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HVAC Lens

Tools For The Next Decision.

Nine tools for system checks, equipment questions, and contractor conversations.

Equipment Age

Goodman Age Finder

Read the serial number before weighing the next repair.

Open Tool & Guide Repair Or Replace

R-410A Repair Comparison

Put your repair quote and replacement options side by side.

Open Tool & Guide Room Sizing

12,000 BTU Room-Size Check

Compare room conditions and cooling capacity.

Open Tool & Guide Electrical Symptoms

AC Breaker Trip Checker

Use the timing of a trip to find the relevant guidance.

Open Tool & Guide Heating Choices

80% Furnace Decision Tool

Compare furnace efficiency and replacement scenarios.

Open Tool & Guide Refrigerant Alarms

A2L Alarm Checker

Understand the next questions to ask about a leak alarm.

Open Tool & Guide Thermostat Controls

Thermostat Limit Finder

Separate a temperature limit from a cooling fault.

Open Tool & Guide Contractor Research

Furnace Service Snapshot

Compare the published service details and verify them at the source.

Open Tool & Guide
Bench tool 01

Delta-T sanity check

Split-system cooling. Measure dry-bulb air temperature in the return grille and in a supply register at least six feet from the plenum, then compare the split against the target for your indoor humidity. A high split is an airflow symptom far more often than a refrigerant one.

Measured ΔT21.0 °F
Target band~18.0–22.0 °F
Deviation0.0 °F
Reading: in bandThe split is about where it should be for this humidity. If rooms are still uncomfortable, look at distribution and load before the equipment.
ReferenceCommon residential design targets
What you are checkingUsual target
Cooling airflow350–400 cfm per ton
Supply-to-return split at ~50% RH~18–22 °F
Rated total external static pressure0.5 in. w.c. (check the data plate)
Filter face velocityunder ~300 fpm
Return grille face velocityunder ~500 fpm

These are the ranges commonly published in residential HVAC design guidance and equipment literature, not measurements from your house. Figures marked ~ are approximate and vary with equipment, ductwork, and climate; the manufacturer's own data plate and target-split chart always win. Nothing here replaces a licensed contractor.