For US commercial hvac contractors

Follow HVAC revisions from equipment to bid scope.

An equipment schedule can change while a floor plan looks the same. Keep revised equipment requirements, distribution layouts and controls notes together when reviewing the mechanical scope of your bid.

Your review. Your project data.

Keep your team in control.

RevisionSignal supports your judgment. It may miss changes, and a finding still needs your review.

Keep professional review in place.

Early Access starts in Shadow Review. Verify findings against the source and continue your normal review process.

Start with a conversation.

Describe your workflow in the access request. Leave out confidential drawings, specifications, and bid details.

Agree on data handling first.

Before sharing live files, confirm who can access them, which providers process them, and the retention and deletion terms.

A real HVAC bid example

See what changed.
Know what to review.

Norfolk Middle School

Fluid Cooler Replacement · HVAC

Addendum 2 · March 27, 2026

Manually reviewed example

Focused detail of original M0.0 Fluid Cooler Schedule remark 6: 650 GPM, EWT 102°F, LWT 90°F, and 40°F ambient conditions. — Schedule remark 6: dry-operation LWT is 90°F.
Before PDF · page 2 (opens in a new tab)

Focused detail of Addendum 2 M0.0 remark 6: source revision cloud around LWT 93.13°F; 650 GPM, EWT 102°F and 40°F ambient remain unchanged. — The same dry-operation condition now specifies LWT 93.13°F.
After PDF · page 4 (opens in a new tab)

Red outline: selected change. Dashed outline: corresponding area before the change. Focused detail of schedule remark 6. Black revision cloud: part of the source drawing.

Show source context

Read the surrounding source text. Open either crop at full size to zoom in on small text.

Original M0.0 schedule context. Full remark 6 requires 650 GPM, EWT 102°F and LWT 90°F at 40°F ambient without spray water operation. The FC-1 schedule tag is visible below. — Remark 6 includes the full requirement for operation without spray water. The FC-1 schedule tag is shown below the remarks.
Open full-size source crop: Before, Original bid set, M0.0 (opens in a new tab)

Addendum 2 M0.0 schedule context. Full remark 6 requires 650 GPM, EWT 102°F and LWT 93.13°F at 40°F ambient without spray water operation. The changed LWT has a source revision cloud. — The same remark 6 now specifies LWT 93.13°F for operation without spray water. Other source revision clouds are also visible in this wider context.
Open full-size source crop: After, Addendum 2, M0.0 (opens in a new tab)

What changed
Dry-operation leaving-water temperature changes from 90°F to 93.13°F. Flow, entering-water temperature and ambient temperature are unchanged.
Why it may matter
The equipment selection needs checking against this revised operating condition. The main schedule row is unchanged.
What to review
Have the supplier verify the quoted fluid cooler against remark 6 and the full schedule and specifications.

One manually reviewed change. Not an automated product result or a complete list of addendum changes.

Unaltered source crops · Norfolk Public Schools bid documents (opens in a new tab) · Drawings © Morrissey Engineering, Inc.

HVAC review scenarios

What a revision can change.

These scenarios describe the review workflow we are developing. They are not automated findings or a statement of currently supported detection coverage.

Equipment schedule revisions

Changes to an AHU, RTU, fan or other scheduled unit may alter the equipment selection and its listed requirements.

Review in context

Compare the full schedule row, notes and specification references, rather than checking the model tag alone.

Ductwork and distribution

A changed duct size, route, diffuser or damper can affect material quantities and installation assumptions.

Review in context

Review the drawing at the changed location and check connected details, access requirements and scope notes.

Controls, testing and coordination

New control sequences, interfaces or testing requirements may add work without adding a visible equipment symbol.

Review in context

Check the controls narrative and responsibility assignments, including work shared with electrical or fire alarm contractors.

Start with the right documents.

Use the mechanical plans, equipment schedules, duct and piping details, control sequences, specifications and addenda. Keep referenced electrical requirements and testing or balancing requirements available for coordination review.

Your team stays in control. Verify source documents and continue your normal bid review.

Before you join

HVAC review, explained.

Can we use RevisionSignal for an HVAC bid now?

HVAC support is planned. Register interest to discuss your workflow and potential pilot participation. Mechanical review coverage will be validated before access is offered.

Will this calculate airflow or size equipment?

The proposed product highlights document changes and their sources. It does not perform mechanical design, certify equipment sizing or replace an engineer’s review.

Why include controls and balancing documents?

Scope can change through a control sequence, interface requirement or testing obligation even when the plan geometry is unchanged. Those documents help your estimator understand the revision in context.

HVAC · Planned