[ Mechanical ]
Chillers, air handlers, and the controls boundary. Three places a mechanical bid quietly loses its margin.
Equipment carries both the number and the lead time. A schedule that disagrees with its specification, a startup line excluded in the fine print, or a controls scope nobody claimed will each surface at buyout instead of on bid day.
The whole package, opened out.
Every document that governs a mechanical bid, and the ones that hide something.
- 00 21 13Instructions to bidders
- 01 11 00Summary of workMandatory site visit
- 23 05 00Common HVAC requirementsWarranty term
- 23 09 00Instrumentation and controlControls boundary
- 23 64 00Packaged water chillersCapacity conflict
- M-101Floor plans
- M-401Equipment schedulesCapacity conflict
- M-501Details
- ADD-03Addendum 3
9 documents in this mechanical package. 5 of them carry something that changes the number, and only one of those is a drawing.
Read the document, not the summary.
One extract from the mechanical documents, at the scale an estimator reads it.
| Mark | Service | Capacity | Stated by |
|---|---|---|---|
| CH-1 | Chilled water | 350 TON | Spec 23 64 00 |
| CH-1 | Chilled water | 400 TON | Drawing M-401Does not agree |
| AHU-1 | Supply air | 24,000 CFM | Agrees |
| P-1 | Condenser water | 1,200 GPM | Agrees |
What it catches in mechanical.
Each one cited to the document and page that proves it, so an estimator can verify it, price it, and approve the move.
- Schedule disagrees with the specSpec 23 64 00 · drawing M-401
The chiller schedule and the specification state different capacities. Priced either way, one of them is wrong, and the RFI has to go out before the number is set.
SCOPE GAP - Startup and TAB excludedVendor quote · fine print
Factory startup labor and test-and-balance sit outside the quoted price and inside the spec’s expectation. The gap is labor you already owe.
ADDED LABOR - Controls boundary claimed by nobodySpec 23 09 00 / Division 25
Integration to the building automation system reads as another trade’s scope in both sections. Two bidders exclude it and it lands on yours.
SPLIT SCOPE - Warranty term short by a yearSpec 23 05 00 §1.9
A one-year manufacturer warranty offered against a two-year requirement, extendable at a price that never appears on the quote.
WARRANTY GAP
Illustrative of the conditions this trade bids. Named pursuits, companies, and prices across this site are fictional.
Sector changes the clauses.
The same trade prices very differently depending on what is being built.
HealthcareAir change rates, pressure relationships, and phased shutdowns written into the spec rather than the drawings.
Data centersRedundancy language, CRAH counts, and the concurrent-maintainability clause that changes the equipment list.
EducationSummer shutdown windows and liquidated damages tied to the first day of term.
IndustrialProcess cooling loads carried in an appendix the invitation email never mentions.
Commercial officeTenant fit-out alternates priced separately and awarded together.
How ArosBid runs it.
Mechanical leveling turns on what the equipment quote excludes. ArosBid normalizes every vendor package to the same scope line, reconciles the stated total against its own itemization, and drafts the RFI when the two disagree.
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