At Bolton Construction & Service, we receive plenty of different questions related to things like air conditioning, boiler repairs, chiller replacements, furnace replacement, and other HVAC issues from homeowners and business owners in Raleigh, Durham, Apex, Cary, Clayton, Youngsville, NC, & surrounding areas. Here are several of the more frequently asked questions that we receive.
A single-stage AC has one speed: full blast. It cycles on, runs at 100% capacity until your thermostat is satisfied, then shuts off completely. A two-stage system has a low setting (around 65-70% capacity) and a high setting, so it can run longer at lower power on mild days. Variable-speed systems adjust continuously from about 25% to 100% capacity. The practical difference for homeowners: two-stage and variable-speed systems remove more humidity, maintain more even temperatures, run more quietly, and use less energy. They cost more upfront but typically pay for themselves through lower utility bills.
Your AC does remove some humidity as a byproduct of cooling — moisture condenses on the cold evaporator coil and drains away. However, in the area’s humid subtropical climate (especially during the muggy shoulder seasons of April-May and September-October), your AC alone may not keep indoor humidity below the ideal 40-50% range. If you notice condensation on windows, a musty smell, or the air feels clammy even when the AC is running, a whole-house dehumidifier integrated with your HVAC system is the most effective solution. It works independently of your AC, so it can control humidity even when cooling isn’t needed.
As of January 2025, all newly manufactured residential AC systems and heat pumps use R-454B refrigerant instead of R-410A. R-454B has 78% lower global warming potential, which is why the EPA mandated the switch under the AIM Act. If your current system uses R-410A, it will continue to work normally — R-410A is still available for repairs and recharges. You don’t need to replace your system. However, when it’s time for a new unit, your next AC installation will use R-454B. The new refrigerant requires slightly different handling and equipment, so make sure your technician is trained on A2L systems. Our team is already certified for R-454B installations and AC repairs on both refrigerant types.
No — this is one of the most common HVAC myths. Closing vents doesn’t reduce energy consumption. Your furnace and blower are sized for your entire home’s ductwork. When you close vents, it increases static pressure in the duct system, forcing the blower to work harder, which wastes energy and can damage components over time. Closed vents also create pressure imbalances that can cause air leaks in ductwork, increase heating costs in the rooms that are open, and even lead to condensation and mold in the closed-off rooms. Instead of closing vents, consider a professional HVAC assessment to optimize your system’s airflow, or ask about zone-controlled systems if some rooms consistently overheat while others stay cold.
A single-stage furnace operates at full capacity every time it fires. A two-stage furnace has a low-fire setting (around 60-65% capacity) and a high-fire setting, running on low most of the time and ramping up only on the coldest days. A modulating furnace adjusts its flame in small increments — typically between 40% and 100% — to precisely match your home’s heating demand. For our climate, a two-stage or modulating furnace provides noticeably better comfort: fewer temperature swings, quieter operation, and better humidity control during mild winter days. The energy savings range from 10-20% compared to single-stage models. Whether the upgrade is worth it depends on your home size, insulation quality, and how long you plan to stay. Our technicians can help you weigh the options during a furnace installation consultation.
Yes. A heat pump is a single system that provides both cooling in summer and heating in winter by reversing the direction of refrigerant flow. In cooling mode it works identically to an air conditioner; in heating mode it extracts heat from outdoor air and moves it inside. Modern heat pumps are highly effective in our climate, where winter temperatures rarely stay below freezing for extended periods. However, during extreme cold snaps (below 25-30°F), a heat pump’s output decreases and supplemental heat kicks in. Many homeowners choose a dual fuel system that pairs a heat pump with a gas furnace backup for the coldest nights — giving you the efficiency of a heat pump for 90% of the year and gas heat when you need it most. Learn more about your options with a heat pump installation consultation.
Your electricity bill will go up because the heat pump uses electricity to heat your home instead of gas. But your gas bill will drop to near zero (just the meter charge). The net result — your total energy cost — depends on local utility rates and the efficiency of both systems. In our area, a modern high-efficiency heat pump (HSPF2 of 9+) typically costs about the same or slightly less to operate annually than a mid-efficiency gas furnace (80% AFUE), considering current Duke Energy and Dominion gas rates. If you’re comparing to a high-efficiency gas furnace (95%+ AFUE), the gas furnace usually wins on operating cost by a small margin. The gap narrows if you qualify for heat pump tax credits or utility rebates.
Consider the “5,000 rule”: multiply the repair cost by the age of your system. If the result exceeds $5,000, replacement is usually the smarter financial choice. Other strong indicators include: your system is 15+ years old, repairs are becoming more frequent (two or more per year), energy bills keep rising despite maintenance, or your system uses R-22 refrigerant (phased out and increasingly expensive). A new high-efficiency system can cut energy consumption by 30-50% compared to a unit from the early 2000s. Federal tax credits and manufacturer rebates can offset a significant portion of the upfront cost. If you’re on the fence, schedule an HVAC inspection — we’ll assess your system’s condition honestly and help you weigh repair versus replacement options.
SEER / SEER2 (Seasonal Energy Efficiency Ratio) measures cooling efficiency. Higher is better — the federal minimum is 14.3 SEER2 for the Southeast region. Most mid-range units are 15-17 SEER2; premium units reach 20+. This is the rating that matters when comparing air conditioners.
AFUE (Annual Fuel Utilization Efficiency) measures furnace heating efficiency as a percentage — an 80% AFUE furnace converts 80% of gas to heat. High-efficiency models reach 95-98% AFUE. This matters when comparing furnaces.
HSPF / HSPF2 (Heating Seasonal Performance Factor) measures heat pump heating efficiency. The federal minimum is HSPF2 7.5; high-efficiency models reach 10+. This matters when comparing heat pumps.
In short: use SEER2 for cooling comparisons, AFUE for furnace comparisons, and HSPF2 for heat pump heating comparisons. Higher numbers always mean lower operating costs.
On a per-unit basis, ductless mini-splits are typically more efficient than central AC systems because they eliminate duct losses. The Department of Energy estimates that ductwork can lose 20-30% of conditioned air through leaks, poor connections, and heat transfer through uninsulated duct walls. Mini-splits deliver conditioned air directly into the room with no duct losses. However, if you need to cool your entire home, multiple mini-split heads (a multi-zone system) can approach or exceed the cost of a central AC system. Mini-splits excel in specific scenarios: additions, converted garages, sunrooms, or older homes without existing ductwork. For homes that already have good ductwork, central AC is usually more cost-effective to install for whole-home cooling. Learn about your options with a mini-split installation consultation.
Yes — this is exactly what ductless mini-splits were designed for. The indoor unit mounts on a wall (or ceiling), and a small conduit (about 3 inches in diameter) connects it to the outdoor unit through an exterior wall. No bulky ductwork, no major construction. Common applications in area homes include: finished attics and basements, garage conversions, sunrooms, home offices, and historic homes where cutting duct chases would damage original architecture. A single-zone mini-split system can heat and cool one room independently from your central system, giving you precise temperature control where you need it.
The standard wall-mounted indoor unit is about 32 inches wide, 12 inches tall, and 8 inches deep — roughly the size of a small shelf. It’s mounted high on the wall near the ceiling. Modern units from brands like Trane, Daikin, Mitsubishi, and Carrier have sleek designs that blend in reasonably well, but they are visible.
If aesthetics are a priority, there are alternatives: ceiling cassette units mount flush in the ceiling with only a small grille visible, floor-standing units sit at baseboard level, and slim duct units can be concealed in a small soffit or closet. These options cost more and require more installation work, but they’re nearly invisible. Discuss the options with our team during your mini-split installation consultation.
Any fuel-burning appliance — gas furnaces, gas water heaters, gas dryers — can produce carbon monoxide (CO) if they malfunction. The primary risk in HVAC systems is a cracked heat exchanger in a gas furnace, which can leak combustion gases (including CO) into your home’s air supply. Warning signs include: persistent headaches or flu-like symptoms that improve when you leave the house, a yellow or flickering pilot light (instead of steady blue), soot or scorch marks around your furnace, and excess condensation on windows near the furnace. Every home with gas appliances should have CO detectors on each level. For peace of mind, schedule an air quality inspection or annual furnace maintenance — our technicians specifically test for heat exchanger integrity and CO levels.
The EPA and ASHRAE recommend maintaining indoor relative humidity between 30% and 50%, with 40% to 45% being the sweet spot for comfort and health. In our area, the challenge shifts with the seasons:
Summer (May-September): Outdoor humidity often exceeds 70-80%. Your AC removes some moisture, but a whole-house dehumidifier may be needed to stay below 50% — especially during mild, humid days when the AC doesn’t run long enough to dehumidify adequately.
Winter (December-February): Heated indoor air can drop below 30% humidity, causing dry skin, static electricity, cracked woodwork, and increased respiratory infections. A whole-house humidifier integrated with your furnace adds moisture automatically to maintain comfort.
Absolutely. Leaky ductwork running through attics, crawl spaces, and wall cavities can pull in dust, insulation fibers, mold spores, and even pest droppings — then distribute them through every room in your home. Even well-sealed ducts accumulate dust, pollen, and allergens over time, especially during Raleigh’s heavy pollen season (March-May). If you or family members notice allergy symptoms that worsen when the HVAC runs, visible dust blowing from vents, or musty odors when the system starts, your ductwork may need attention. Professional duct sealing eliminates leaks that pull in contaminants, and duct cleaning removes accumulated buildup. An air quality inspection can identify whether your ducts are contributing to your symptoms.
MERV (Minimum Efficiency Reporting Value) rates how effectively an air filter captures particles on a scale of 1-20. Higher ratings catch smaller particles. For residential HVAC systems, the sweet spot is typically MERV 11-13.
MERV 8: Catches dust, pollen, and lint. The bare minimum for residential systems. Adequate if nobody in the house has allergies or respiratory issues.
MERV 11-13: Catches everything MERV 8 does plus mold spores, pet dander, fine dust, and some bacteria. Recommended for most area homes, especially during pollen season. This is what we install for our maintenance plan customers.
MERV 14+: Hospital-grade filtration. Catches very fine particles but can restrict airflow in residential systems not designed for it. Using too high a MERV rating can strain your blower motor and reduce efficiency; always check your system’s specifications or ask your technician. For advanced filtration without airflow restriction, consider a whole-house air purifier installed in your ductwork.
Standard 1-inch filters should be replaced every 30-90 days, depending on conditions. Homes with pets, smokers, or allergy sufferers should lean toward the 30-day end. Thicker media filters (4-5 inches) typically last 6-12 months. In our area, seasonal factors matter: during the March-May pollen season and peak summer usage (June-August), check your filter monthly. A dirty filter forces your system to work harder, reduces airflow, increases energy consumption by up to 15%, and can lead to frozen evaporator coils or compressor strain. Regular filter changes are the single most impactful thing homeowners can do between professional HVAC maintenance visits. Our Maintenance members receive filter reminders and priority scheduling.
A diagnostic service call in our area typically runs $75-$150 for the visit and diagnosis. This covers the technician’s travel time, initial inspection, and assessment of the problem. Repair costs vary widely depending on the issue: a capacitor replacement might be $150-$300 total, a blower motor $400-$700, a compressor $1,500-$2,500, and a heat exchanger $1,500-$3,000. For routine tune-ups (non-emergency preventive maintenance), expect $75-$200 per unit. Maintenance plan members typically receive discounted rates on both tune-ups and repairs, plus priority scheduling during peak season.
For most homeowners, yes — especially if your system is more than a few years old. A maintenance plan typically includes two professional tune-ups per year (spring for AC, fall for heating), priority scheduling during peak season, and discounted repair rates. Many plans also include no overtime charges for emergency calls. The financial case: a single emergency repair during a July heatwave can easily cost $300-$500 more than the same repair scheduled during a slow period, between the overtime fees and emergency dispatch charges. Regular maintenance also extends equipment lifespan by 3-5 years and reduces the likelihood of breakdowns by catching small issues before they escalate. Our maintenance packages are designed specifically for Raleigh homeowners who want to protect their investment without worrying about surprise costs.
There are several things homeowners can do to keep their HVAC system running well between annual tuneups:
Monthly: Check and replace your air filter (the single most impactful DIY task). Keep supply and return vents clear of furniture, rugs, and curtains.
Seasonally: Clear debris (leaves, grass clippings, mulch) from around the outdoor unit — maintain at least 2 feet of clearance on all sides. Rinse the outdoor coil gently with a garden hose. Check your thermostat batteries and settings when switching between heating and cooling seasons.
Annually: Visually inspect exposed ductwork in your attic or crawl space for obvious gaps or disconnections. Test your CO detectors. Clear your condensate drain line by flushing it with a cup of white vinegar (prevents clogs and water damage).
Leave the technical work — refrigerant checks, electrical testing, combustion analysis, and blower calibration — to a professional during your annual scheduled tune-up.
Call immediately (true emergencies): You smell gas or rotten eggs near your furnace (leave the house first, then call). You hear hissing from a gas line. You see sparks, smoke, or a burning smell from your HVAC equipment. Your system has completely failed during extreme heat (above 95°F) or cold (below 25°F), especially with children, the elderly, or medically vulnerable household members.
Can wait for regular scheduling: Uneven temperatures between rooms. Minor or intermittent noises. Gradually rising energy bills. One zone is not reaching the set temperature. A system that’s working but not as well as it used to.
Our technicians provide emergency AC service and emergency heating service 24 hours a day, 7 days a week. Call 919-851-1600 any time — we’ll help you determine whether your situation needs immediate attention or can be safely scheduled for the next available appointment.
Yes, typically. Emergency and after-hours service calls often include additional fees compared to standard business-hours appointments. This can include overtime labor rates (usually 1.5x the standard rate), after-hours dispatch charges, and priority scheduling premiums.
That said, some HVAC companies — including those with maintenance plans — waive overtime charges for plan members. If you’re on a maintenance plan, check your agreement for emergency service terms before assuming you’ll pay extra. For non-emergency issues discovered in the evening or on the weekend, it’s usually more cost-effective to schedule a regular appointment for the next business day rather than requesting same-day emergency service.
This is a true emergency — follow these steps in order:
After the gas company has cleared the home and shut off the supply if needed, call us for emergency furnace service to inspect, diagnose, and repair the issue before you resume using your heating system. Gas leaks can originate from loose connections, cracked heat exchangers, or faulty gas valves — all of which require professional HVAC repair.
Response times vary depending on the time of day, season, and current demand. During business hours in the off-season, same-day service is typically available — often within a few hours of your call. During peak summer and winter seasons, especially on weekends and evenings, response times may be longer due to high call volume.
As a general guide: for true safety emergencies (gas leaks, electrical hazards, CO detector alarms), technicians prioritize these calls and aim for the fastest possible response. For comfort emergencies (complete system failure during extreme weather), most calls are addressed within 2-6 hours during business hours or by the next morning for late-night calls.
Our Maintenance members receive priority scheduling, which moves them to the front of the queue. Call 919-861-1500 for emergency service — our dispatcher will give you an estimated arrival time based on current availability.
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Air Conditioning