- October 11, 2026
- Posted by: Aceget
- Category: RECD & Emission Control Devices
You sent out a clear enquiry. You listed your DG set details, your exhaust layout, the certification you expect and the scope you want covered. Three offers came back, each one confidently stating “complied” against your requirements. Yet when you read them closely, one assumes a shorter exhaust run than your site has, one quietly excludes the support structure, and one offers a model whose certification covers a slightly different power range.
None of these are labelled as deviations. They are tucked inside assumptions, notes, exclusions and drawings. This is normal; vendors write offers to manage their own risk. Your job, as the buyer, is to find every place where an offer departs from what you asked for, decide whether that departure matters, and fix it in writing before the purchase order. This article gives you a repeatable method to do that for RECD technical offers.
What Counts as a Deviation?
A deviation is any point where the offered product, scope, service or condition differs from your enquiry specification. It does not have to be called a deviation to be one. In RECD offers, deviations usually come in four forms.
| Type | How it appears | Example |
|---|---|---|
| Declared deviation | Listed in a “Deviations” or “Exceptions” section | “Insulation of RECD body not in our scope.” |
| Embedded deviation | Hidden in assumptions, notes or drawings | Drawing shows 3 m exhaust run; site has 9 m. |
| Silent deviation | Requirement simply not addressed | Enquiry asks for alarm panel; offer never mentions it. |
| Soft compliance | “Noted,” “Will comply if feasible,” “As per standard practice” | “Backpressure: noted.” |
Treat silent deviations and soft compliance as non-compliance until the vendor confirms otherwise in writing. “Noted” means the vendor has read your requirement. It does not mean they will meet it.
Before You Start: Prepare a Clean Baseline
You cannot spot deviations without a clear reference. Before reviewing offers, make sure your own specification is complete and numbered. At a minimum, it should cover:
- DG set and engine data: make, model, kVA, gross kW, serial number, aspiration and engine emission stage
- Operating conditions: load profile, duty, fuel and ambient conditions
- Exhaust configuration: pipe size, length, bends, silencer and existing backpressure
- Certification requirement for the offered model
- Scope of supply and services, item by item
- Testing requirements: FAT, SAT and any site emission test
- Documentation to be handed over
- Warranty, performance guarantee and service expectations
If your enquiry was thin, deviations will be hard to judge because there is nothing firm to deviate from. Our articles on nameplate photos for an RECD enquiry and using OEM exhaust flow data to specify an RECD help you strengthen the baseline. For a structured approach to operating conditions, see RECD performance guarantees: which operating conditions must be defined.
The Seven-Step Deviation Review Method
Step 1: Read the Whole Offer, Including the Boring Parts
Deviations rarely sit on the summary page. Read the cover letter, technical data sheet, drawings, scope of supply, terms and conditions, assumptions, notes, exclusions and any attached brochures. Brochures matter because some offers state “as per enclosed catalogue,” which pulls in every limitation printed in that catalogue.
Step 2: Build a Clause-by-Clause Compliance Matrix
List each numbered requirement from your specification in rows. For each vendor, record exactly what the offer says, the page reference and your assessment. This forces every requirement to be checked against every offer, which is how silent deviations come to light.
| Spec ref | Requirement | Vendor response (verbatim) | Offer page | Assessment |
|---|---|---|---|---|
| 3.1 | Certified for engine gross power range covering our engine | Complies / Deviates / Unclear | ||
| 3.4 | Total system backpressure within engine OEM limit at rated load | |||
| 4.2 | Supply of supports and flexible bellows | |||
| 5.1 | Witnessed FAT | |||
| 6.3 | Handover of certification copies and O&M manual |
Step 3: Hunt for Embedded Deviations
Once the matrix is filled, go back to the assumptions, notes and drawings. Ask of each sentence: “If this is true, does it change what I asked for?” Common embedded deviations in RECD offers include:
- Assumed exhaust length, number of bends or pipe diameter that differs from your site
- Assumed load profile, such as “minimum 50% load,” when your set often runs lower
- Assumed fuel, such as a specific sulphur level, without saying what happens otherwise
- Assumed availability of scaffolding, cranes, power or welding facilities from the buyer
- Assumed site readiness by a date that is not realistic for you
- Drawing dimensions that clash with your available space or service clearance
Our guides on service clearance around an RECD, reusing existing exhaust pipework and installing without cutting the existing pipe help you check drawings against site reality.
Step 4: Classify Each Deviation
Not all deviations deserve the same attention. A simple three-level classification keeps the review focused.
| Class | Definition | Typical RECD examples | Default response |
|---|---|---|---|
| Critical | Affects compliance, safety or engine protection | Model not certified for your engine’s power range; backpressure guarantee missing; no warranty on filter element combined with a high replacement cost | Must be resolved or the offer is technically unacceptable |
| Major | Affects cost, schedule or long-term performance | Supports or insulation excluded; FAT not offered; cleaning interval based on unrealistic load | Resolve, or quantify the cost and add it to the offer price for comparison |
| Minor | Administrative or cosmetic | Paint colour; document format; different but equivalent gasket material | Accept, recording the acceptance |
Step 5: Ask, Do Not Assume
For every “Unclear” or “Deviates” entry, send a written technical clarification query. Keep questions closed and specific so answers can be compared. “Please confirm whether supports are included” is better than “Please clarify scope.” Set a reply deadline and ask vendors to answer in the same numbered format.
Use the same questions for all vendors on common issues. This is both fair and practical: when every vendor answers the same question, their replies line up neatly in your matrix.
Step 6: Normalise the Offers
Once clarifications are back, some deviations will have been withdrawn and others confirmed. For confirmed major deviations, put a price on them so offers can be compared on equal terms. This is often called bid loading.
- If one vendor excludes supports and bellows, add your estimated cost for those items to that vendor’s price
- If one vendor excludes travel for warranty visits, estimate likely visits over the warranty period and add the cost
- If one vendor’s filter element is a consumable with a stated replacement interval, add the expected replacement cost over your evaluation period
- If one vendor does not offer FAT, consider the cost of a third-party inspection
Normalised prices regularly change the ranking of offers. The cheapest quote on paper is often not the cheapest once deviations are costed. Our guide on RECD cost in India gives you reference points for these estimates.
Step 7: Close Out in a Signed Technical Agreement
The final step is to record every resolved deviation in a single document, often called minutes of the technical meeting, a technical agreement or an agreed deviation list. Attach it to the purchase order and state that it overrides any conflicting statement in the original offer. Without this, the vendor’s original assumptions can resurface during execution.
Where RECD Offers Most Often Deviate
Experience across many retrofit projects shows certain areas attract deviations more than others. Give these extra attention.
Certification Coverage
Check that the offered model’s certification covers your engine’s gross power and type. An offer that states “CPCB approved” without naming the model, the certificate number and the power range should be treated as unclear. Cross-check with the official sources on the CPCB website, and for the NCR, the directions issued by CAQM. Our articles on verifying a CPCB-tested RECD and reading an RECD test certificate explain what to look for. For imported engines, see retrofitting RECDs on imported diesel generators.
Backpressure Basis
Many offers state the clean pressure drop across the RECD alone, while your requirement is total system backpressure within the engine OEM limit. These are not the same. Confirm which figure the vendor is guaranteeing and at what flow. Background reading: how exhaust backpressure affects a DG set.
Silencer Treatment
Some offers propose removing or replacing the existing silencer to save backpressure, sometimes without saying so explicitly in the scope. That can change noise levels and acoustic compliance. Read whether an RECD can replace a generator’s exhaust silencer before accepting such a proposal.
Scope Boundaries
Typical grey areas include supports and structural steel, flexible bellows, insulation and cladding, sensor wiring to a remote panel, scaffolding and lifting, civil works, disposal of removed pipe sections and permits for hot work. Each one should be marked clearly as in the vendor’s scope or yours.
Testing and Documentation
Check whether FAT is offered at all, whether it can be witnessed, which load steps SAT covers and which documents are handed over. Our article on Factory Acceptance vs Site Acceptance Tests for RECD projects shows what a complete test scope looks like.
Warranty and Guarantees
Compare warranty start dates, filter element cover, labour inclusion and exclusions. Our guide on RECD warranty terms: parts, labour and exclusions provides a full comparison sheet.
Commercial Terms Inside the Technical Offer
Payment terms, validity, delivery periods and price escalation sometimes sit inside technical documents. They should be reviewed with the commercial offer. Our article on structuring RECD payment milestones around project deliverables helps you judge whether payment terms conflict with your test and acceptance plan.
Five Disguised Deviations and How to Respond
1. “Supply of RECD as per enclosed drawing.” The drawing shows only the RECD body with flanges. No supports, no bellows, no transition pieces. Response: Ask the vendor to list all items in the scope of supply, item by item, and confirm whether supports, bellows and adaptors are included.
2. “Backpressure will be within permissible limits.” No figure, no load, no reference to whose limits. Response: Ask for the guaranteed maximum total system backpressure at rated load, measured at stated points, compared with the engine OEM’s limit.
3. “Installation assuming free access and lifting arrangement by client.” On a rooftop installation, this shifts crane hire to you. Response: Ask for a lump-sum price including lifting, or a firm daily rate, and record the agreed responsibility. See rooftop installation, structural support and lifting access.
4. “Suitable for DG sets up to 250 kVA.” Your set is 250 kVA, but the engine’s gross power is near the top of the certified range for that model. Response: Ask for the certification reference with the exact gross power range and confirm in writing that your engine’s gross power falls within it.
5. “Maintenance: cleaning every 500 hours (typical).” The word “typical” hides the assumed load profile. If your set runs mostly at low load, cleaning may be needed far sooner. Response: Ask what load profile the interval assumes and what interval applies at your declared profile. Our guide on choosing an RECD for low-load running is useful context.
A Deviation Register Template
Keep all deviations for one enquiry in a single register. It becomes your audit trail if questions arise later from management, auditors or regulators.
| No. | Vendor | Spec ref | Deviation description | Class | Clarification sent / received | Resolution | Cost impact | Status |
|---|---|---|---|---|---|---|---|---|
| D-01 | Vendor A | 4.2 | Supports and bellows not included | Major | Sent / Received | Vendor agreed to include | Nil | Closed |
| D-02 | Vendor B | 3.4 | Backpressure stated for RECD only | Critical | Sent / Pending | Open | ||
| D-03 | Vendor C | 6.3 | O&M manual in English only | Minor | Not required | Accepted | Nil | Closed |
Sample Clarification Letter
Adapt this to your own format. Keep it short, numbered and specific.
“Subject: Technical clarifications on your offer ref. [__] dated [__] for RECD for [__] kVA DG set. With reference to your offer, please provide written responses to the following by [date], quoting the same numbering: (1) Please state the certification reference, model and gross power range for the offered RECD, and confirm our engine’s gross power of [__] kW falls within it. (2) Please confirm the guaranteed maximum total exhaust system backpressure after installation at rated load, and the measurement points. (3) Please confirm whether supports, flexible bellows, transition pieces and insulation are included in your scope. (4) Please confirm the load profile assumed for the stated cleaning interval, and the expected interval at our declared profile of [__]. (5) Please confirm availability of a witnessed Factory Acceptance Test. Any requirement not specifically confirmed will be treated as not offered.”
The final sentence matters. It tells the vendor that silence will be read as non-compliance, which encourages complete answers.
Common Mistakes When Reviewing Deviations
- Reviewing only the deviation list. The most consequential deviations are usually embedded elsewhere.
- Accepting verbal clarifications. Phone calls and meetings are useful, but every outcome should be confirmed in writing.
- Allowing the latest document to override everything. If the vendor’s revised offer reintroduces an old assumption, the earlier agreement can be lost. State clearly which document prevails.
- Comparing prices before normalising. A low price with major exclusions can look attractive until costs are added back.
- Not involving the right people. Your DG maintenance contractor or engine OEM can quickly spot engine-related assumptions that a procurement team might miss.
For more on avoiding project pitfalls, read common RECD installation mistakes to avoid and questions to ask before choosing a generator dealer.
Technical vs Commercial Deviations: Who Reviews What?
RECD offers often mix technical and commercial content, and deviations can slip through the gap between departments. A clear split of responsibility helps.
| Deviation area | Primary reviewer | Supporting reviewer |
|---|---|---|
| Model, certification and power range | Compliance or EHS lead | Facility engineer |
| Sizing, backpressure and exhaust layout | Facility or maintenance engineer | DG service provider |
| Scope of supply and site works | Facility engineer | Procurement |
| Testing, documentation and training | Facility engineer | Compliance lead |
| Warranty and performance guarantee | Procurement | Facility engineer |
| Payment, delivery, validity and escalation | Procurement or finance | Project lead |
For smaller organisations, one person may wear several of these hats. That is fine, as long as each area is consciously reviewed rather than assumed to be someone else’s job. In housing societies, for example, a committee member with an engineering background can take the technical rows while the treasurer covers the commercial ones.
Reviewing Revised Offers Without Losing Ground
After clarifications, vendors usually submit a revised offer. This is where previously settled points can quietly reappear. Revised offers are often produced by editing an older template, and old assumptions or exclusions can survive the edit.
- Compare line by line: Put the revised offer next to the previous version and your deviation register. Check every closed item is reflected correctly.
- Look for new notes: A revised price is sometimes accompanied by a new assumption that offsets the concession.
- Confirm drawing revisions: If the agreed change affects layout, the drawing revision number should change too.
- Check validity dates: A revised offer may carry a shorter validity period, putting pressure on your approval timeline.
- Freeze the baseline: Once you are satisfied, state in writing that the revised offer, read together with the signed deviation list, is the final basis for the order.
This discipline is especially important on multi-site or multi-set orders, where several revisions may circulate within a few weeks. A single, frozen baseline prevents the installation team from working off an outdated document.
How Long Should a Deviation Review Take?
For a single standard retrofit, a careful review and one round of clarifications usually fit within a week or two. For multi-set projects or critical facilities, plan for two rounds of clarification and a technical meeting. The time is well spent: deviations caught at offer stage cost an email to fix, while the same deviations discovered at installation cost days of delay and often a variation order. If compliance deadlines are tight, as they can be ahead of the winter season in the NCR, start the review early. Our articles on GRAP stages 1 to 4 and the RECD installation timeline help you plan backwards from your deadline.
Quick Deviation Review Checklist
- Is my enquiry specification complete, numbered and shared identically with all vendors?
- Have I read every page of each offer, including notes, drawings and catalogues?
- Does my compliance matrix have an entry for every requirement against every vendor?
- Have I listed every embedded assumption and checked it against site reality?
- Is every deviation classified as critical, major or minor?
- Have all unclear and soft-compliance responses been converted into written clarification queries?
- Are confirmed major deviations costed and added to the offer price for comparison?
- Has the revised offer been compared line by line with the deviation register?
- Is there a signed deviation list that overrides the original offer?
- Is that list attached to the purchase order?
Frequently Asked Questions
Is “noted” an acceptable response to a technical requirement?
No. “Noted” only acknowledges the requirement. Ask the vendor to state clearly whether they comply, and if not, what they offer instead.
Should I reject an offer that has deviations?
Not automatically. Most offers contain some deviations. Classify them, clarify the unclear ones and reject only if critical deviations cannot be resolved.
How do I compare offers with different exclusions?
Estimate the cost of each excluded item you will need anyway and add it to that vendor’s price. Then compare the normalised totals.
Who should be involved in reviewing an RECD technical offer?
Ideally your facility or maintenance engineer, procurement, your compliance or EHS lead and, where possible, your DG service provider.
What document should record the agreed deviations?
A signed technical agreement or minutes of meeting, attached to the purchase order and stated to take precedence over conflicting statements in the original offer.
Conclusion
Reviewing deviations is not about catching vendors out. It is about making sure both sides are agreeing to the same project before money and time are committed. Build a clean baseline, check every clause, hunt for embedded assumptions, classify what you find, ask precise questions, cost what remains and record the outcome in one signed document. Do that, and your RECD project will start from a shared understanding rather than a set of hidden surprises.
Aceget technical offers list scope, assumptions and deviations clearly so you can review them quickly. Explore our Retrofit Emission Control Devices, see our certifications or request an offer for your DG set.