspended units on upper floors where space is tight. A treated fresh air unit can then handle ventilation for either, which matters when you design to ASHRAE 62.1 rates.Common Mistakes to AvoidSizing by tonnage per square foot alone, instead of a proper load calculation.Choosing a suspended unit and forgetting the service clearance around it.Ignoring noise when the unit sits above an occupied room.Placing filters and coils where nobody can reach them, so they never get cleaned. Our guide on cleaning an AHU cooling coil shows what regular access saves you.Treating fresh air as an afterthought. For wider system choices, see our guide to choosing the right HVAC system.Where Airtree Fits InAirtree makes both layouts in Greater Noida, along with Vertical AHUs, Cooling coils and treated fresh air units, so one team can specify the whole air path. If you are unsure which suits your project, share your layout, airflow and air quality needs and the engineers will recommend a configuration.Browse the air handling unit range, see the full products catalogue, or get a quote. If you are weighing AHUs against room-level units, our comparison of AHU vs FCU explains the difference.Frequently Asked QuestionsWhat is the main difference between a ceiling suspended and a floor mounted AHU? A ceiling suspended AHU hangs above the false ceiling and saves floor space. A floor mounted AHU stands in a plant room and handles larger airflows and more sections.Which AHU is better for hospitals? Both are used. Critical zones with strict filtration and humidity control usually get floor mounted units, while lighter-duty areas can use ceiling suspended ones.What airflow does a ceiling suspended AHU cover? Airtree's Ceiling Suspended AHU covers 700 to 12,000 CFM, with or without treated fresh air.Does a ceiling suspended AHU need a plant room? No. It goes above the false ceiling, but it needs structural support, service access and a drain route for condensate.Can one building use both types? Yes. Many buildings pair floor mounted units for large or critical zones with suspended units where space is limited.Keep reading: browse the Airtree blog or the Knowledge Hub for more on air handling and ventilation.

Oct 19, 2026

Winter Smog in Delhi NCR: How Fresh Air Units and Filtration Improve Indoor Air Quality

A fresh air unit is a ventilation system that draws outdoor air through filters, treats it and supplies it to a building at a controlled rate while stale air is exhausted. In smog season, it keeps PM2.5 out and CO2 down without opening windows.Around the last week of October, Delhi NCR changes. The sun looks pale by late afternoon, the air smells faintly of smoke, and the AQI app becomes the first thing people check in the morning. Most offices and households respond the same way: shut the windows, switch on a purifier, and wait for the wind to turn.That helps, but it is only half a plan. A sealed room with no fresh air brings its own problems, from stuffy meeting rooms to heavy-headed afternoons. This guide explains why winter smog in Delhi NCR gets indoors, what actually cleans the air you breathe, and how fresh air units and filtration work together.Why Delhi NCR Smog Peaks in WinterThe region does not suddenly produce more pollution in November. The weather just stops clearing it. Cold nights and weak winds create a temperature inversion, a layer of warm air sitting over cooler air near the ground, which works like a lid. Vehicle exhaust, construction dust, industrial emissions, waste burning and smoke from crop residue fires in neighbouring states all collect underneath it.The pollutant to watch is PM2.5: particles under 2.5 microns, roughly thirty times thinner than a human hair. They slip past the nose and throat and settle deep in the lungs. India's national standard allows a 24-hour average of 60 µg/m³ for PM2.5, while the World Health Organization recommends a much stricter 15 µg/m³. On bad days, NCR readings run well past both.Why Your Indoor Air Is Not as Clean as You ThinkIt is easy to assume indoor air is safer. During smog season that is only partly true. Outdoor air leaks in through door frames, window tracks, balcony sliders and the gaps around AC sleeves and pipe cut-outs. Indoor PM2.5 usually follows the outdoor reading with a delay of a few hours.Then there is what we add ourselves: cooking fumes, incense, cleaning sprays, dust from carpets and the carbon dioxide every person breathes out. In a closed office or bedroom, CO2 builds up quickly. Many ventilation guidelines treat a sustained level above roughly 1,000 ppm as a sign of under-ventilation. People feel it as a heavy head and poor focus, then blame the smog.So the goal has two parts: keep polluted air out, and keep fresh air coming in.What a Fresh Air Unit DoesA fresh air unit draws outdoor air through filters, treats it and supplies it to the building at a controlled rate, while stale air leaves through a separate exhaust path. In larger buildings this job usually goes to a treated fresh air unit, which cools, heats, dehumidifies and filters 100% outside air before it reaches occupied rooms. Airtree's Treated Fresh Air Unit is built for exactly this.Three things change once one is running:Pollutants get diluted. Fresh, filtered air replaces air loaded with CO2, moisture, odours and cooking particles.The building stays slightly pressurised. When a little more air is supplied than leaves, air pushes outward through gaps instead of pulling unfiltered smog in.Windows stay shut. You get ventilation without inviting the smog inside.Many setups also add a heat recovery unit, which passes heat between outgoing and incoming air. That cuts the load on your cooling and heating.Filtration: The Part That Does the Real WorkA fresh air unit is only as good as the filters inside it. Good systems clean air in stages.Pre-filter. Catches coarse dust, hair, insects and pollen, and protects everything behind it.Fine filter (F7 to F9 class). Captures most PM10 and a useful share of PM2.5.HEPA filter (H13 or higher). Removes at least 99.95% of particles at the most penetrating size, which is why it is the usual benchmark for smog-grade cleaning.Activated carbon layer. Adsorbs smoke smell and some gases, including VOCs.Two practical points. First, filters clog faster in smog months, so follow the replacement schedule and inspect them more often between October and February. A clean cooling coil matters as well, and our guide on cleaning an AHU cooling coil without damaging the fins shows how.Second, a filter only works when air is forced through it. Poorly sealed housings let air slip around the media, so installation quality counts as much as the filter grade. The casing matters too. Double-skin panels, like those on Airtree's Double Skin Fresh Air Unit, add insulation and keep noise down.Fresh Air Unit vs Air Purifier: Which Do You Need?The two are often treated as rivals, but they solve different problems.A standalone air purifier recirculates and cleans the air already in the room. It is portable and good at removing particles. It cannot lower CO2 or bring in outside air.A fresh air unit ventilates the whole space and filters what enters. It is a fixed installation, but it fixes the stuffiness a closed-window winter creates.For most NCR buildings, a sensible plan is a fresh air unit for baseline ventilation and filtration, with portable purifiers as a boost in rooms that need it, such as a clinic waiting area or a nursery. If you are weighing larger systems, our comparison of AHU vs FCU explains where each one fits.A Smog-Season Checklist for Any BuildingThese habits help whether or not you have a system installed:Check the AQI before opening a window, and air the building out when readings dip, usually mid-afternoon.Seal gaps with weatherstripping and door sweeps.Run the kitchen exhaust while cooking and skip incense in closed rooms.Keep a CO2 and PM2.5 monitor where people spend long hours.Service filters before the season starts, not halfway through it.Where Airtree Fits InAirtree is an HVAC and ventilation manufacturer based in Greater Noida, supplying projects across Delhi, Noida, Gurugram, Ghaziabad and Faridabad. The range covers treated fresh air units, air handling units, heat recovery units and cooling coils, all made in-house.For offices, hospitals, malls, hotels and premium residential buildings, the team can study your floor plan, occupancy and fresh air requirement, then specify unit size and filter stages to match. Planning now, before the heaviest weeks in November, leaves time to size the system and schedule installation properly. You can browse the full products catalogue, look at the air ventilation and cooling systems, or get a quote.Frequently Asked QuestionsDoes winter smog affect indoor air quality?Yes. Outdoor PM2.5 enters through gaps in doors and windows, and indoor levels usually rise a few hours after outdoor levels do.Can a fresh air unit remove PM2.5? Yes, when it has fine and HEPA-grade filters. Incoming air passes through them before it reaches the rooms.Is a fresh air unit better than an air purifier?They do different jobs. Purifiers clean recirculated air. Fresh air units bring in filtered outdoor air and expel stale air, which also controls CO2. Many buildings use both.How often should filters be changed in Delhi NCR? It depends on the filter type and usage, but smog season shortens filter life. Follow the maker's schedule and inspect filters more often between October and February.Is it safe to keep windows closed all winter?Closed windows keep smog out, but without mechanical ventilation, CO2 and moisture build up. A fresh air unit solves that.Keep reading: browse the Airtree blog or the Knowledge Hub for more on ventilation and indoor air.

Oct 14, 2026

What Is an Air Washer? Working Principle and Uses in Factories

An Air washer is an air treatment unit that cools, cleans and humidifies air by passing it through water or a wet cooling pad. Factories use it to bring down shop-floor temperature, control dust and keep humidity at a workable level, usually at a much lower running cost than a full refrigeration-based system.If you manage a plant in a hot, dry region, you already know the problem. Machines run hot, workers slow down, and dust settles on everything. An air washer is one of the simpler fixes. This guide explains what it is, how it works, and where it fits in industrial settings. It also covers what to look at before you buy one.What is an Air Washer?An Air Washer is a ventilation and cooling system that treats fresh outside air before it enters a building. Hot, dry air goes in. Cooler, cleaner and slightly more humid air comes out.The cooling comes from evaporation. When water evaporates, it takes heat from the surrounding air. This is the same reason a wet cloth feels cold in a breeze. An air washer does this in a controlled way, with a fan to move the air and a pad or spray section to hold the water.Some people call it an evaporative cooler or an air scrubber. The names overlap, but the core job is the same: use water to treat air.How does an Air Washer Work?The working principle is easy to follow once you see the sequence.Air intake. A fan pulls outside air into the unit through a filter, which catches the larger particles first.Contact with water. The air passes through a wetted cooling pad or a water spray section. Water evaporates into the air stream and pulls heat out of it.Dust and odour removal. While the air is in contact with water, dust particles stick to the wet surface and get washed away. Some odours and soluble gases are absorbed too.Mist elimination. Mist eliminators stop water droplets from travelling into the supply duct, so the air leaving the unit is cool but not dripping.Supply. The conditioned air moves through ducts or directly into the space.The temperature drop depends on how dry the incoming air is. The drier the air, the more cooling you get. This is why air washers do especially well in hot, arid climates, and why they struggle during humid monsoon weeks. Hybrid designs exist to deal with that, and we cover them below.Types of Air WashersSingle stage. Air goes through one wet section. It is the simplest and cheapest option, suited to basic cooling and dust control.Double stage. Air is first pre-cooled through a heat exchanger with no water contact, then it passes through the wet pad. Because the air arrives already cooler, the final temperature is lower and humidity does not climb as much. Airtree’s Double Stage Air Washer Unit works this way, with mist eliminators at the end to prevent water carryover.Hybrid (three stage). This type adds DX cooling to the mix. In dry weather, the air uses the evaporative pad. When humidity is high, the pad is bypassed and the air goes through a DX coil, which cools and dehumidifies at the same time. The switching is automatic. If your plant faces both dry summers and sticky monsoons, the Hybrid Air Washer handles both without two separate systems.Double skin construction. Airtree also builds Double Skin Air Washers with insulated panels. They are used for industrial exhaust, kitchen fumes and process emissions as well as comfort cooling.Where factories use air washers ?Air washers show up across many industrial settings. These are the most common ones.Textile and spinning mills. Yarn breaks more often when the air is too dry. Controlled humidity keeps fibres workable and cuts static.Automobile and engineering plants. Large halls with welding and machining get very hot. Air washers lower the floor temperature without the power bill of full air conditioning.Printing and packaging. Paper behaves better at stable humidity, which reduces curling and registration problems.Electronics and assembly. Dust control matters here, and so does moderate humidity to limit static discharge.Food processing and cold-chain support areas. Clean, temperature-managed air helps with hygiene in production halls.Foundries, kitchens and heavy-heat zones. Where heat and fumes build up, washing the air helps with both.In many of these plants, air washers work alongside other equipment. Exhaust fans such as tube axial fans push stale air out, and the air washer supplies fresh conditioned air in. Where fumes are a concern, a wet scrubber cleans the exhaust stream before it leaves the building.Benefits worth knowingLower energy use compared with compressor-based coolingFresh air supply, not recirculated airDust and some odour reduction at the same time as coolingBetter humidity for processes that need itSimple maintenance on most designsLimits you should plan forAir washers are not a universal answer. In very humid weather, evaporative cooling loses strength. They also need a clean water supply, regular pad cleaning and attention to water quality. If your process needs very tight humidity or temperature control, you may need an AHU with cooling coils or a dehumidifier in the mix.How to choose the right Air Washer Unit ?Before you pick a model, work through these questions:What is the typical outdoor humidity at your site across the year?How large is the space, and how many air changes per hour do you need?Does the process need strict humidity limits?How much heat and dust do machines add?Is water supply reliable and of reasonable quality?An honest answer to these usually points to single stage, double stage or hybrid. If you are unsure, a site visit and a heat load calculation save money later. You can see the full range on the Airtree products page, or talk to the team through the contact page.About AirtreeAirtree is an Indian HVAC and ventilation company, a unit of We4U Maintenance Pvt Ltd, based in Greater Noida. Its range covers air handling units, cooling coils, dehumidifiers, air washers, fans and pollution control equipment. For more reading, visit the Airtree blog and the Knowledge Hub.Frequently Asked QuestionsWhat is an air washer in simple words? It is a machine that cools and cleans air using water. Air passes over a wet pad, heat leaves the air as the water evaporates, and dust gets trapped in the water.How is an air washer different from an air conditioner?An air conditioner uses a refrigerant and compressor and usually recirculates indoor air. An air washer uses evaporation and supplies fresh outside air, so it generally costs less to run.Does an air washer work in humid weather? Pure evaporative designs lose performance when humidity is high. A hybrid air washer switches to DX cooling in those conditions, so it keeps working.Which factories benefit most from air washers? Textile mills, engineering and automobile plants, printing units, electronics assembly and food processing halls see the most benefit.How often does an air washer need maintenance? Check water quality and pads regularly, and clean the pads and tank on a schedule that suits your dust and water conditions. Your supplier can set a routine for your site.

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