RECD Installation Process: Step-by-Step Guide

Most people asking about RECD installation have already decided they need one. What they actually want to know is far more practical: how long is this going to take, who shows up on-site and when, what has to happen before the fitters arrive, and what happens afterward that isn’t just “installation done.” This guide walks through all three of those phases in order, using the timeline and sequence that a properly run installation actually follows, not the idealised version.

If you haven’t yet read how an RECD physically works, it helps to start with what an RECD is and how it works first, since a few terms here (DOC stage, DPF stage, backpressure) will make more sense with that context. This guide picks up from the decision to install and walks through to a compliant, documented, running unit.

Phase One: Before the Fitters Arrive

This phase is where most installation delays and most compliance headaches actually originate, not on installation day itself. Skipping or rushing any of these steps is the single most common reason an installation later fails inspection or has to be redone.

Step 1: Site and Generator Assessment

A qualified vendor needs to physically assess (or, at minimum, collect precise data on) your generator before fabricating anything. This includes the generator’s kVA rating, engine make and model, existing exhaust pipe diameter, chimney height and routing, available physical space around the exhaust run, and typical load profile (how many hours a day it runs, and at what percentage of rated load). Load profile matters more than most owners expect, because it determines whether your installation can rely on passive regeneration alone or needs an active-regeneration RECD, a distinction explained in our RECD mechanics guide.

This is also the point at which capacity and technology get matched. An RECD sized for a 125 kVA set cannot simply be scaled up or down for a 500 kVA set; it has to be engineered to the actual exhaust flow and backpressure characteristics of your specific generator.

Step 2: Technology and Vendor Confirmation

Before any fabrication begins, confirm in writing which CPCB approval the specific unit being fitted to your generator falls under, at what capacity band it was tested, and whether the approval documents name your vendor as the manufacturer or as a reseller of someone else’s approved technology. This is not a formality. A device that looks identical to an approved one but was not tested and approved for your generator’s capacity range will not hold up under a pollution control board inspection, a scenario we cover directly in how to verify a CPCB-tested RECD before it’s installed and in our separate guide on choosing a CPCB-approved vendor in the first place.

Step 3: Fabrication Lead Time

Because the RECD housing has to be built to match your generator’s exact exhaust geometry, this is not an off-the-shelf, same-day product in most cases. Fabrication typically runs two to four weeks depending on the vendor’s backlog, the capacity band (larger units generally take longer), and whether any custom ducting or mounting brackets are needed for a tight installation space. This is the step most owners underestimate when planning around a compliance deadline; if you have a fixed date by which your generator needs to be compliant, working backward from a four-week fabrication window, not a next-week one, is the safer assumption.

Step 4: Pre-Installation Documentation

While fabrication is underway, gather the paperwork that will be needed later: the generator’s existing Consent to Operate (or equivalent state pollution board consent), its electrical safety certificate, and any prior emission test reports. If your generator’s underlying regulatory paperwork isn’t current, the RECD installation itself can proceed, but the compliance filing that depends on it, discussed in Phase Three below, will stall until that paperwork catches up. If you are unsure where your generator’s NOC or registration status stands, our guides on getting a pollution NOC and on the DG set registration process in Delhi NCR cover that ground in detail.

Phase Two: Installation Day, Walked Through in Real Time

Here is what a properly run installation day actually looks like, hour by hour, on a mid-sized generator with reasonably accessible exhaust routing.

Morning, arrival and shutdown. The installation crew arrives with the fabricated RECD unit, mounting hardware, and documentation package. The generator is shut down and allowed to cool; exhaust components running at several hundred degrees Celsius cannot be safely worked on immediately after a shutdown, so this cooling window is non-negotiable and gets built into the schedule.

Mid-morning, existing exhaust section removed. The section of existing exhaust pipe and, where applicable, silencer that will be replaced or bypassed by the RECD housing is disconnected and removed. This is the point at which any mismatch between the fabricated unit and the actual on-site exhaust geometry becomes obvious, which is exactly why Step 1’s site assessment matters as much as it does. A unit fabricated from inaccurate measurements means delays here, not a clean fit.

Midday, RECD housing mounted and connected. The RECD unit is positioned, secured using mounting brackets fixed to the existing structure or a purpose-built support frame, and connected into the exhaust line on both the inlet (engine) side and outlet (chimney) side. Gaskets and clamps are checked for a proper seal, since even a small exhaust leak at this stage will affect both backpressure readings and emission performance later.

Early afternoon, sensor and wiring integration. Differential pressure sensors, temperature sensors, and, on active-regeneration units, the controller and any wiring to a power source are installed and routed. This is a more electrically involved step on active systems than on simpler passive-only units, and it is one reason active-regeneration RECDs generally take somewhat longer to install.

Mid-afternoon, leak and fitment check. Before the generator is restarted, the full installation is inspected for physical fit, secure mounting, and any visible leaks or loose fittings. On a straightforward mid-capacity installation, physical fitting from shutdown to this point typically takes one to three days total, not hours, once you include cooling time, multiple connection points, and careful leak-checking; larger, higher-kVA installations or ones with awkward exhaust routing can run longer.

Restart and initial run. The generator is restarted and run under load, with technicians monitoring exhaust temperature, backpressure, and for any abnormal noise, smoke, or vibration. This initial run is what surfaces installation problems (a loose clamp, an undersized gasket) before they become bigger issues weeks later.

Phase Three: After the Unit Is Fitted

Installation being physically complete is not the same as the process being finished. Three things still need to happen.

Step 5: Commissioning and Performance Verification

The vendor runs the generator through its paces, typically at multiple load points, and records exhaust temperature, backpressure, and, where testing equipment is available on-site, a basic smoke or opacity check. This is meant to confirm the installed unit is behaving the way its CPCB test data says it should, not just that it is physically bolted on correctly.

Step 6: Documentation Handover

You should receive, at minimum: the CPCB type-approval and test certificate for the specific RECD model installed, an installation and commissioning report specific to your generator (serial number, date, technician, readings recorded), and operation and maintenance guidelines for the unit. Keep every one of these; they are exactly what a pollution control board inspector will ask to see, a scenario described from the inspector’s side in what actually happens during a pollution control board inspection.

Step 7: Regulatory Filing

Depending on your state and, in the National Capital Region, your CAQM capacity band, the RECD installation typically needs to be reflected in your generator’s consent-to-operate record or filed through the relevant online portal, such as Delhi’s DPCC OCMMS system. This is the step that formally converts “we installed a device” into “our generator is on record as compliant,” and it is the step most often forgotten by owners who treat installation day as the finish line. If your generator’s broader registration paperwork isn’t current, this is also where that gap will surface; see our DG set registration guide if you need to close it.

Step 8: Building a Maintenance Routine

An RECD is not a fit-and-forget device. From the day it goes live, backpressure and temperature should be checked at whatever interval your vendor recommends (commonly tied to running hours rather than calendar time), and the filter stage needs periodic inspection for soot and ash loading. Our RECD maintenance guide covers cleaning methods, regeneration troubleshooting, and the warning signs that mean a service visit is overdue, and it is worth reading in full before your first scheduled check comes up rather than after something goes wrong.

Who Should Actually Be Present or Involved

Installation is not purely a vendor-side activity, and treating it that way is another common source of delay. At minimum, your facilities or electrical maintenance team should be available on installation day to coordinate the generator shutdown window, confirm power continuity plans if the generator is a primary backup source, and sign off on the commissioning readings alongside the vendor’s technician. If your site has its own electrical safety officer or a retained consultant handling pollution board liaison, loop them in during Phase One, not after installation is already complete, since they will often be the person who actually files the regulatory paperwork in Phase Three or coordinates with whoever does. For multi-tenant or managed facilities, it is also worth confirming in advance who has authority to approve a planned power interruption, since a one-to-three-day generator shutdown can affect building operations in ways that need sign-off beyond the maintenance team alone.

Installing RECDs Across Multiple Generators at One Site

Facilities with more than one diesel generator, common in hospitals, data centres, and large industrial sites, face a sequencing decision that a single-generator installation does not. Fitting every unit simultaneously maximises total downtime risk if something goes wrong across several sets at once, while fitting them one at a time stretches the overall compliance timeline. A middle path that works well in practice is to sequence installations so that at least one generator remains available as backup power at every point in the process, starting with whichever unit is easiest to take offline for the shortest period, and using the lessons learned on that first installation, exact fabrication tolerances, crew efficiency, any site-specific quirks, to make each subsequent installation faster. Vendors who regularly handle multi-unit sites will usually propose exactly this kind of staggered schedule without being asked, which is itself a reasonable signal of experience worth factoring into vendor selection, a topic covered in full in CPCB-approved RECD vendors: how to choose one.

Enclosed and Soundproof Generator Sets Need Extra Planning

If your generator sits inside an acoustic enclosure rather than an open frame, budget extra time in Phase One specifically for assessing how the RECD housing and its connecting ducting will fit within or route through the enclosure’s existing structure. This sometimes requires a cut-out modification to the canopy itself, which is a fabrication detail that needs to be resolved on paper before the crew arrives on-site, not improvised on installation day. Flag this explicitly with your vendor during the initial site assessment if your generator is enclosed, since it directly affects both the fabrication lead time and, in some cases, the installation-day duration.

Insurance and Warranty Paperwork Worth Sorting at the Same Time

Installation day is also a practical moment to update two pieces of paperwork that often get forgotten until they matter. First, if your generator’s insurance policy or your facility’s broader asset insurance schedule lists equipment specifications, update it to reflect the RECD as an added asset once installation is complete, since a claim involving generator damage down the line is a poor time to discover a coverage gap around recently added equipment. Second, if your generator itself is still under the original manufacturer’s warranty, confirm with that manufacturer, ideally before installation rather than after, that fitting a third-party RECD does not affect warranty terms on unrelated engine components; most manufacturers are comfortable with exhaust-side retrofits that don’t touch the engine internals, but getting this in writing avoids any ambiguity later.

What Separates a Rushed Installation From a Properly Run One

Across the phases above, a handful of habits reliably separate installations that go smoothly from ones that don’t. Properly run installations start with measurements taken in person by the vendor’s own technician, not phone-relayed estimates from the customer. They build fabrication lead time into the schedule with real buffer before any compliance deadline, rather than assuming the fastest-case timeline will hold. They involve the facility’s own maintenance or electrical team in scheduling the shutdown window rather than treating it as a vendor-only logistics detail. And they close the loop on regulatory filing explicitly, in writing, before installation day, rather than leaving it as an assumption that gets discovered to be nobody’s job weeks later. None of this is complicated, but all of it requires deliberately not skipping steps under time pressure, which is exactly when corners tend to get cut.

A One-Page Checklist

Use this to track where any given installation stands.

Before fabrication starts: generator kVA, engine make/model, and exhaust dimensions recorded; vendor’s CPCB approval confirmed in writing for this exact capacity band; existing Consent to Operate and electrical safety status confirmed as current.

During fabrication (2 to 4 weeks): fabrication timeline confirmed with the vendor in writing; installation date scheduled with enough buffer before any compliance deadline; site access and any permits for the installation crew arranged.

Installation day: generator safely shut down and cooled; old exhaust section removed without forcing a mismatch; RECD mounted, connected, and leak-checked; sensors and controller wiring completed and tested; initial run-up completed under monitored load.

After installation: CPCB certificate, test report, and installation report received and filed; performance readings from commissioning recorded for future comparison; regulatory filing (state consent or CAQM-linked portal, as applicable) completed; first maintenance check scheduled.

Common Mistakes That Delay or Derail an Installation

Measuring the exhaust line loosely instead of precisely. A housing built from rough estimates rather than exact measurements is the single most common cause of an installation-day mismatch that forces rework.

Scheduling installation with no buffer before a compliance deadline. Fabrication alone can take up to four weeks. Add installation, commissioning, and filing time, and scheduling installation for the week of your deadline leaves no room for anything to go wrong.

Treating physical installation as the end of the process. As covered in Phase Three, the regulatory filing step is what actually makes your generator compliant on paper. A perfectly installed RECD that was never filed with the relevant authority still leaves the generator technically non-compliant.

Not confirming the vendor’s approval matches the exact capacity band. An RECD approved for one kVA range does not automatically extend to another, even from the same manufacturer’s product line. This is worth verifying independently rather than taking a sales conversation’s word for it, as detailed in our vendor verification guide.

Losing the documentation. Certificates and reports handed over on installation day are frequently misplaced by the time an inspection happens months or years later. Store digital copies somewhere retrievable, not just the physical folder that came with the installation.

Frequently Asked Questions

How long does the entire RECD installation process take, start to finish? Realistically, two to five weeks from the initial site assessment to a fully commissioned, documented, and filed installation, with fabrication (two to four weeks) as the longest single stage. Physical fitting on installation day itself is usually one to three days depending on generator size and exhaust routing complexity.

Do I need to shut down my generator for the entire installation period? No. The generator only needs to be shut down for the physical fitting phase, typically one to three days, not for the weeks-long fabrication period beforehand, during which your generator continues running normally on its existing exhaust setup.

Can installation happen without a prior site visit? It is not recommended. Remote measurements taken by the owner rather than the vendor increase the risk of a fabrication mismatch, which then costs more time to correct than a proper site visit would have taken upfront.

Who is responsible for the regulatory filing after installation, the owner or the vendor? This varies by vendor agreement, so confirm it explicitly before installation begins. Some vendors include filing assistance as part of the installation package; others hand over documentation and expect the owner or their compliance consultant to complete the filing. Do not assume either way.

What if my generator’s existing Consent to Operate has already lapsed? Installing the RECD can still proceed, but the compliance filing in Phase Three will likely stall until the underlying consent is renewed. It is more efficient to address that gap before or alongside the RECD installation rather than after.

Does installation void my generator’s existing warranty? An RECD is fitted on the exhaust side and does not involve opening the engine, so it should not affect an engine manufacturer’s warranty in the way an internal engine modification would. That said, confirm this explicitly with your generator’s manufacturer or warranty provider before installation if the generator is still under warranty.

Can installation be done during a running compliance inspection deadline, or does it need to be complete beforehand? The full process, fabrication, fitting, commissioning, and regulatory filing, needs to be complete before a deadline for the generator to be considered compliant on record. Being mid-installation on the deadline date is generally treated the same as not having started, so plan backward from the deadline using the full multi-week timeline covered above, not just the one-to-three-day fitting window.

What happens if the commissioning readings don’t match the CPCB test data for the unit? This should trigger troubleshooting before sign-off, not after. Common causes include an exhaust leak at a connection point, an incorrectly sized housing for the actual exhaust flow, or a sensor calibration issue. A reputable vendor will resolve this before handing over final documentation rather than issuing a certificate that doesn’t reflect what was actually measured on-site.

What This Actually Costs, and Who to Have Do It

Installation mechanics are only half the picture. The other two questions worth answering before you commit are what the whole process costs for your specific capacity band, covered in how much an RECD costs in India, and how to tell a properly CPCB-approved vendor from one that isn’t, covered in CPCB-approved RECD vendors: how to choose one. If you already know your generator’s kVA rating, you can review Aceget’s CPCB-approved RECD range and get a quote based on your generator’s actual specification rather than a general estimate.