HVAC Duct Sizer is a professional utility for mechanical contractors to perform duct sizing calculations on iPhone and iPad.
Product velocity
Active
Daily rank 🇺🇸
—
Utilities
Sentiment
3.0
52 reviews
Nemesis
Fragmented field
The App DNA
What makes this app unique?
Users hire the app to replace manual ductulators with a portable, digital tool that enables on-site sizing and data sharing.
For HVAC contractors, installers, and technicians who require portable, on-site duct sizing and equipment tracking tools.
What does it look like?
Key features
Calculates duct dimensions based on airflow, velocity, or friction loss using the constant friction method.
Cloud-based storage for tracking equipment service records and location data, increasing B2B stickiness.
Emails inputs and results as HTML text and .CSV attachments for spreadsheet integration.
How much does it cost?
The iOS version utilizes a one-time purchase model, while the Android version serves as a lead generation tool.
Velocity
Active developmentShow more...
5 versions in history. Development pace: active.
Who built it?
Carmel Software
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HVAC RefChargeUser Sentiment
What do users think recently?
Fresh user feedback skews excited. Users appreciate mechanical contractors and hvac technicians rely on the app for daily duct sizing calculations in the field and the email reporting feature allows professionals to share accurate duct sizing data directly from job sites.
How are ratings & reviews evolving?
What users say, by theme
- Mechanical contractors and HVAC technicians rely on the app for daily duct sizing calculations in the field
- The email reporting feature allows professionals to share accurate duct sizing data directly from job sites
- Consistent updates over many years keep the tool relevant for long-term professional users on mobile devices
- Users report the interface stops scrolling after data entry, forcing a restart to view calculation results
27 of 27 recent reviews analyzed · moderate confidence · Excited overall
Read the full review analysisUnlock 2 more frustration themes and 1 user request, each backed by review evidence.
Access the full report for freeCompetition
Competitive landscape for HVAC Duct Sizer
How's the Utilities market?
The app maintains a 2.88-star rating across 27 reviews, indicating a stable but aging user base. The $5.99 price point creates friction against free supply-company alternatives.
Read the market outlookThe rivals identified
Unlock the deeper market read.
Access the full report for freeThe Analyst's Read
Key takeaways for HVAC Duct Sizer
Where is it heading?
The market for HVAC utilities is consolidating around free, manufacturer-backed tools that offer integrated design workflows. Carmel Software's reliance on a paid-upfront model leaves it exposed to these free entrants, so the PM must pivot to a feature-led retention strategy to prevent further churn.
- Persistent UI navigation bugs (screen locking) erode the daily active habit, which compounds the rating drag already visible on the platform.
- The lack of system-wide friction loss modes limits the app to individual duct runs, pushing power users toward more comprehensive design software.
- Consistent maintenance updates over many years sustain the tool's reputation as a reliable utility for long-term professional users.
The SWOT
- Trusted calculation engine replaces manual ductulators for daily field use
- Cloud-based equipment tracking provides a B2B retention mechanism for contractors
- Multi-year update cadence sustains relevance for long-term professional users
- Expand conversion modes to include fiberglass duct board and rectangular-to-round transitions
- Integrate system-wide friction loss calculations to capture full blower-system design workflows
Next best moves
Fix UI navigation lock because it is the top-reported frustration theme → improve rating baseline
+ 1 more prioritized moveThe counter-intuitive read
Users report: The app's paid-upfront model is not…
Read the full takeSince the last report: The app moved to a paid-upfront pricing model and repositioned its equipment tracking tool as a primary differentiator to defend against free industry alternatives.
Bottom line
Carmel Software maintains a loyal professional base through accurate, portable calculations, but the $5.99 price point is increasingly difficult to justify against free competitor tools, so the PM should prioritize fixing the UI navigation bug to defend the existing user base.
Unlock 3 critical frictions, 2 market threats, 1 more prioritized move and the analyst’s take.
Access the full report for freeFAQ
Is HVAC Duct Sizer worth paying for if free alternatives exist?
Does HVAC Duct Sizer work on both iPhone and iPad?
Is there a way to calculate total system friction loss?
Sources
Report last updated