Excel Mechanical - HVAC  - Residential - Commecial - Industrial

392 McGrath Highway
Somerville , MA
Tel: 617.628.1144
Tel: 888.636.4822


Excel Mechanical offers multiple options and solutions for residential heating, cooling and indoor air quality

A Residential Split System Central Air Conditioning system keeps your entire home cool in the warmer months, while it helps lower indoor humidity levels.

The system includes a compressor, a fan, condenser coil, evaporator coil, and a refrigerant. It extracts heat from indoor air and transfers it outside, leaving the cooled indoor air to be recirculated.
The efficiency of central air conditioning systems is rated using SEER ratios.

SEER = Cooling Efficiency

"SEER" is a measure of cooling efficiency for air conditioning products. SEER stands for Seasonal Energy Efficiency Ratio. The higher the SEER rating number is, the more energy efficient the unit. The government's established minimum rating for air conditioning is 13.
A central air conditioning system uses electricity as its power source, and requires:

  • An outdoor section (the condensing unit).
  • A matching indoor gas or oil furnace with coil, or air handler.
  • Ductwork to transfer the cooled air throughout the home.

Excel Mechanical, Inc. offers a wide variety of Residential Split System Central Air Conditioning systems in different sizes and efficiencies from a variety of distributors including Carrier, York, Mitsubishi and Daiken.

Ductless systems are units that combine features of central cooling systems and window units. Like larger central cooling systems, there are two components, an indoor unit that delivers the cold air and an outdoor component that discharges the hot air to the outside. Like window units, there is no ductwork to deal with, so you have a greater choice on where to install the system and it can be mounted on the wall, ceiling or floor. A remote control allows you to choose the fan speed and temperature from anywhere in the room.

A Residential Split System Heat Pump is a year round comfort system. In the summer it works like a traditional air conditioning system and draws heat out of your home to keep it cool, and in the winter it works as a heating unit that draws heat from outside air into your home to keep it warm. Many heat pump installations have a booster electrical resistance heater that automatically supplements heat brought in from the outside. Outside air always has heat in it -- even at very low outdoor temperatures.

Like a central air conditioning system, it includes a compressor, a fan, outdoor coil, indoor coil, and a refrigerant.
The efficiency of Heat Pumps is rated using SEER (for cooling efficiency) and HSPF (for heating efficiency).
A Heat Pump uses electricity as its power source, and requires:

  • An outdoor Heat Pump section.
  • Ductwork to transfer the heated or cooled air throughout the home.
  • Electric Media Air Filters
  • Electronic air cleaners can remove up to 95% of airborne dust, pollen, odors, tobacco, and cooking particles. Advanced passive media filters are up to five times better at cleaning than typical furnace filters. Both are installed in your home's ductwork, typically adjacent to a furnace or air handler.
  • Effective filtration systems can help maintain or improve the operating efficiency of heating and cooling equipment. Operating costs savings have been projected as high as 15% over the life of the system. Our consumers are able to choose from a variety of different products from Aprilaire, Honeywell and Carrier.

High efficiency direct vent furnaces provide comfort and energy cost savings with operating efficiencies up to 98 %!  We use a variety of furnaces to suit your needs including Carrier, York, and others.

A Heat Recovery Ventilator exchanges stale indoor air for fresh outdoor air with minimal heat loss. In winter, warmth from the indoor air being vented out is transferred to the outside air being drawn in. The system can effectively control moisture and pollutants .

Indoor Air Quality and Allergy Relief
Home comfort is more than just heating and air conditioning. It also depends on regulating the flow of heat, eliminating drafts, and improving the quality of the air you breathe. To find out more on how Excel Mechanical can help allergy sufferer's see the helpful information below. To view the types of filters we use as well as their advantages please click here.
Indoor Air Problems
Air pollution can be as big a problem inside as out.  People who suffer from allergies can tell you that their symptoms are sometimes just as bad in the home as they are when they are outside.   This is because contaminants like pollen, dust, mold and bacteria are trapped inside our homes and are endlessly recalculated through inefficient as out. This is because contaminants like pollen, dust, mold and bacteria are trapped inside our homes endlessly recalculated through inefficient filtration systems not designed for the volume or small size of these particles. Most standard fiber glass-mesh furnace filters only trap about 7-10% of these particles.
Searching for Relief
Modern filter systems can remove up to 95% of all airborne particles including bacteria, molds and pollen. Allergy sufferers can breathe more easily in a properly filtered home. We recommend either a mechanical or electronic air cleaner depending on the severity of the allergy.
Thicker Filter is Better
Not surprisingly, the thicker the filter material, the better it is at removing small particles.  Our most efficient air cleaners have up to nine inches of filter material and remove up to 95% of allergy causing particles.  One inch filters cannot even come close to this. Do not be mislead by claims of 85% efficiency by one inch thick filters. These ratings are for particles of 5 microns or larger. The rating for common allergy causing particles smaller than the eye can see is closer to 10-20%.
Buyer Beware
One-inch filters, whether electrostatic, electronic or pleated, do not adequately filter out allergy causing or smudging type particle sizes.  And without regular cleaning (every four weeks) the restricted airflow can cause furnace and air conditioner damage, high utility bills and poor heating or cooling.

Types of Filters: Advantages and Disadvantages

Type of Filter





Only 7-10% efficient removing only the large dust particles you can see. Particles you can't see are not filtered at all.

1" Electrostatic Air Filter

• Low Cost
• Fits most existing furnaces
• 85% efficiency in cleaning dust particles 5 microns or larger

• Must wash every 30 days
• Waiting too long to wash filter will cut off airflow and lead to substantially increased heating and cooling costs

Mechanical Air Cleaner

• Lower cost than electronic filter
• Easy to clean every 9-12 months
• Average efficiency is 75% for smaller particles
• Best for severe allergies, including allergies to gases

• Cost of replacement filter is $38-$45 per year
• Waiting too long to replace filter will cut off airflow and lead to substantially increased heating and cooling costs

Electronic Air Cleaner

• Most efficient type of air filter
• 99% efficiency when clean
• Average 90% efficiency overall. Especially good at removing smudging particles
• Easy to wash in the dishwasher
• Best at removing bacteria and molds
• Best for severe allergies
•Carrier control pack warranty for five years parts and labor
• Does not reduce airflow when it gets overloaded with dirt

• Moderately expensive
• Loses efficiency if not washed within 60 days
• Not for persons with allergies to gasses such as auto fumes, when residing near expressway with heavy traffic
• Possible repair expenses on some parts when out of warranty

Hepa Filter

• Most efficient type of air filter there is
• 99.7% efficiency at .3 microns or larger
• Nearly 99.97% efficient at .3 microns and smaller
• Used in hospitals and clean rooms for electronic manufacturing
• Best for allergies to particulates and gasses
• Does not affect furnace efficiency

• Higher cost than regular filters
•Cost of replacement filter yearly


Residential Single Package System is a year 'round comfort system in which all equipment is self-contained in one unit and installed outdoors, typically on a concrete slab or other platform.

In the summer, a single package system provides the comfort of central air conditioning. During the colder months, the unit provides heat. Essentially, it is an air conditioner and heating unit in a single package, hence the name.
Models are available using:

  • Electricity for resistance heating and cooling.
  • Gas for heating and electricity for cooling.
  • Heat pump models using electricity.

The efficiency of single package units is rated using SEER (for cooling efficiency), AFUE% (for gas heating efficiency) and HSPF (for heat pump efficiency). Ductwork is required to transfer the heated or cooled air throughout the home. .

LZone Control Systems eliminate "hot and cold spots" and can help save energy. A Zone Control System splits your house into areas with common heating and cooling requirements, and puts every "zone" under the control of its own thermostat. Each zone is effectively heated or cooled independently of the others. A system of electronically controlled dampers directs heated or cooled air to where it is needed -- reducing energy bills as much as 30%.

Excel Mechanical, Inc. offers a wide variety of Zone Control Systems in different sizes and efficiencies from a variety of distributors including Honeywell and Aprilaire.