Frequently Asked Questions

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General HVAC Questions

HVAC is short for Heating, Ventilation, and Air Conditioning. These are the systems that regulate airflow, air exchange, temperature and heat transfer in your home or business. This requires professional training to install and safely maintain, just like the plumbing or electrical wiring in your house.

We recommend scheduling routine HVAC maintenance appointments seasonally, in the spring and fall. To make sure everything is functioning properly, safely and at it’s peak efficiency. This is really no different than your car. Routine maintenance and preventative measures will help get the most out of your investment.

Most standard air filters need to be replaced every 30 to 60 days, but if your home is exposed to high levels of allergens like pet hair or someone in your home has respiratory issues, you may need to change the filter more often. The higher end filter systems can last 6 months to a year based on air quality of the space. The filter not only helps the air you breathe, a good filter system will also protect your furnace blower from dust and debris.

Indoor Air Quality, or IAQ, measures the freshness, purity, temperature, and humidity of your home, making it the single most important measurement for the quality of the air you breathe. Damp or polluted air can have lasting effects on your health. We can offer many options to address these concerns. Such as; whole house Dehumidifiers, Humidifiers, ERV & HRV, UV lights, hospital grade filter systems, air scrubbers and Ionization.

HVAC systems can last a long time if regularly maintained. They can last 15-20 years. Some of units we have been servicing are approaching 30 plus years old, though that is rarer, they are also less efficient. A professionally, properly installed and well maintained HVAC system can save you money.


Furnaces can last 15 to 20 years, or more with proper maintenance. Ask our technicians during a furnace maintenance visit to evaluate both the age and maintenance records of your furnace for a specific recommendation. Keep in mind to look for the higher efficiency models that fits your budget. This will save on annual heating bills.

We can perform routine maintenance checks before the weather turns chilly so any small issues can be spotted before they become serious. The following are other complaints we often hear in the cooler months.
Need help lighting pilot light – House or rooms are too cold – Furnace not firing – Heater not keeping up with the cold – Heat pump not working – Thermostat broken – Hot air not blowing – Weird smell when furnace starts up – Vents not blowing warm air – Utility bills too expensive.

MERV is an acronym that stands for minimum efficiency reporting value. MERV is measurement scale (1-16) created by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) to rate the effectiveness of air filters. The higher the MERV,the more efficient the air filter is and the harder it is for your system to draw air through the system. We generally recommend between 7-11 MERV filters for most circumstances.

Most of the newer heaters no longer operate with pilot lights like they did in the past. If you need more help with your furnace or heater, we can answer your questions. We recommend yearly maintenance all heaters and furnaces to spot issues while they are small, so your heater doesn’t leave you cold in the dead of winter.

Where can I find information about energy efficiency tax rebates from city, state, and federal sources? We recommend visiting the State Energy Conservation Office which compiles resources to track down these rebates! Also be sure to check with your electrical utility as they sometimes offer rebate programs for installing energy-efficient air conditioning and heating systems. EnergyStar also has a website to search for rebates on EnergyStar-certified appliances


It’s hard for the average homeowner to know when to replace an Air Conditioner. But your HVAC technician can alert you when the cost of repairs is greater than the cost of replacing the system with one that saves you more money on your energy bill. If your utility costs are increasing or you notice your AC is no longer keeping your home cool, those are clear signs it’s time for an inspection and possibly a new AC system.

You can turn it off at the thermostat, and set the fan to on. This will help thaw out the coils before the technician gets there.

If your AC is making unusual noises, you should call our team for an inspection. Without proper training, you may only cause more damage by trying to complete any repairs yourself, so save yourself the time and hassle and let us take care of the noise.

A programmable thermostat is a simple, cost-saving device to focus temperature control for the times and days you need it most, reducing energy use while you’re at work, school, or on vacation. Smart thermostats will give you remote access to control your comfort settings from anywhere.

A ductless mini-split system started out as a popular cooling solution for homes without central air ducts. With one unit attached outside and one or more small units mounted on a wall inside, the “split” system draws air in, cools it, and ventilates back out without the need for installing ductwork. These are also now being used for heating, even in cold climate areas.

 Rooms not cooling – House is hot – A/C Blowing warm air – Thermostat broken – Freon leaks – Duct leaks- Drain pan leaking – Electric or gas bills too high – Noisy equipment

Contact us to schedule a call if you are experiencing any of these issues. We also offer 24/7 emergency service to get you comfortable again.

Accroymns & Definitions

  • AC : Air Conditioning
  • AC : Alternating Current
  • ACH : Air Changes per Hour
  • ACM : Asbestos Containing Material
  • AFUE : Annual Fuel Efficiency Ratio
  • AHU : Air Handling Unit
  • ASHRAE : American Society of Heating Refrigeration and Air Conditioning Engineers
  • B : Boiler
  • BSLN : Baseline
  • BTU : British Thermal Unit
  • BTUH : British Thermal Units / Hour
  • BY : Base Year
  • CAV : Constant Air Volume
  • CD : Cold Deck
  • CDD : Cooling Degree Days
  • CEM : Certified Energy Manager
  • CFC : ChloroFluoroCarbon
  • CFM : Cubic Feet per Minute
  • CH : Chiller
  • CHW : Chilled Water
  • CLF : Cooling Load Factor
  • CLTD : Cooling Load Temperature Difference
  • COP : Coefficient Of Performance
  • CV : Constant Volume
  • DA : Discharge Air
  • DB : Data Base
  • DB : Dry Bulb
  • DC : Direct Current
  • DCV : Demand Controlled Ventilation
  • DD : Degree Day
  • DDC : Direct Digital Control
  • DH : Duct Heater
  • DI : Digital Input
  • DO : Digital Output
  • DP : Dew Point
  • DP : Differential Pressure
  • DX : Direct Expansion
  • EAT : Entering Air Temperature
  • ECM : Electronically Commutated Motor
  • ECM : Energy Conservation Measure
  • ECO : Energy Conservation Opportunity
  • EDH : Electric Duct Heater
  • EEM : Energy Efficiency Measure
  • EER : Energy Efficiency Ratio
  • EF : Exhaust Fan
  • EH : Electric Heater
  • EMS : Energy Management System
  • ESCO : Energy Service Company
  • EUH : Electric Unit Heater
  • EWT : Entering Water Temperature
  • FCU : Fan Coil Unit
  • FLA : Full Load Amps
  • FPM : Feet Per Minute
  • GPM : Gallons Per Minute
  • HCFC : Hydrochlorofluorocarbon
  • HD : Hot Deck
  • HDD : Heating Degree Days
  • HEPA : High Efficiency Particulate Arresting
  • HFC : HydroFluoroCarbon
  • HL : High Limit
  • HR : Heat Recovery
  • HRU : Heat Recovery Unit
  • HRV : Heat Recovery Ventilator
  • HSPF : Heating Seasonal Performance Factor
  • HVAC : Heating Ventilation and Air Conditioning
  • HWP : Hot Water Pump
  • HWR : Hot Water Return
  • HWS : Hot Water Supply
  • HWRT : Hot Water Return Temperature
  • HWST : Hot Water Supply Temperature
  • HX : Heat Exchanger
  • IAQ : Indoor Air Quality
  • LAT : Leaving Air Temperature
  • LP : Low Pressure
  • LPS : Low Pressure Steam
  • LRA : Locked Rotor Amps
  • LWBT : Leaving Wet Bulb Temperature
  • LWT : Leaving Water Temperature
  • MA : Mixed Air
  • MUA : Make-up Air Unit
  • MZ : Multi-Zone
  • NC : Normally Closed
  • NEMA : National Electrical Manufacturers Association
  • NO : Normally Open
  • OA : Outside Air
  • OAT : Outside Air Temperature
  • PE : Professional Engineer
  • PRV : Pressure Relief Valve
  • PRV : Pressure Reducing Valve
  • PTAC : Packaged Terminal Air Conditioner
  • RA : Return Air
  • RH : Relative Humidity
  • RPM : Revolutions Per Minute
  • RTU : Roof Top Unit
  • SA : Supply Air
  • SAT : Supply Air Temperature
  • SC : Subcool
  • SEER : Seasonal Energy Efficiency Ratio
  • SF : Supply Fan
  • SHFG : Solar Heat Gain Factor
  • SP : Set Point
  • SP : Static Pressure
  • T : Temperature
  • TSTAT : Thermostat
  • TEV : Thermostatic Expansion Valve
  • TXV : Thermostatic Expansion Valve
  • UH : Unit Heater
  • UV : UltraViolet
  • VAV : Variable Air Volume
  • VD : Volume Damper
  • VFD : Variable Frequency Drive
  • VSD : Variable Speed Drive
  • VSP : Variable Speed Pump(ing)
  • WB : Wet Bulb
  • WC : Water Column
  • YTD : Year To Date

What Our Customers Have to Say

Modern HVAC was highly recommended to me. They did a fantastic job on a very complicated heating system conversion/installation that no one else wanted to touch. They have impressive technical skill, knowledge and customer service.
Fantastic company to work with! They do great work and work hard to provide a great customer experience!
Modern was very responsive in repairing my 86 year old mom's AC system that was in need of help. I could not ask for better service

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