Guides

Heating, Cooling & Water Heating guides

Heat pumps, mini splits, furnaces, air conditioning and water heaters: sizing, running cost, and what to buy.

guides: 94; guides
subtopics: 7; subtopics

0131 guides

Heat Pumps

10kW Heat Strip Breaker Size: Amps, Wire and a 5–20 kW Chart

A 10 kW heat strip draws 41.7 A at 240 V. As a continuous load it's sized at 125%, which lands on a 60 A breaker. Kits over 48 A, such as 15 and 20 kW, are split into two circuits, and the air handler's nameplate always has the final word.

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Best Heat Pump Brands: How the Manufacturers Actually Differ

Heat pump brands differ less than the marketing implies: several of the biggest names are the same equipment under different badges, and the industry's own performance data is published in a neutral directory anyone can search. What genuinely separates brands is distribution, parts availability and warranty structure.

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Heat Pump Electricity Usage: How Much Does One Actually Use?

A heat pump uses meaningful electricity because it is doing the heating, but it uses roughly a third of what electric resistance heat would, since it moves heat rather than making it. The bill shock people report usually comes from backup strip heat running, not from the heat pump itself.

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Do Heat Pumps Work in Cold Weather?

The old 'heat pumps don't work when it's cold' line is outdated. Here's how modern cold-climate heat pumps actually perform in winter, and what backup heat is for.

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Ductless vs Central Heat Pump: Which Is Right for You?

A ductless mini split mounts indoor heads on walls or ceilings and needs no ductwork, making it the retrofit answer for homes with baseboards, boilers or window units. A central heat pump uses existing ducts for even, hidden whole-home conditioning, and having sound ducts is what decides between them.

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Geothermal vs Air Source Heat Pumps

A geothermal heat pump exchanges heat with the ground at a stable 50–60°F, giving higher and steadier efficiency than an air-source unit that must work against outdoor air temperature. It is the better machine; whether it is the better purchase depends almost entirely on what the loop field costs at your site.

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Heat Pump Defrost Cycle: Why It Steams and When to Worry

A defrost cycle reverses the heat pump for a few minutes to melt frost off the outdoor coil, which is why steam pours off the unit and the air briefly blows cool. That is correct operation. An outdoor unit encased in ice that never clears is a defrost control or sensor fault.

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Heat Pump Installation Cost: What Drives the Price

Heat pump installation cost is driven far more by the house than the equipment: ducted versus ductless, whether a cold-climate model is needed, what backup heat is proposed, and whether the electrical service can take it. Ask specifically about backup heat: strip heat is cheap to fit and expensive to run.

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Heat Pump Maintenance: What Matters and What Doesn't

Heat pump maintenance comes down to two things you do yourself: change or clean the filter every 1–3 months, and keep the outdoor coil clear of leaves, grass and snow. A professional service once a year checks refrigerant charge, electrical connections and coil condition; most of what is sold beyond that is optional.

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Heat Pump Not Heating? Causes and Fixes

A heat pump not heating is often behaving normally: air from a heat pump is cooler than furnace air, and a defrost cycle briefly blows cool by design. Genuine faults are a stuck reversing valve, low refrigerant, backup heat failing to engage, or an outdoor unit iced over and not clearing.

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What Is a Heat Pump? How It Works, and the Real Pros and Cons

A heat pump is a single system that both heats and cools by moving heat rather than generating it, pulling warmth from outdoor air in winter and pushing it back out in summer. That is why it delivers 2.5 to 4 units of heat per unit of electricity, where a furnace tops out near 1.

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Heat Pump Refrigerants Explained: R-410A, R-454B and R-32

New residential equipment has moved to low-GWP A2L refrigerants such as R-454B and R-32, replacing R-410A. An existing R-410A system is not obsolete, but service economics shift as supply tightens, and A2L refrigerants are mildly flammable, which changes handling and equipment standards.

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Heat Pump Sizing: What BTU Do You Need?

A rough starting point is 20–30 BTU per square foot depending on climate, but two identical-sized homes can differ by a full ton. Oversizing causes short cycling and poor dehumidification; undersizing leaves you on backup heat. The real number comes from an ACCA Manual J load calculation.

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Heat Pump Thermostat Settings: Why Setbacks Can Cost You Money

With a furnace, turning it down at night saves money. With a heat pump and strip backup, it can do the opposite, and the reason is worth understanding.

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Heat Pump vs Electric Resistance Heat: Which Costs Less?

Electric resistance heat has a COP of 1.0; a modern heat pump runs at a seasonal COP around 2.5–3.5, so it delivers the same heat for roughly a third of the electricity. Resistance heat still wins on install cost, in rarely used rooms, and where the electrical service cannot take a heat pump.

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Heat Pump vs Furnace: Which Is Better for Your Home?

A heat pump moves heat at 250–400% efficiency and cools in summer too; a gas furnace burns fuel and tops out near 100% efficiency, heating only. Which costs less to run depends entirely on your local electricity-to-gas price ratio, and a dual-fuel setup keeping the furnace as cold-weather backup often beats either alone.

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How Does a Heat Pump Work?

A heat pump works by moving heat rather than making it: refrigerant evaporates and absorbs heat outdoors, a compressor concentrates it, and it condenses indoors to release that heat. A reversing valve swaps the two coils to run the cycle backwards for cooling. Because it moves heat, it delivers 2.5–4 units of heat per unit of electricity.

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How Long Does a Heat Pump Last?

An air-source heat pump lasts 15–20 years, shorter than a furnace because it runs year-round rather than seasonally; geothermal loop fields last far longer, often 50+ years. Maintenance, correct sizing and coastal salt exposure move that range more than brand does.

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Best Heat Pumps: How to Choose the Right System for Your Home

The best heat pump for a home is decided by four things in order: the distribution you already have (ducts, radiators, or none), whether you need cold-climate capacity, correct sizing from a Manual J load calculation, and only then the efficiency ratings on the sticker.

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Mini Split Cost: Equipment, Install and Price Drivers

Mini split cost splits into equipment and labor, and the number that moves it most is the head count, not the tonnage. Most homes are quoted more indoor heads than they need, and each one adds equipment, a line set, and labor.

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Why an Oversized HVAC System Is Worse Than an Undersized One

An oversized system reaches setpoint quickly and does everything else badly: short runs never dehumidify, so the room reads cool and feels clammy, temperatures swing, air distributes unevenly, and the compressor wears from repeated starts. An ACCA Manual J calculation is what prevents it.

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SEER2, EER2 and HSPF2 Explained

SEER2 rates seasonal cooling efficiency, EER2 rates it at a fixed hot condition, and HSPF2 rates seasonal heating. The DOE updated the test procedures in January 2023 to use higher external static pressure, which is why SEER2 numbers read lower than the old SEER for the same equipment.

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Single Zone vs Multi Zone Mini Split

A multi-zone mini split runs several indoor heads from one outdoor unit, which sounds efficient but means the compressor must modulate down for a single small load, and one failure takes out every zone. Separate single-zone systems often run better at part load and are far cheaper to repair.

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Variable Speed vs Single Stage Heat Pumps

A single-stage compressor runs at full output or not at all; a variable-speed inverter compressor modulates continuously, which is why it holds capacity better in cold weather, runs quieter, dehumidifies more and avoids the temperature swing of on-off cycling.

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What Is a Mini Split? How Ductless Heat Pumps Work

A mini split is a ductless heat pump: an outdoor condenser connected by a small refrigerant line set to one or more indoor heads mounted on walls or ceilings. It heats and cools without ducts, which makes it the standard retrofit for homes with baseboards, boilers or window units, and each head is independently controlled.

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Cold Climate Heat Pumps: How They Differ and When You Need One

Every heat pump loses capacity in the cold. A cold-climate model loses less of it, which is what decides how big your backup heater has to be.

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Do Heat Pumps Need Ductwork?

No ducts is not a barrier to a heat pump. It's a choice between three approaches, and the cheapest one is often not the obvious one.

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Dual Fuel Heat Pump Systems: How Hybrid Heating Works

The heat pump runs when it's efficient, the furnace runs when it isn't. No strip heat, no service upgrade, and usually the cheapest path in a home that already has a furnace.

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Heat Pump Backup Heat Explained

The strip heater behind your heat pump is three times more expensive to run and often the largest electrical load in the house. Sizing it correctly is the whole game.

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Heat Pump Noise Levels: What's Normal and What Isn't

The rating on the box is measured under laboratory conditions. Where you put the unit changes what you actually hear far more than the spec does.

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Heat Pump vs Air Conditioner: What's the Difference?

A heat pump and an AC cool your home the exact same way: the only real difference is that a heat pump can also heat. Here's when that's worth it.

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029 guides

Furnaces, Boilers & Other Heating

What Size Furnace Do I Need? BTU Sizing by Home and Climate

A rough starting point is 30–60 BTU per square foot depending on climate zone, so a 2,000 sq ft home lands somewhere between 60,000 and 120,000 BTU. That range is too wide to buy from, because climate, insulation, air leakage and window area move the real number far more than floor area does: the correct figure comes from an ACCA Manual J calculation.

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AFUE and Furnace Efficiency Explained

AFUE is the fraction of fuel energy a furnace turns into useful heat over a season: 80% for a mid-efficiency unit, 90–98% for a condensing one. The jump past 90% changes the venting, not just the bill: condensing furnaces exhaust cool wet flue gas through PVC and need a condensate drain.

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Electric Baseboard Heating Explained

Electric baseboard heat has a COP of 1.0 (one watt in, one watt of heat out), making it the cheapest electric heat to install and the most expensive to run. Size at roughly 10 W per square foot in a well-insulated room, on a dedicated 240 V circuit.

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Furnace Replacement Cost: What a New Furnace Costs Installed

Furnace replacement cost is driven far more by what surrounds the furnace than by the furnace itself: efficiency tier, whether the venting has to change, the condition of the existing ductwork, and how difficult the old unit is to get out.

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Furnace Not Heating? Causes and What to Check First

A furnace not heating splits into two very different problems: it will not start at all, or it starts and blows cold. The first points at power, thermostat or ignition; the second at a flame sensor, a limit switch, or a blower running without a call for heat.

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Furnace vs Boiler: What's the Difference?

A furnace heats air and distributes it through ducts; a boiler heats water and distributes it through radiators, baseboard or radiant floor. The practical consequence is cooling: a furnace shares its ducts with central air conditioning, while a boiler cannot deliver cooling at all.

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How Long Does a Furnace Last?

A gas furnace lasts 15–25 years, with 15–20 the usual range before efficiency and reliability decline. Regular filter changes and correct sizing extend it; short cycling from an oversized unit shortens it. A cracked heat exchanger ends the conversation at any age: that is a replacement, not a repair.

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Radiant Floor Heating Explained

Two different systems share the name: hydronic radiant, where warm water in tubing heats a whole house at low temperature, and electric mats, which warm a bathroom or kitchen floor but are too expensive to run as primary heat. Which one you mean changes every answer.

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Wood and Pellet Stove Heating Cost

Cordwood and pellets are sold by volume and weight rather than by heat, so compare them on cost per million BTU delivered. A cord of seasoned hardwood holds roughly 20 million BTU and a ton of pellets about 16.5 million. Then divide by appliance efficiency, typically 70–80% for EPA-certified units.

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0314 guides

Air Conditioning

AC Not Working? How to Diagnose It Before You Call

When an AC is not working, start with the four things you can check in five minutes: the thermostat mode and batteries, the breaker, the air filter, and whether the outdoor unit is running. A frozen indoor coil, the next most common cause, is usually a symptom of one of them.

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AC Short Cycling: Causes and Fixes

Short cycling is an air conditioner starting and stopping in runs of a few minutes instead of 10–20. The causes are a dirty filter, low refrigerant, a frozen or dirty coil, a bad thermostat location, or an oversized system, which is the one people miss because it looks like good performance.

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Air Conditioner Maintenance Checklist

Three habits prevent most summer breakdowns: change the filter every 1–3 months, keep the outdoor condenser coil clear of grass and debris with 2 feet of clearance, and keep the condensate drain running. An annual professional service checks refrigerant charge and electrical connections.

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Central Air Conditioning Installation Cost

Central AC installation cost is driven by whether you replace the condenser alone, a matched system, or add ductwork. If you are replacing an air conditioner, price a heat pump alongside it: the hardware overlaps almost entirely, and one of them also heats.

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How Long Does an HVAC System Last? AC, Furnace, Heat Pump

Central air conditioners typically last 15–20 years, furnaces 15–25, and heat pumps 12–18 because they run year-round rather than seasonally. Maintenance, correct sizing and climate move those numbers more than brand does.

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How to Cool a House Without Air Conditioning

The largest lever is stopping sun reaching the glass, because shading a window before the heat arrives beats removing that heat afterwards, and exterior shade outperforms interior blinds substantially. After that: close up by day and ventilate at night, and use fans only in occupied rooms.

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How to Cool a Hot Upstairs Room

Heat rises, the attic bakes, and the ducts serving upstairs are the longest in the house. Three problems, and the fixes are cheaper than a bigger AC.

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Portable Air Conditioners: Why Single-Hose Units Disappoint

A single-hose portable air conditioner exhausts conditioned room air outside, creating negative pressure that pulls hot outdoor air in through every gap to replace it, which is why it underperforms a window unit of the same rating. Compare on the DOE/SACC rating, not the older ASHRAE figure.

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Refrigerant Leak Signs in a Heat Pump or AC

Refrigerant is not consumed, so a system that is low has a leak. The signs are ice on the line or coil, weak cooling with long run times, hissing or bubbling, and oily residue at a joint. Topping up without finding the leak is a subscription, and venting refrigerant is illegal under EPA Section 608.

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What Size Air Conditioner Do I Need?

A common starting estimate is 20 BTU per square foot, but that ignores the six things that actually set cooling load: climate, insulation, air leakage, window area and orientation, ceiling height, and occupancy. The correct number comes from an ACCA Manual J calculation, not a rule of thumb.

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Window AC Sizing Guide

Start at roughly 20 BTU per square foot, then adjust: add 10% for a very sunny room, subtract 10% for a shaded one, add 600 BTU per additional occupant, and add 4,000 BTU for a kitchen. Oversizing is the common error: it cools fast, never dehumidifies, and leaves the room clammy.

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Central AC vs Mini Split: Which Suits Your House?

If you already have sound ducts, use them. If you don't, ductless usually wins on cost and efficiency, and there's a third option most people aren't offered.

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Evaporative Cooler vs Air Conditioner

In dry desert air a swamp cooler is genuinely excellent and costs a fraction to run. In humid air it's a fan that makes the room damp.

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Mini Split vs Window AC: Which Makes Sense for One Room?

A window unit is cheap and adequate. A mini split is expensive, quiet, and also heats. Which wins depends almost entirely on how many hours it runs.

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0415 guides

Water Heating

Does a Gas Water Heater Need Electricity: Which Types Work in an Outage

A standing-pilot tank powers its own gas valve from the pilot flame and keeps making hot water in a blackout. Anything with a vent fan, electronic ignition or a control board, including virtually every gas tankless, stops when the power does.

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Does a Tankless Water Heater Need Electricity: Gas and Electric Models

A gas tankless water heater runs on gas but can't operate without a 120 V supply for its control board, igniter, combustion fan and freeze protection, so the taps run cold in an outage. An electric tankless unit is the opposite problem: it needs several 240 V circuits and a service big enough to feed them.

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Tankless vs Tank Water Heater

A tankless water heater heats on demand and never runs out, but it can only heat so fast: output is limited by flow rate and incoming water temperature. A tank stores 40–80 gallons and delivers it all at once, then needs recovery time. Whole-house electric tankless commonly needs 100–150 amps, which rules it out for most homes.

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Water Heater Leaking? What to Do First

Shut off power or gas and the cold supply first, then find the source. A dripping T&P valve usually means excess pressure from thermal expansion, not a bad valve; never plug it. A leak from the tank body itself is terminal: a rusted tank cannot be repaired.

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Best Electric Water Heater: Heat Pump, Tank or Tankless

The biggest decision in an electric water heater is not the brand, it is the type. A heat pump water heater uses roughly a third of the electricity of a standard electric tank for the same hot water, which makes the running-cost gap between types far larger than any gap between brands.

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Heat Pump Water Heater: How It Works, Cost, and Whether It Fits

A heat pump water heater moves heat out of the surrounding air into the tank instead of generating it with an element, so it uses roughly a third of the electricity of a standard electric water heater. The trade-offs: it needs air volume around it, it cools the space it sits in, and it recovers more slowly.

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Hot Water Recirculating Pump: Is It Worth It?

A hot water recirculating pump keeps hot water moving through the supply line so it arrives at the tap in seconds instead of after a long run of cold. It saves water and waiting; it costs electricity and some standby heat, which is why timer or on-demand control decides whether it pays.

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How Long Does a Water Heater Last? Lifespan & Signs to Replace

A conventional tank water heater lasts 8–12 years, a tankless unit 15–20, and a heat pump water heater 10–15. Water hardness, an unmaintained anode rod and skipped flushing are what shorten it. Rust-coloured water, a rumbling tank or any leak from the tank body itself means replacement, not repair.

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How to Flush a Water Heater (Step-by-Step): Tank & Tankless

Flushing a water heater means draining the tank through the bottom valve to clear sediment, and it takes about an hour. Do it every 6–12 months in hard water, every 1–2 years in soft. Sediment insulates the burner on a gas heater and buries the lower element on an electric one, which is what the rumbling noise is.

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Anode Rod: What It Does and When to Replace It

An anode rod is a sacrificial metal rod inside a water heater that corrodes in place of the steel tank. Once it is consumed the tank starts rusting, which is why replacing a $30 rod every few years is the single cheapest way to double a water heater’s life.

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Water Heater Installation Cost: What Drives the Price

Replacing like with like is a short job. Changing type or fuel brings venting, electrical, or gas work, and code items the old install predates.

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Water Heater Not Heating? Causes and What to Check

A water heater not heating usually comes down to a handful of causes: on electric, a tripped breaker, a tripped high-limit reset, or a failed heating element; on gas, a pilot or igniter fault, a failed thermocouple, or a gas supply problem. Lukewarm water points to a different set of causes than no hot water at all.

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What Temperature Should a Water Heater Be Set To?

120°F is the standard residential recommendation: hot enough for normal use, low enough that a child or older adult is not scalded in seconds. Storing at 140°F suppresses Legionella but scalds fast, and the resolution is a thermostatic mixing valve delivering 120°F from a hotter tank.

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What Size Water Heater Do I Need?

Tank gallons is the number on the box; first-hour rating is the number that decides whether you run out. Estimate your peak-hour demand (15 gallons per shower, 8 for a dishwasher) and match the first-hour rating to it. A 40–50 gallon tank suits most households of two to four.

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Gas vs Electric Water Heater

Gas recovers faster and usually costs less to run than resistance electric. But the real comparison now is gas versus a heat pump water heater.

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058 guides

Insulation & Air Sealing

Are New Windows Worth It for Energy Savings?

New windows are among the slowest-paying energy upgrades, often 20+ years on energy savings alone, because windows are a small share of a home’s heat loss compared with the attic and air leakage. Buy them for comfort, condensation, noise or rot, and air-seal and insulate first.

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How Much Does Attic Insulation Cost?

Attic insulation cost is driven by area, target R-value and material, and most US attics need R-49 to R-60 depending on climate zone. The line items that inflate a quote are removing old or contaminated insulation, poor attic access, and the air sealing that should be done first: sealing the ceiling plane before adding depth.

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What R-Value Insulation Does Your Attic Need?

R-value measures resistance to heat flow, and DOE recommends R-49 to R-60 in most US attics; R-38 in the warmest zones. Most homes built before the 1990s have R-19 or less, and the code minimum your jurisdiction adopted is separate from the recommendation.

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Basement and Crawl Space Insulation Done Right

Insulate the walls of a conditioned basement, not the ceiling, and use rigid or closed-cell foam rather than fiberglass: batts against a foundation wall trap moisture and grow mould. The rim joist is the highest-value single job, and any crawl space needs a ground vapour barrier first.

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How to Air Seal a House (And Why It Comes Before Insulation)

Air sealing stops conditioned air leaving; insulation only slows heat moving through. Do sealing first (top plates, penetrations, the attic hatch and recessed lights) because insulating a leaky ceiling plane is insulating a sieve. IECC R402.4 sets the envelope leakage requirement.

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Insulation Types Compared: Fibreglass, Cellulose and Foam

Fiberglass batts are cheapest and suit open accessible cavities; blown cellulose fills irregular spaces and existing walls; closed-cell spray foam air-seals and insulates at the highest R per inch; mineral wool adds fire and sound performance. The cavity decides more than the R-value does.

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Wall Insulation for Existing Homes: Your Retrofit Options

With walls closed up the options are dense-pack cellulose or foam injected through drilled holes, or exterior rigid foam applied when the siding comes off. Drill-and-fill is the practical retrofit; exterior foam is better but only makes sense during a re-siding project.

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Weatherstripping and Draft Proofing: The Cheap Fixes That Work

Weatherstripping seals moving gaps (doors, operable windows, attic hatches) while caulk seals fixed joints. Match the material to the gap: V-strip for door jambs, foam tape for compression, door sweeps at thresholds. It is an afternoon of work and among the cheapest comfort gains available.

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069 guides

Ventilation & Air Quality

Attic Fan Installation: Roof, Gable and Solar, Step by Step

Attic fan installation is a half-day job for a roof or gable mount, but the part that decides whether it works is done before the fan goes in: adding enough soffit intake to feed it. A fan installed over blocked soffits pulls conditioned air out of the house instead of outdoor air through the attic.

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Attic Fan: How It Works and Whether It Helps

An attic fan is a powered exhaust fan that pushes hot air out of the attic, usually thermostat-controlled around 100–110°F. It only helps when the attic has enough intake venting to feed it; starved of intake air, it pulls conditioned air out of the house through ceiling leaks instead.

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Bathroom Exhaust Fan Sizing and Installation

Size a bathroom fan at roughly 1 CFM per square foot for rooms under 100 sq ft, with 50 CFM the practical minimum. Most fans underperform because of the duct, not the fan (undersized, flexible and too long), and venting into the attic instead of outside is both a code violation and a mould source.

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Do Air Purifiers Actually Work?

Air purifiers work for what they are designed to capture: a true HEPA filter removes at least 99.97% of particles at 0.3 microns, including dust, pollen, smoke and dander. They do nothing for CO2 or most gases, sizing to the room (CADR) decides whether one helps at all, and ozone-generating models can make air quality worse.

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Home Humidity Control: Why Cold and Clammy Happens

Indoor relative humidity should sit between 30% and 50%. Above that, 72°F feels clammy and lowering the thermostat makes it colder without making it comfortable; below it, static and dry air. Humidity, not temperature, is usually what is wrong when a room at the right temperature feels wrong.

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HRV vs ERV: Which Ventilator Does Your House Need?

Both an HRV and an ERV recover heat from outgoing stale air, but only an ERV also transfers moisture. That single difference decides the choice: an ERV suits humid climates and dry winters by moderating indoor humidity, an HRV suits cold climates where you want moisture expelled.

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HVAC Air Filters and MERV Ratings Explained

MERV rates filtration from 1 to 16 under ASHRAE 52.2; MERV 8–11 suits most residential systems and MERV 13 captures fine particles. Higher MERV restricts airflow, and past what your blower is designed for that restriction costs capacity, efficiency and equipment life.

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Whole House Fan: How It Works and How to Size One

A whole house fan mounts in the ceiling and pulls cool outdoor air in through open windows, exhausting hot indoor air into the attic. It uses a fraction of the power of air conditioning, but it only works when outdoor air is actually cooler, so it suits dry climates with cool nights and struggles in humid ones.

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Why Your House Feels Stuffy (And What Fixes It)

Stuffy usually means too little fresh air rather than too little airflow: a tight house accumulates moisture, CO2 and VOCs without mechanical ventilation. ASHRAE 62.2 sets the rate a dwelling should achieve, and an HRV or ERV is what delivers it without dumping heat.

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078 guides

Running Cost

Why Is My Electric Bill So High? 9 Common Causes

An electric bill spikes for one of three reasons: a rate change, a usage change, or something running that should not be. The usual culprits are electric resistance heat or heat pump strip heat in winter, air conditioning in summer, an aging water heater, and a well or sump pump cycling on a fault.

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Do Ceiling Fans Save Money?

A ceiling fan draws 15–90 watts, costing pennies an hour, and creates a wind-chill effect that makes a room feel 4°F cooler, but it cools people, not air. Running one in an empty room costs money and adds a small amount of motor heat, so switch it off when you leave.

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Ductwork Problems: Leakage, Sizing, and What Fixing Them Costs

You can buy the most efficient system available and still lose a large share of it in an attic. Ducts are where the money quietly goes.

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How to Estimate and Lower Your Electricity Bill

Estimate any appliance’s cost with watts × hours ÷ 1,000 × your rate per kWh. The US average home uses roughly 850–950 kWh a month, and space conditioning, water heating and the largest always-on loads account for most of it, which is where reductions actually show up.

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Heating Cost by Fuel Type: How to Compare Properly

Therms, gallons, kWh and cords are not comparable until you convert each to cost per million BTU delivered: fuel price divided by energy content, then divided by appliance efficiency. Natural gas at $1.20/therm in a 95% furnace is $12.63/MMBtu; electric resistance at 16¢/kWh is $46.88.

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How Much Does HVAC Cost to Run?

Four numbers give a usable estimate: output BTU/h ÷ 3,412 for kW of heat delivered, divided by COP for electrical input, times hours run, times your rate. A 40,000 BTU/h heat pump at COP 2.5 draws 4.7 kW: about 56 kWh over 12 hours, against 140 kWh for resistance heat.

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Do Smart Thermostats Actually Save Money?

Most of a smart thermostat’s saving comes from scheduled setbacks, which a plain programmable also does. The premium is worth it for irregular schedules, geofencing and utility demand-response programs. On a heat pump, look specifically for one that manages backup heat, or it can cost more than it saves.

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What Is a kWh? Kilowatt-Hours Explained Simply

A kilowatt-hour is 1,000 watts drawn for one hour, the unit your utility bills. Calculate it with watts × hours ÷ 1,000: a 1,500 W space heater running 4 hours uses 6 kWh. Watts measure the rate of use; kilowatt-hours measure the total, which is what you actually pay for.

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