An air handling unit or a paint-booth supply fan almost never runs at its design duty. It spends its life throttled — and a damper does not save you a rupee, it just burns the energy somewhere else. An EC fan solves that at the motor: a brushless permanent-magnet machine with the speed controller built in, stepless from a 0–10 V or PWM signal, with no drive panel, no belt and no pulley alignment. We engineer, supply, install and service them from Ahilyanagar.
Three things change. Everything else about selecting and installing the fan stays exactly as you already know it.
An induction motor has to induce the rotor field, and burns real power doing it. A permanent-magnet rotor does not. There is no slip and no rotor excitation loss — which is why the efficiency gap widens as you throttle back rather than closing.
No separate variable-frequency panel to buy, wire, find space for, cool or maintain. No long motor cable. Speed comes from a simple 0–10 V or PWM signal, stepless across the range. Speed feedback and a fault indication are available on some models — we confirm the control interface against the specific model before it goes on a quotation.
It is a backward-curved centrifugal impeller — the same aerodynamic family we have built for years, selected on the same two numbers, off the same P–Q curve. The motor changed, not the fan. If you can size one of our fans, you can size this.
Between colour changes, flash-off, shift patterns and seasonal load, a booth or AHU fan rarely sits at design flow. There are three ways to give it less air, and they cost wildly different amounts.
Power barely falls. You are throttling against the fan and paying for the pressure you just destroyed. Still the most common arrangement on older plant.
Better. Power comes down somewhat. Common on larger legacy units, and a real improvement on a damper — but it is still a mechanical dodge.
Flow falls with speed, pressure with the square, and power with the cube — run at 80% speed and shaft power drops to roughly half. An EC fan does this natively, with nothing bolted on.
A belt drive quietly loses a few per cent on its own, then stretches, slips, needs tensioning, and eventually snaps at the worst possible moment. Direct drive removes the belt, the pulleys, the alignment, the guard, the spares and the maintenance visit.
In a paint booth or a cleanroom there is a second reason that matters more than the maintenance: belt dust is a product-quality problem, not just a housekeeping one. Taking the belt out of the air path upstream of a surface that has to be flawless is worth something on its own.
Put four or six small EC fans in the plenum instead of one large one and you get something the original never had: when one stops, the rest keep running. In a paint line the expensive event is not the failed fan — it is the stopped booth. The array also fits through a standard doorway, which is often the only reason a retrofit is possible at all.
A documented retrofit by the manufacturer: one belt-driven AC centrifugal fan replaced with five EC fans in a wall. We are quoting their figures, and we are quoting them in full — including the part most people leave out.
One belt-driven AC centrifugal fan moving 26,600 m³/h and drawing 18.8 kW. No intelligent control, and an installation the manufacturer describes as complicated.
Five EC high-static-pressure fans in a wall, moving 39,600 m³/h for 11 kW. Stepless control, straightforward installation, and redundancy built into the arrangement.
The manufacturer headlines this as a 41.5% energy saving. That is the fall in absolute power — but the airflow rose 49% at the same time, so it is not a like-for-like comparison and we are not going to present it as one. The honest number is the better one: measured as energy per cubic metre of air actually moved, the retrofit cut consumption by about 61%, from 0.707 to 0.278 kW per 1,000 m³/h.
The manufacturer also reports an annual electricity saving on a basis of 8,760 running hours at CNY 1/kWh. We will not translate that into a rupee figure for you, because a saving computed on someone else's tariff tells you nothing. Give us your rate and your running hours and we will do the arithmetic with you, on your numbers.
All three are backward-curved centrifugal fans with the controller on board. They differ in what they are tuned for: pressure, general air handling, or quiet.
The paint-booth and high-resistance line. Sheet-aluminium impellers, three-phase, built for systems with real pressure drop — deep filter banks, long duct runs, loaded pre-filters. This is the range behind the retrofit above.
The AHU workhorses, and the set we hold as samples. Sheet aluminium, IP54, Class F, G4.0 balance, L10 40,000 h minimum, 0–10 V or PWM in. Covers roughly 3,055 to 23,515 m³/h free air.
Purpose-built for filter and fan units in pharma, electronics and food. Single-phase 220 V, plastic or aluminium impellers, including two ultra-thin frames for tight ceiling voids. The quietest frames run at 51–54 dB(A).
| Impeller | Supply | Max airflow | Max static | Input power | Sound pressure |
|---|---|---|---|---|---|
| Ø250 | 220 V 1-ph | 3,055 m³/h | 1,096 Pa | 750 W | 87 dB(A) |
| Ø355 | 380 V 3-ph | 7,440 m³/h | 1,488 Pa | 2,300 W | 91 dB(A) |
| Ø450 | 380 V 3-ph | 15,202 m³/h | 1,832 Pa | 5,400 W | 95 dB(A) |
| Ø560 | 380 V 3-ph | 20,908 m³/h | 1,400 Pa | 5,600 W | 96 dB(A) |
| Ø630 | 380 V 3-ph | 23,515 m³/h | 1,504 Pa | 6,900 W | 87 dB(A) |
A fan never delivers its maximum airflow and its maximum static pressure at once — they are different points on the same curve, and the highest static a model reaches occurs well below full flow. Your duty point sits somewhere on the curve between them, and that is what we select against. These five are tuned to a premium paint-booth specification; we re-select to your actual duty before quoting. Sound pressure is the catalogue maximum, not the level at your operating point.
Send us the numbers and we will come back with a selection and the payback worked on your own figures.
We would rather lose the enquiry than sell you a fan that fails in your duty. This is the honest split.
For every one of these we build a purpose-engineered centrifugal fan in our own works — up to 2,25,000 m³/h, 2,000 mmWC, 425 HP and 500 °C. See the fan families →
Six numbers and one photograph get you a real selection instead of a catalogue page. If you do not have all of them, send what you have and we will work the rest out on a call.
Airflow in CMH and static pressure in mmWC or Pa, at the fan.
Type, motor rating, belt or direct drive, and whether a VFD is already fitted.
Hours per day, days per year, and how much of that is at reduced flow.
Rupees per unit. Without it there is no payback calculation, only a price.
Filter type, and pressure drop clean and loaded. This decides whether EC is viable at all.
At the fan, and the ambient in the plant room around it.
Fixed speed, 0–10 V or PWM, or a BMS interface — tell us which BMS.
Plenum dimensions, the door you have to get it through, and the supply available.
Selection, control and retrofit each have their own page, with the manufacturer’s data attributed model by model.
The duty data we need, how the fan behaves at part load, noise at your real duty point, and where EC is the wrong choice.
The signal window, the speed range, what your BMS actually sees, and what an array of fans gives you.
The eight checks we make on site before we will quote, what changes, what does not, and when a retrofit is the wrong answer.
EC stands for electronically commutated. It is a permanent-magnet brushless DC motor whose commutation is handled by electronics built into the fan itself. You get DC-motor efficiency with an AC-style connection, and the speed drive is already inside the unit - there is no separate VFD panel to buy, wire, house or cool.
Functionally both give you variable speed. The differences are practical. The EC controller sits on the motor, so there is no drive panel, no long motor cable and no separate commissioning step. A permanent-magnet rotor also holds its efficiency far better than an induction motor as you throttle back, which is where a ventilation fan spends most of its life. Where an AC fan with a VFD still wins is very large single duties, hot or abrasive air, and sites where a separately serviceable motor and drive are preferred. We will tell you which one your duty actually wants.
That depends entirely on your running hours, your tariff and how much of the time your fan runs throttled. The payback is calculated on your tariff, because a number worked out on someone else's tariff tells you nothing. Give us your duty point, your running hours and your electricity rate and we will work the arithmetic through with you.
Clean air only. Operating temperature is rated per model rather than across the range, and we state it against the model we are quoting. These fans carry aluminium or plastic impellers with an electronics package on board. Hot flue gas, abrasive or heavily dust-laden air, corrosive atmospheres and explosive atmospheres are all the wrong duty. For those we will quote you one of our own heavy-duty centrifugal fans instead.
Impellers run from 133 mm to 630 mm across three lines - a high-static-pressure range for paint booths and high-resistance air handling, a general AHU range, and a low-noise cleanroom range for filter and fan units. The sample set we hold covers roughly 3,055 to 23,515 cubic metres per hour with static pressure to about 1,832 Pa. We re-select to your actual duty point before quoting.
Usually yes, and it is often the strongest case. Several small EC fans in an array will go through a standard door where a single large replacement fan cannot be craned in, and the array gives you redundancy the original single fan never had. We survey the plenum, the duty and the access before committing to anything.
Yes. That is the point of buying it from us rather than importing it. Selection, landed cost, installation, commissioning and field service all sit with our own engineering and service teams at Ahilyanagar.
Deciding between an EC fan and an AC motor on a VFD? EC vs AC with a VFD →
Airflow, static pressure, running hours and your tariff. We will come back with a selection, a landed price and the payback worked on your own numbers — normally within three to five working days.*
Jitamitra Help Desk +91 8329172325 · sales@jitamitrablowers.com
*For our standard range. ATEX and special projects need 5 to 7 working days.
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