Glossary

AFUE (Annual Fuel Utilization Efficiency)

The percentage of fuel energy that becomes usable heat over a full heating season for gas, propane, or oil furnaces. A 95% AFUE furnace turns 95 cents of every fuel dollar into heat; the other 5% goes up the flue. Modern condensing furnaces hit 95-98% AFUE. The minimum for new residential furnaces in Wisconsin is set by federal regulation and updated periodically.

See also: Heat pump vs furnace →

AHJ (Authority Having Jurisdiction)

The local building department empowered to enforce code and issue permits in your municipality. In our service area the AHJ is usually Walworth County, a specific town within the county, Waukesha County, a Waukesha municipality, Racine County, or a Racine municipality. The AHJ for an East Troy home is different from the AHJ for a Lake Geneva home.

See also: Permits & code compliance pillar →

Anode rod

A sacrificial metal rod inside a tank water heater that corrodes preferentially to the steel tank, extending tank life. Magnesium is standard; aluminum or aluminum-zinc anodes last longer in hard-water or iron-loaded supplies. Should be inspected every 3-4 years and replaced when more than 50% consumed.

See also: Annual maintenance schedule →

ATS (Automatic Transfer Switch)

The relay that disconnects your house from the utility grid and connects it to a backup generator within seconds of an outage detection. Required by code for standby generator installations. The ATS sits between the utility meter and the main panel (whole-house switching) or between the main panel and a critical-load subpanel (partial-house switching).

See also: Whole-house generator vs portable →

Backflow preventer

A valve assembly that prevents contaminated water from flowing back into the potable supply. Required at the building service connection in many jurisdictions and at certain fixtures (irrigation systems, boiler feeds, commercial connections). Wisconsin code requires annual testing of testable backflow assemblies.

BTU (British Thermal Unit)

The amount of energy required to raise one pound of water by one degree Fahrenheit. The standard unit for rating heating equipment capacity. A typical 2,400 sq ft home has a heat-loss design load somewhere around 60,000-90,000 BTU/hour depending on climate, insulation, and air-tightness. A small water heater is 30,000-40,000 BTU input; a tankless can be 180,000-199,000 BTU input.

COP (Coefficient of Performance)

The ratio of heating output to electrical input for a heat pump. A geothermal heat pump in heating mode often runs at COP 3.5-5.0 — meaning 3.5-5 units of heat for every 1 unit of electricity. By comparison, electric resistance heat is COP 1.0 and a 95% AFUE furnace is roughly COP 0.95.

See also: How geothermal works →

Drain camera (sewer camera)

A waterproof color camera on a fiber-optic push cable inserted into a drain or sewer line for inspection. Standard practice after any drain cleaning to confirm the line is clear and to identify cracks, offsets, or root intrusions that may need repair. O'Leary runs a camera after every hydro-jet job.

See also: What is hydro-jetting? →

Electrical service panel

The metal cabinet (usually in the basement, garage, or utility room) that distributes the utility power coming into your home into the branch circuits that feed each room. Houses the main disconnect breaker and individual circuit breakers. Common residential service sizes: 100A (older homes), 200A (modern standard), 320A or 400A (large homes with EV + heat pump + electric appliances).

See also: Panel upgrade permits →

Focus on Energy

Wisconsins statewide energy-efficiency program, funded by a surcharge on all utility bills in the state. Pays cash rebates for installing qualifying high-efficiency HVAC, water heaters, insulation, and other equipment. O'Leary is a registered Focus on Energy Trade Ally and handles every rebate application in-house.

See also: Focus on Energy rebate guide →

Geothermal (ground-source heat pump)

A heat pump that exchanges heat with a fluid loop buried in the earth (or in a pond) rather than with outdoor air. Because soil temperature stays around 50-55°F year-round in Wisconsin, the system operates at high efficiency even on the coldest nights. Highest installed cost; lowest operating cost; longest expected life.

See also: How geothermal works →

GFCI (Ground Fault Circuit Interrupter)

A safety device that monitors current balance between the hot and neutral conductors of a circuit. If imbalance is detected (suggesting current is leaking through someone to ground), the GFCI interrupts the circuit within milliseconds. Required by NEC in bathrooms, kitchens, garages, outdoors, basements, and around any water exposure including docks and piers.

See also: Dock and pier electrical →

Hard water (grains per gallon, gpg)

Water containing dissolved calcium and magnesium that leave scale on plumbing fixtures and reduce soap effectiveness. Measured in grains per gallon (gpg) of hardness. Walworth County wells typically test 10-25 gpg — well above the soft threshold of 1 gpg. Anything over 7 gpg is classified as very hard.

See also: What is a water softener? →

Heat pump (air-source)

An HVAC unit that transfers heat using a refrigerant cycle — moving heat from outdoor air into the house for heating, or out of the house for cooling. Modern cold-climate heat pumps operate effectively down to -13°F or lower. One appliance handles both heating and cooling, often qualifying for federal 25C and Focus on Energy incentives.

See also: Heat pump vs furnace →

Hydronic radiant heat

Heating delivered by warm water circulating through tubing or panels — radiant floor tubing, panel radiators, or baseboard. Common in lake-country new construction and in boiler-heated older homes. Pairs well with heat pumps, geothermal, and condensing boilers. Slow to respond to setpoint changes but extremely comfortable.

Hydro jetting

Drain or sewer cleaning using high-pressure water (2,000-4,000 PSI at 8-18 GPM) delivered through a specialized hose with forward and reverse nozzles. Scours the pipe wall back to its original diameter, unlike a cable snake which only punches a hole through the blockage.

See also: What is hydro-jetting? →

IGSHPA certification

Certification from the International Ground Source Heat Pump Association — the standards body for geothermal heat pump installation in North America. Certifies that the technician has completed formal training in ground-loop design, drilling/excavation specifications, refrigerant handling, and system commissioning. Kevin O'Leary holds IGSHPA certification.

See also: How geothermal works →

Iron filter

A whole-house filtration unit specifically engineered to remove iron and manganese from well water. Three common types: air-injection oxidation (best for moderate iron), greensand catalytic media (best for iron + manganese together), and chlorination + carbon (best for high iron or iron bacteria). Always installs upstream of the water softener.

See also: Why is my well water rusty? →

NEC (National Electrical Code)

The model code (NFPA 70) governing electrical installations in the United States. Wisconsin adopts the NEC with state-specific amendments. Article 555 covers marinas, docks, and piers; Article 680 covers pools, spas, and hot tubs; both are heavily safety-driven sections relevant to lake-country properties.

P-Trap

The U-shaped section of drain pipe under every sink, tub, and floor drain. Holds a small reservoir of water that blocks sewer gases from rising into the building. A dry trap (from a fixture that hasn't been used for months) is the most common source of sewer odors in vacation homes.

PEX (cross-linked polyethylene)

Flexible plastic tubing widely used for residential water supply since the 1990s. Resists freeze damage better than copper, costs less to install, doesn't corrode, and joins with crimp or expansion fittings. The dominant supply piping material in new Wisconsin construction.

Pressure regulator (PRV)

A valve installed on the building water supply that reduces incoming pressure to a safe range (typically 50-75 psi). Without one, high incoming pressure can damage fixtures, appliances, and the water heater. Wears out and needs replacement every 10-15 years.

R-410A / A2L refrigerants

Refrigerants used in modern residential AC and heat pump systems. R-410A replaced the phased-out R-22 in the 2010s. New systems are transitioning again to A2L low-GWP refrigerants under EPA regulations. R-22 systems are functional but expensive to service due to refrigerant scarcity.

Reverse osmosis (RO)

A water filtration method that forces water through a semi-permeable membrane, removing 95-99% of dissolved solids, salts, and many contaminants. Typically installed as a 4-5 stage point-of-use unit under the kitchen sink with a dedicated faucet. Best paired with a water softener upstream to extend membrane life.

See also: RO vs softener →

SEER2 / HSPF2

The current efficiency ratings for residential AC (SEER2) and heat pump heating (HSPF2), updated from SEER and HSPF in 2023 to use a more representative real-world test method. Higher numbers mean better efficiency. Federal minimums and the rebate-qualifying tiers update periodically — check the current Focus on Energy thresholds when planning a project.

Sump pump

An electric pump installed in a pit at the lowest point of the basement that automatically pumps groundwater away from the foundation. The first line of defense against basement flooding. Pair with a battery backup pump for outage protection — primary pumps fail without power, which is often exactly when you'll need them.

Tankless water heater

A water heater that heats water on demand as it passes through, rather than storing it in a tank. No standby loss; endless hot water for a single demand; limited flow rate for simultaneous demand. Requires annual descaling in hard-water areas. Lifespan 20+ years with proper maintenance.

See also: Tankless vs tank explained →

TDS (Total Dissolved Solids)

The aggregate amount of dissolved minerals, salts, and metals in water, measured in parts per million (ppm) or mg/L. A simple meter reads TDS in seconds. High TDS in well water typically indicates a mix of hardness, iron, and trace minerals — useful diagnostic data, but TDS alone doesn't tell you which specific mineral is causing your visible water issue.

Trenchless sewer repair

Sewer line repair methods that minimize excavation — pipe lining (a resin-impregnated sleeve cured inside the existing pipe) or pipe bursting (pulling a new pipe through the path of the old one while breaking the old one out). Lower yard disruption than open trenching; not appropriate for all conditions.

UV water disinfection

An inline water-treatment unit that exposes incoming water to ultraviolet light, killing bacteria, viruses, and protozoa. Used when a well tests positive for coliform or other microbiological contaminants. Requires annual lamp replacement and pre-filtration for effectiveness.

See also: Iron filter vs UV vs softener →

Variable-speed compressor / motor

An HVAC component that adjusts its speed continuously to match the home's current heating, cooling, or airflow load — rather than cycling fully on and off. Result: more even temperatures, better humidity control, quieter operation, and significantly lower operating cost than single-stage equipment.

Water hammer

The loud bang in plumbing when a fast-closing valve (washing machine, dishwasher, ice maker) stops flowing water suddenly, sending a shock wave back through the pipes. Long-term, this stress can break fittings. Fixed by adding water-hammer arrestors near the offending fixture.

Well pump

The pump that lifts water from a private well into the house. Submersible pumps sit at the bottom of the well casing; jet pumps sit in the basement and draw water up. Sized to deliver pressure plus flow against the wells static water level. Failure during a power outage requires either a backup generator or a manual hand pump.

Whole-house surge protector

A protective device installed at the electrical service panel that intercepts voltage spikes from lightning, utility switching, and other transients before they reach household electronics and appliances. Required by current NEC code on new and upgraded panels. Different from plug-in surge strips, which protect only what's plugged into them.