September 20, 2026
Posted by: Aceget
Category: RECD & Emission Control Devices

A used RECD can be a sensible purchase, but only for a narrow kind of buyer and only after the unit passes a proper inspection. For everyone else, a lower sticker price hides costs that arrive later: a device that does not fit, a certificate that does not match your engine, a filter that is already tired, or an inspector who asks for paperwork nobody can produce.

This guide treats the decision like a visit to a scrap yard or a seller’s warehouse. Instead of arguing in the abstract, it walks you through four stages, from the paperwork you should demand before you leave home to the deal terms you should agree before you hand over money. There is a scorecard you can copy, a cost test that shows when a discount is real, and a list of situations where buying new is the safer call.

A retrofit emission control device is a compliance item first and a piece of hardware second. Keep that in mind throughout, because it changes how you judge every used listing you come across. If you need a refresher on the basics, start with what an RECD is and how it works or the overview of RECD costs in India.

What “Used RECD” Really Means

The phrase covers very different objects. Sellers rarely say which one they mean, so the first job is to find out.

Origin of the unit	What it usually is	Main risk
Removed from a scrapped or sold generator	A device that ran for years on another engine	Unknown condition and unknown history
Removed from a set that was upgraded	Often a younger device from a set replaced by a newer model	Certificate may be tied to a different engine family
Unused surplus or cancelled order	Never installed, sometimes stored for long	Age of the certificate, storage damage, missing papers
Demo or trial unit	Ran briefly for demonstration	Modified or repaired after trials
“Refurbished” or “reconditioned”	Cleaned, repaired, repainted, occasionally re-cored	Refurbishment may change what the certificate covers

Notice that only the third row has a natural claim to being “as good as new”, and even that depends on how it was stored. The word “refurbished” deserves special caution. A cleaned and repainted housing looks smart, but paint can also hide heat damage, and a cleaned filter element tells you nothing about cracks inside it.

If your interest is specifically in moving a device you already own from one set to another, our article on transferring an RECD to another diesel generator is the better companion. This guide is about buying from someone else.

Why the Idea Is Tempting, and What Buyers Overlook

The pull is obvious. Owners face a compliance deadline, a purchase order that has not yet been approved, or a tight budget. A used unit promises lower spending and a faster start.

What tends to be overlooked:

The device is only part of the bill. Transport, installation, mounting brackets, insulation, flange adapters, fitting time and testing all come on top. A used device that needs modification loses much of its price advantage.
Regulation is written around approved devices, not around metal. The Maharashtra Pollution Control Board circular, as summarised by TeamLease RegTech, requires that a retrofit device achieve at least 70 percent reduction of particulate matter and be certified by one of four CPCB-recognised facilities: ARAI Pune, ICAT Manesar, IP Dehradun or VRDE Ahmednagar. The board’s own notice page hosts the circular. What matters for a buyer is that the approval belongs to a tested device design for a defined engine range, so you need proof that the unit in front of you really is that design.
Time works against used hardware. Filters hold ash that does not burn away, catalysts age, housings corrode. Kirloskar’s RECD page quotes a design life of 10 to 12 years or 40,000 hours for its own device and a maintenance interval of about once every six months or 500 hours. Those figures apply to that maker’s product, but they show the scale: a used unit may already have spent a large share of its life.
Support disappears. A used device usually comes without a supplier who will answer if it fails, without a warranty and often without any performance guarantee.

None of this rules out a used unit. It simply means the inspection has to do the work that a new-device warranty would otherwise do.

The Yard Visit: Four Stages

Work through the stages in order. Each one has a stop rule. If a stage fails, do not move to the next; walk away or renegotiate.

Stage 1: The Paper Check (Before You Travel)

Most bad deals can be killed at this stage, from your desk, at no cost. Ask the seller to send clear photographs and copies of the following:

The manufacturer’s name and the device model
The device serial number, plate and any stamped identification on the housing
The CPCB-recognised laboratory test report or certificate, including the approved kW range and engine details
The original purchase invoice and installation certificate
The make, model, kVA rating and serial number of the generator it was last fitted to
Service and cleaning records, if any exist
The reason for sale

Then compare, line by line:

Identity match. The serial and model on the plate must match the paperwork. If the plate is missing, painted over or replaced, treat that as a serious warning. Our guide on how to verify a CPCB-tested RECD shows the checks to run, and how to read an RECD test certificate explains the fields.
Approved range versus your set. The certificate covers a specific band of engine power. For context, Aceget’s RECD page lists type approval bands of 15.03 kW to 119 kW, 110.7 kW to 250 kW and 330.3 kW to 797 kW for its own devices. A device approved for one band should not be assumed suitable for another.
Certificate age. Check the date of the test and any validity stated in the paper. If the certificate has no visible date or no laboratory name, ask for the original.
Source engine versus your engine. A device approved on one engine family may not suit a different one. Ask for the source engine details and compare them against your own nameplate. If you have not yet photographed your nameplate properly, our guide to DG nameplate photos for an RECD enquiry shows exactly what to capture.

Stop rule: If the identity does not match, or the seller cannot produce a certificate that names the device, stop. A device without traceable approval is metal, not a compliance solution.

Stage 2: Eyes On (At the Seller’s Yard)

Bring a strong torch, a phone camera, a tape measure, gloves, a dust mask and someone who understands generators if you can. Ash and soot from used filters should be handled with care, so do not blow into the device or shake out deposits.

Look for the following, roughly in this order:

Housing condition. Dents, patched holes, weld repairs, bulging panels, heavy corrosion or fresh paint over uneven metal all deserve questions.
Discolouration. Strong bluish or rainbow heat marks on stainless steel can mean it saw extreme temperatures. Ask why.
Inlet and outlet faces. Use the torch to look into the inlet. A healthy substrate face appears evenly dark and intact. Cracks, missing chunks, melted-looking patches or a sooty wet coating are bad signs.
Oil or fuel wetness. A shiny, oily film inside the device suggests the source engine burned oil or ran with heavy unburned fuel, which can foul the catalyst and the filter. Smell the housing gently from a distance. A strong oil smell is a warning.
Flanges and gaskets. Warped flanges, damaged studs and missing gaskets mean extra work and possible leaks.
Sensor ports and brackets. Missing ports, cut wires or damaged brackets suggest the device was removed roughly.
Weight. A device that feels much lighter than the listed specification may have had its internal element removed or replaced.
Ask to see it run, if it is still attached to a working generator. Note exhaust smoke, pressure readings if a gauge is fitted, and any smell or noise change under load.

Take photographs of everything, including the serial plate next to a newspaper or phone showing the date. If the seller refuses inspection or photography, that is your answer.

Stop rule: Visible cracking, melted or missing internal material, oil-soaked interiors, or refusal to allow inspection ends the purchase.

Stage 3: The Numbers (Match to Your Engine)

Paperwork and appearance can be fine while the fit is still wrong. Put the device beside your own generator’s data.

Engine power and kVA. Confirm that your set’s rated output falls inside the approved range in the certificate. If your nameplate and the paper disagree, work out why before any money moves.
Exhaust flow and back pressure. Every engine has a maximum exhaust restriction set by its maker. DieselNet’s page on engine exhaust back pressure reports that manufacturer limits for diesel generator sets typically fall between about 6.7 and 10.2 kPa. A device that is too small or already clogged pushes the engine toward that ceiling. Our article on how exhaust back pressure affects a DG set explains the effects on power, fuel use and temperature.
Physical fit. Compare flange size, inlet and outlet positions, overall length and weight against the space and exhaust routing at your site. Ask whether an adapter, a bend or a support frame will be needed.
Existing exhaust hardware. If your set already has a particulate filter or an SCR system, a used RECD may not belong on it at all. We cover that in whether an RECD can be added to a generator with an existing DPF or SCR.

Stop rule: If the device would sit outside the approved range for your engine, or you cannot establish that back pressure will stay within your engine maker’s limit, do not buy.

Stage 4: Deal Terms (Before You Pay)

Even a good unit can turn into a bad deal if the terms are loose. Agree these in writing:

Inspection right. You may have the device checked by your installer or a qualified technician before final payment.
Return or refund clause. Spell out what happens if your installer finds a defect, or if the pollution board or your inspector rejects the paperwork.
Document handover. Original certificate, invoice, installation record and any maintenance history, all handed over with the device.
Payment structure. Pay a deposit only. Release the balance after inspection and delivery.
Delivery and packing. Protect the substrate against knocks. Ceramic parts can crack in a rough transport.
Who installs and who signs off. Ask your installer to confirm in writing that they will fit a customer-supplied unit and issue an installation report. Many will not. Our list of common RECD installation mistakes and the step-by-step installation guide show what a proper job includes.
Warranty position. Ask the seller for any guarantee they will honour, even a short one. If they offer none, price that risk in.

Stop rule: If the seller will not put the identity of the unit, the source of the unit and the return terms on paper, walk away.

The Scorecard: Copy It, Fill It, Decide

Give each item a score from 0 to 2 (0 fails, 1 partly meets, 2 fully meets). Some items are hard stops: a zero on any of them ends the purchase whatever the total.

Item	Score (0, 1, 2)	Hard stop if zero?
Serial plate present and matching documents		Yes
Certificate names the device and a recognised laboratory		Yes
Approved power range covers your set		Yes
Certificate date and validity clear
Source engine similar to your engine
Housing free of cracks, patching and severe corrosion
Substrate face intact when inspected with a torch
No oil-soaked or fuel-soaked deposits
Flanges, gaskets and sensor ports intact
Physical dimensions fit your exhaust routing
Back pressure plausible for your engine		Yes
Invoice and installation history provided
Seller allows independent inspection		Yes
Written return terms
Installer willing to fit and certify the unit

How to read the total (maximum 30):

26 to 30: Strong candidate. Proceed to negotiation.
20 to 25: Possible, with a discount that reflects the missing items and a clear list of repairs.
Below 20: A new certified device is likely the better use of money.

The scorecard does not replace an expert’s opinion. It simply forces you to write down what you saw, which is the part most buyers skip.

The Cost Test: Is the Discount Real?

A used device is worth buying only if the all-in cost, adjusted for risk, is clearly below the cost of a new one. Use this test.

All-in used cost = purchase price + transport + inspection + modifications and adapters + installation + servicing to make it ready + reserve for early replacement

All-in new cost = quoted price including installation, certificate and warranty

The reserve is the piece buyers forget. Suppose there is a one in four chance that the used device fails early and must be replaced. Then the reserve for that risk is about one quarter of the cost of a replacement. It sounds cold, but it is the fair way to compare.

An illustrative example with round numbers (not real prices):

Line	Used device	New device
Purchase price	60	100
Transport	3	Included
Inspection and servicing	7	Included
Adapters and modifications	8	Included
Installation	10	Included
Risk reserve	15	0
Total	103	100

In this example the discount on the sticker vanished after everything was counted. The used device only wins if the numbers above shrink, for example if it needs no adapters, was recently cleaned by a competent workshop and carries a seller guarantee. The message is not that used is always worse. It is that a headline discount of 40 percent may leave only a small real saving, or none at all.

For a wider look at costs, including what drives them up or down, read our RECD cost guide and notes on subsidies, and compare against the cost of retrofitting an old set.

When a Used RECD Can Make Sense

There are a few situations where the balance shifts in favour of a used unit:

You own a second, identical generator and the seller is a known fleet owner who is retiring one of the same model. Matching engine, matching kW band and maintenance records may be available.
The unit is unused surplus from a cancelled order, with original packaging, plate, certificate and invoice intact.
You have a trusted installer willing to inspect, service and certify the device, and to stand behind the work.
The generator is nearing the end of its life and you only need a short compliance window before replacement. Even here, confirm with your State Pollution Control Board that a short-term arrangement is acceptable.
You are in a non-urgent position, so you can wait for the right unit instead of the nearest one.

When Buying New Is the Safer Choice

Buy new, or from a supplier who will certify and support the unit, when:

A compliance deadline, inspection or sealing risk is close. Our note on DG sets sealed for non-compliance shows what is at stake.
The generator serves a hospital, data centre or other critical load where downtime is costly.
Your generator is large and the device is heavy, expensive to transport and difficult to fit.
The unit’s certificate cannot be verified independently.
Your OEM warranty is still running and you want a clean paper trail. Read how an RECD can interact with your generator’s OEM warranty before deciding.
You want the vendor to be responsible for performance, back pressure and servicing.

A well-run supplier can also explain how to choose a CPCB-approved RECD vendor and stand behind the installation.

Red Flags at a Glance

Keep this list on your phone when you visit a seller:

No serial plate, or a plate that looks re-riveted or re-stamped
A certificate photograph that is blurry, cropped or missing the laboratory’s name
A story that keeps changing about where the unit came from
Pressure to pay today “because another buyer is coming”
Refusal to let your technician look inside the inlet
A device sold “without the ash” or “freshly cleaned” and no records to prove the cleaning
Fresh paint over weld marks or uneven surfaces
Extremely low price compared with new units of the same kVA range
Vague answers on the engine the unit ran on
No return terms, or terms that exclude every possible fault

After You Buy: Protect Yourself

If you go ahead, do the following in the first week:

Photograph and record. Keep a folder with the serial plate, certificate, invoice and photos from the yard.
Have the installer inspect it again on site before fitting, and note any change from what you saw.
Measure back pressure with the device fitted and the set at rated load, and store the reading. It becomes your baseline for future comparisons.
Ask the installer for a written installation report that names the device, the engine and the date.
Start a service log. Follow the routine in our RECD maintenance guide from day one.
Check with the State Pollution Control Board how they expect used devices to be documented. Requirements differ from state to state, and the CPCB genset notifications page is the place to look for central documents.

Also consider that buying a used generator brings similar traps. If you are shopping for the set as well, our second-hand diesel generator buying guide covers the engine side.

Frequently Asked Questions

Is it legal to install a second-hand RECD in India?

We did not find a public rule that either permits or prohibits the resale and reuse of an RECD as such. What the regulations do require is that a device be certified by a recognised laboratory and meet the stated particulate reduction. A used device therefore needs to be traceable to that certification, and you should confirm with your State Pollution Control Board how they treat reused devices before you buy.

How old can a used RECD be before it is not worth buying?

There is no single answer, because age matters less than hours, storage and condition. As one reference point, Kirloskar quotes a design life of 10 to 12 years or 40,000 hours for its own RECD, so a device that has already run many years or thousands of hours has less useful life left. Ask for hours, cleaning history and the source engine’s duty.

Can a used RECD be cleaned and reused?

Some filter elements can be cleaned by specialists, but cleaning cannot repair cracks or restore an aged catalyst. It also does not change what the certificate covers. Treat “cleaned” as one item to verify, not as proof of condition.

Will an installer fit a device that I bought elsewhere?

Some will and some will not. Installers carry responsibility for back pressure, mounting and sign-off, and many prefer to supply the unit themselves. Ask before you buy, and get their answer in writing.

Does a used RECD come with a warranty?

Rarely. The original warranty is normally tied to the first buyer and the original installation, so do not assume it transfers. If a seller offers a guarantee, ask what it covers and who honours it.

Summary

A used RECD is not automatically a bad idea, but it is a decision that rewards preparation. Start with the paperwork, then the inspection, then the numbers, then the deal terms. Use the scorecard to keep yourself disciplined, and use the cost test to see whether the discount survives contact with transport, adapters, installation and risk.

If the unit fails any hard stop, or if a deadline is close, a new certified device with a proper warranty and installation report will usually cost less in the end. If you would like help judging a specific unit, or a quote for a new device matched to your set, contact Aceget with your nameplate details or explore the RECD range for 25 kVA to 2500 kVA sets.

Is Buying a Used RECD a Sensible Option? A Four-Stage Yard Visit Checklist