Independent HVAC & water heater guides

Clear Answers for Your Heating, Cooling & Hot Water

Step-by-step troubleshooting, water heater manuals made simple and free HVAC calculators — written by HVAC specialist David Clark and checked against manufacturer documentation.

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David ClarkWritten by David Clark · Founder & HVAC specialist, 10+ years in residential and light-commercial systems
Start With the SymptomDiagnose
No Hot Water After a Power OutageWater heatersHot Water Smells Like Rotten EggsWater qualityRusty or Discolored Hot WaterWater qualityBradford White Aero Error CodeTroubleshootingRepair or Replace My HVAC System?HVAC

Smell gas? Leave the building now and call your gas utility or 911 from outside.

Manufacturer-CheckedSpecs and steps verified against official manuals and documentation.
Safety FirstWe flag gas, electrical and refrigerant work that needs a licensed pro.
Free CalculatorsSizing, SEER savings, superheat and duct tools — no sign-up.
Kept up to DateGuides are reviewed and updated when products or standards change.

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Water HeatersHot water problems, water quality, safety sensors and smart heaters.Browse guides Bradford WhiteManuals, specs, recovery times, error codes and maintenance.Browse guides HeatingFurnaces, radiant vs. forced air, zone heating and running costs.Browse guides HVAC GuidesSystem sizing, ductless vs. central air, maintenance and repairs.Browse guides NavienTankless water heater guides, error codes and maintenance.Coming soon Beginner’s RoadmapNew to HVAC? A structured path through the fundamentals.Learning path

Free HVAC calculators

Run the Numbers Before You Call a Contractor

Quick estimates to help you ask better questions. For final equipment selection, a contractor should complete a full Manual J / D load and duct calculation.

All calculators
All-in-One Load & System PerformanceEstimate heating and cooling loads and check how a system should perform — in one place.Open calculator HVAC System SizingBallpark the tonnage or BTU capacity for a home before you get quotes.Open calculator SEER SavingsCompare efficiency ratings and estimate yearly energy savings.Open calculator AC SuperheatWork out superheat from line temperature and pressure readings.Open calculator Duct Sizing & Airflow (Manual D)Size supply and return ducts for the airflow each room needs.Open calculator

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David Clark, founder of HVACrly Author & reviewer

Who’s behind HVACrly

Hi, I’m David Clark

I founded HVACrly to make heating, cooling, ventilation and refrigeration easier to understand. I’ve spent more than ten years working on residential and light-commercial systems, and I write each guide around the questions homeowners ask most.

About David Editorial policy

How every guide is made

Our 4-Step Process

  1. ResearchStart from manufacturer manuals, spec sheets and installation instructions for the exact product or system.
  2. Write for Real HomesExplain what to check, in what order, and what each result means — in plain language.
  3. Safety ReviewMark the steps that involve gas, high voltage, refrigerant or scalding water, and when to call a pro.
  4. UpdateRevisit guides when models, codes or efficiency standards change, and fix reported errors.

Safety first

Know When to Stop DIY and Call a Licensed Pro

Many HVAC and water heater fixes are safe for homeowners. These situations aren’t — our guides always flag them.

Read our safety disclaimer
Gas Smell or Suspected LeakDon’t use switches or phones inside. Leave, then call your gas utility or 911.
Carbon Monoxide AlarmGet everyone outside into fresh air and call 911 or your fire department.
Burning or Electrical SmellSwitch the system off at the breaker and have it inspected before reuse.
Refrigerant WorkIn the US, handling refrigerant requires EPA Section 608 certification.
Leaking Relief ValveA dripping T&P valve can signal dangerous pressure or temperature.

FAQ

Questions About HVACrly

Can’t find what you need? Search the site or send us a message.

Contact us
What Is HVACrly?

HVACrly is an independent website with practical guides to heating, cooling, ventilation, refrigeration and water heaters, plus free HVAC calculators. It’s written for homeowners, DIYers and people starting out in the trade.

Who Writes the Guides?

Guides are written and reviewed by David Clark, founder of HVACrly. Read about our research and update process in the editorial policy.

Are the Calculators Free?

Yes. Every calculator is free and runs without an account. Results are estimates — a contractor should confirm sizing with a full load calculation before you buy equipment.

Do You Sell Equipment or Repair Services?

No. HVACrly doesn’t sell HVAC equipment or repair services, and we’re not affiliated with the manufacturers we cover. See how the site is funded in our affiliate & advertising disclosure.

Can These Guides Replace a Technician?

No. They help you understand a problem and decide on next steps. Work involving gas, high-voltage electricity, refrigerant or venting should be done by a licensed professional.

Can I Ask a Question or Report an Error?

Yes — use the contact page. Include your equipment brand, model and the symptom, and we’ll use it to improve our guides.

Stuck on a Heating, Cooling or Hot Water Problem?

Tell us the brand, model and symptom. We’ll point you to the right guide — and suggest new ones based on reader questions.

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