How to Pass Load Calc Requirements for a Permit
Inspectors are rejecting rule-of-thumb sizing. Here’s what a permit-ready ACCA Manual J submittal actually has to show — and how to produce one without stalling the job.
By Chris Morin
HVAC Pro Blog Since 2012
Home Performance: Combustion Powered Ventilation?
Why a basement gets more humid after a furnace replacement — the combustion air a Category I appliance had been quietly exhausting.
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Oil Tanks in Your Home
Finding a leaking oil tank in a basement: the plan, the magnetic patch kit, and what to tell the homeowner before the next delivery.
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Mold in a Ductless Heat Pump?
A ductless head is cold, dark and moist. Prevention first, then the cleaning practice that actually works.
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Sleep through the Static
A correctly designed duct system and two uncomfortable rooms years later. Static pressure measurement as the diagnostic that finds it.
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Dirty Socks in the Attic?
Constant fan, cycling thermostats and UV lights all stop dirty sock syndrome, and none of them run on demand. A better answer.
Read article arrow_forwardDIY Ductless: Which side are you on?
Friedrich’s DIY mini-split argued from both sides — the HVAC professional’s case against, and the energy geek’s case for.
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Frost Proof Flare Nuts Required!
Cut the flare nuts off the line set. Why a ductless refrigerant circuit needs the frost-rated nuts the manufacturer supplies.
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Under Pressure
Calculating design friction loss from available blower static pressure and total equivalent length — before the ductwork goes in, not after.
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MA/RI Code: Interior Design Conditions
Massachusetts and Rhode Island code sets the indoor design conditions you size to — and the minimum is the worst case the law allows.
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Realistic Expectations & “The Occupied Zone”
The occupied zone and radiant asymmetry, put in the terms you can actually use to set a homeowner’s expectations during the sale.
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Top 5 A/C Code Requirements not Enforced
Five code requirements inspectors have rarely enforced and are now starting to fail permits over. Lead, or wait to be caught.
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Please, Make the Transition!
Return duct sizing has improved in New England. The rule of duct design still being ignored, and what it costs in static pressure.
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UPDATED: Big Changes for Duct Testing in MA
Massachusetts requires testing on new and altered duct systems statewide. What the code says, and what the permit structure quietly costs you.
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Should this Duct Layout be Banned?
Ducts run tight against the roof deck: the CFM is not the problem, the delivered dry bulb temperature is.
Read article arrow_forward5 Resources I Read / Listen to Every Week
The original list: five podcasts and books worth a standing weekly slot, chosen mostly from outside the trade.
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Marketing: Buy a Hotdog, Mister?
A contractor with no leads in the hottest week of the year, and the marketing plan that turned out never to have existed.
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On Call for the Holidays?
Twenty years of holiday on-call rotations, the 4:30pm Christmas Eve no-heat call, and how the duty has changed.
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A/C a Necessity in New England?
Air conditioning went from luxury to necessity in a single generation in New England. What that shift means for how you sell it.
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PED’s for the HVAC Tech
If a pill existed that inflated a technician’s numbers, would you take it? A thought experiment that lands on training.
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“There can be no Economy where there is no Efficiency”, Benjamin Disraeli
A Victorian prime minister’s line on efficiency, and what it still explains about how homeowners buy energy improvements.
Read article arrow_forwardSome Handicaps Cannot Be Seen
A veteran’s account of four years fighting a VA claim, and what it took before the department treated the illness seriously.
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Work/Life Balance in HVAC?
Leaving a nephew’s birthday party for an emergency call, and the moment a service manager decides the trade will not cost him his family.
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The Value of an Experience
Front row versus lawn seats at the same concert, and what that gap explains about pricing a comfort system.
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Don’t Heckle Nice Ladies! – Guest Blogger, Elaina Burdick, EB&L Marketing
Guest post by Elaina Burdick: what a heckler at an ACCA chapter meeting taught her about online reputation before reviews were taken seriously.
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5 Continuing Education Rules for Students
Five rules for adult HVAC classes, written from a decade of teaching them — and why the offender is rarely the one derailed.
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5 Resources I Read / Listen to Every Week – 2020 Edition
The 2020 edition of the weekly reading and listening list, drawn mostly from outside the trade on purpose.
Read article arrow_forward5 Resources I Read / Listen to Every Week – 2021 Edition
The 2021 list: five books, podcasts and newsletters worth a standing weekly slot, most of them from outside HVAC.
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Outdoor Reset & ECM Pumps
Outdoor reset pays back quickly for the life of the boiler — if the technician installs it correctly and teaches the homeowner to use it.
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Why do we have Sizing Limits?
Code sizing limits treated as a nuisance, and why a load calculation run after installation renders the whole process useless.
Read article arrow_forwardTXV Hunting Season
Early-season maintenance in cold mornings and R-410A valves that hunt — what to expect long before the units are needed in July.
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Diagnosing Improper Fixed Orifice Sizes
A cut-and-dry procedure for identifying the wrong fixed orifice, and the case for field-installing a TXV instead.
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No Bubbles, No Troubles!
The old sight-glass adage, and why a clear glass does not tell you the TXV has the subcooled liquid it needs.
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Site Survey: Area-Weighted Average R-Value
Attic insulation is hard to pin down on a quick sales call. The worksheet that turns what you saw into an area-weighted average R-value.
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New England: HRV or ERV?
HRV or ERV in a tight New England home: the freezing issue, the latent load, and choosing a balanced system you can control.
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Duct Gains: Why do we hate R-8?
Duct leakage gets tested; duct insulation gets a checkbox. The simple math for what poorly installed R-8 actually costs.
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Over-sized Equipment No More!
Regional standards, code-required load calculations and tighter homes still have not stopped gross oversizing. Why four and five ton systems should be variable speed.
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The #1 Item Missing from High Efficient HVAC Installations
Nobody plugs a new television straight into the wall socket. The protection routinely left off high-efficiency equipment.
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Sizing Humidifiers & Ancillary Dehumidifiers
Whole-house dehumidifiers are not sized by square footage. The Manual J block load procedure most technicians have never been shown.
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Enhancing Customer Service in HVAC Sales
Practical strategies for turning routine HVAC service into the memorable experiences that produce repeat customers.
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Why Your Golf Skills Are Your Secret Sales Weapon
What lining up a tee shot has in common with selling a comfort system — considerably more than it sounds.
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HVAC: Become a Master in 5 Years!
Gladwell’s ten thousand hours applied to the trade — the argument that HVAC mastery is a five-year proposition.
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A Successful Technician
A ballplayer succeeds batting .300; a technician diagnosing correctly a third of the time does not. What actually separates a good one.
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Perception: The Service Technician
The pride a service technician once took in representing the company, and an honest look at what changed.
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4 Things a Quality Contractor Would Not Say
Four lines that should raise a homeowner’s suspicion, starting with the discount that expires the moment the salesperson leaves.
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HVAC Industry: Who wins with High Warranties?
Warranty periods escalated until ‘limited lifetime’ became normal. A story about who actually collects when they do.
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HVAC & a Growth Mindset
A third-grade classroom wall and a Weldon Long sales class arrive at the same lesson about what capability actually is.
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Home Comfort, Satisfaction Guaranteed!
What L.L. Bean’s return policy buys in loyalty, and what an unconditional comfort guarantee would be worth to a contractor.
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Humidification: Forced-Air Systems
What to actually set the humidistat to. ASHRAE’s comfort zone, ACCA Manual RS, and the 35-45% range for forced air.
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Check the Flue?
The draft measurement on a natural draft appliance that complacency skips, and the indicators that should always trigger it.
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Non-Condensables? Are you sure?
A simple process for confirming non-condensables without burning hours and hundreds of dollars in virgin refrigerant.
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Energy Efficiency Ratio (EER)
Why EER is the more honest number for field energy savings than seasonal SEER, and the equation for calculating improvements.
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Diagnosing Bypass Air
Air that never crosses the evaporator cannot be cooled. Using delta T and superheat to confirm bypass before cutting into the plenum.
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Do you make this mistake on Maintenance?
Condenser coil cleaning is the task technicians skip most. Expanded performance data showing what skipping it does to capacity and EER.
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Completing a Total Leakage Duct Test
How the total leakage duct test is run, which towns enforce it, and the permit costs that quietly eat the job’s profit.
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Site Survey: Windows & SHGC
NFRC labels carry the u-value and SHGC your load calculation depends on. Guessing them swings the result thousands of Btu per hour.
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Top 5 Changes to ACCA Manual S
The five biggest updates in the Manual S rewrite, and how far the 1995 edition had fallen behind the equipment.
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How Low Should I Operate my Heat Pump?
Break-even COP math from ACCA Manual H for deciding when a dual-fuel application actually saves the homeowner money. Updated for Massachusetts.
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Design Static Pressure
Which external static pressure to design a duct system around, and why designing at the PSC motor’s maximum leaves you nowhere to go.
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Outdoor Design Temperatures
‘I have designed with these temperatures for decades’ does not satisfy an inspector. Where the correct outdoor design conditions come from.
Read article arrow_forwardStop Selling Low Profit Jobs!
A contractor thrilled to install ductless all day, and the margin math showing he was busiest on his worst work.
Read article arrow_forwardHVAC: A Fast Growing Career Opportunity
The skills gap in numbers, and the case for HVAC as a fast-growing, high-reward career worth recruiting into.
Read article arrow_forwardSelling with Rebates : The Simple Payback
The simple payback calculation that shows a homeowner exactly when the efficiency upgrade pays for itself.
Read article arrow_forwardHow can I compete and still do jobs right?
You cannot be the low bidder and still do the job right. How to make the quality difference legible to the customer.
Read article arrow_forward5 Things New Energy Efficiency HVAC Contractors Need to Know
Five things to get right before selling high-efficiency equipment in New England, starting with never selling on price.
Read article arrow_forward4 Reasons You Need a Quality Installation Manual
Four reasons an installation manual is what lets an owner stop being the only person who can do the work properly.
Read article arrow_forwardLabor Shortage in HVAC
The military recruits and trains eighteen-year-olds with zero experience. A blunt question for contractors who cannot find anyone.
Read article arrow_forwardThe Drop Light
Chris’s first published article, from 2012 and deliberately left unedited — why maintenance is the lever most technicians are never taught to value.
Read article arrow_forwardCouldn’t Leave HVAC When I Tried
Chris on the path out of the trade that pulled him back — and what it says about contractors who want more from this industry.
Read article arrow_forward3 Secrets to HVAC Sales Success
Most comfort advisors have never had formal sales training. The three habits that separate the ones who close from the ones who chase.
Read article arrow_forwardHigh CO Reading, Now What?
A high carbon monoxide reading does not automatically mean replacement. How to work the diagnosis before condemning equipment.
Read article arrow_forwardHeat Pumps & Record Snowfall
Snow buried condensers choke airflow and drive supplemental heat. What to tell homeowners before the nuisance calls start.
Read article arrow_forwardThe Enthalpy Method
Verify refrigerant charge without attaching gauges — the total capacity calculation and the tools it takes to do it right.
Read article arrow_forwardCorrectly Sizing a Capacitor
Stop installing whatever dual run capacitor is on the truck. The quick calculation that gets you the right size every time.
Read article arrow_forwardHow Do You Test a TXV?
A simple field test for a suspect thermostatic expansion valve using crushed ice and an accurate set of gauges.
Read article arrow_forwardReturn Air Locations
Where returns belong for heating-only, cooling-only, and combination systems, and why application drives the decision.
Read article arrow_forwardRules of Duct Design
The core ACCA Manual D rules for distributing conditioned air, collected in one place — the ones most techs never get taught.
Read article arrow_forwardCan You Trust Your Load Calc Software?
Default software settings quietly under-size loads. The values to check before you trust the number your load calc hands you.
Read article arrow_forwardClocking a Gas Meter
The firing rate calculation every technician, rater, and auditor should know — step by step, with the tips that keep it accurate.
Read article arrow_forwardCarbon Monoxide (CO): Weapon of Mass Destruction
Why carbon monoxide deserves more respect than the average service call gives it, and what technicians owe every homeowner.
Read article arrow_forwardTriple Evacuation vs. Deep Vacuum Method
Two evacuation strategies compared on what actually matters: removing moisture and non-condensables from the system.
Read article arrow_forwardThe Basics: Superheat
Superheat from the ground up — what it measures, how to read it off a PT chart, and what it tells you about the charge.
Read article arrow_forwardHeat Pump Equipment Selection
Selecting a heat pump against real Manual S expanded performance data instead of nominal tonnage.
Read article arrow_forwardHow to Pass Load Calc Requirements for a Permit
Exactly what building code officials expect to see with a load calculation submission — and how to stop failing permit applications.
Read article arrow_forwardUnderstanding Intermittent and Continuous Ventilation in ACCA Manual J
How Manual J treats intermittent versus continuous mechanical ventilation, and where load calculations go wrong when the two get mixed up.
Read article arrow_forwardGrow Your HVAC Business with Maintenance Contracts
Why a maintenance program is the most reliable growth lever in a contracting business, and how to build one customers renew.
Read article arrow_forwardWhat is a Good HVAC Sales Goal?
Setting a sales target that reflects real margin instead of vanity revenue, and what number a comfort advisor should actually be measured against.
Read article arrow_forwardWhy Homeowners Are Switching from Fossil Fuel Furnaces to Heat Pumps
What is actually driving homeowners off fossil fuel heating — and how contractors should be positioning heat pumps in the conversation.
Read article arrow_forwardFree: The 6 Mistakes Guide
The 6 mistakes costing contractors the job — plus weekly system design insights.
Want more technical depth?
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