This question is twofold. You’ll want to perform preventative maintenance to protect your warranty and make sure the system lasts to full potential.

Yes, we recommend that you get your equipment serviced annually.

Yes. A permit is required on all equipment installations. We provide all permits required from mechanical to electrical (if applicable) and gas piping (if applicable).

No, since units are designed to be outside they do not need a cover.

A zoning system can improve air distribution to your home or business. Most situations do not necessitate a zoning system. We do offer a diverse line of zoning products, but customer should be aware that the duct infrastructure will need to be replaced at the same time.

Here in the Northeast, it is recommended you have your comfort system serviced twice per year, preferably in the spring and fall. This will help ensure that your comfort system is running as efficiently as possible during the heating and cooling seasons. At EXXEL we offer a Precision Tune Up service which will take care of all of your system’s maintenance needs.

We have been serving the Central Maryland area since 2003. We are a smaller family owned company, focused on customer satisfaction. We are certified installers of Lennox Signature, Carrier Infinity, and Mitsubishi Hyper heat. Fully Licensed and insured, unlike some of our competitors. If you are interested in a new comfort system, you will receive the quality and attention to detail that only a small local business can provide.

Air Quality

We offer Merv. 11, Merv. 16 and Air Purification.

You should check your standard 1″ air filter anywhere from 1 months-3 months depending on the filter and where you live. Larger families and pets tend to make filter changes more frequent. Air Cleaners with 5″ pleats usually are good for 6 months to a year.

The frequency of duct cleaning varies depending on the home and the preference of the homeowner. Typically, every 5 years is sufficient. There are a few things to consider when thinking about how often to have your ducts cleaned:

  • Do you have pets that shed a high amount of hair and dander?
  • Do you have smokers in your household?
  • If anyone in your household has allergies, you may want to have your ducts cleaned more often.
  • If you just moved into a home, it may be a good idea to have the ducts thoroughly cleaned.
  • After a home remodeling, a heavy amount of dust and debris can be generated during a renovation.

A thorough duct cleaning will usually cost between $300 and $500, depending on the size of the home. Beware of companies offering cut-rate duct cleaning services. This is a well-known bait and switch tactic, and you could end up paying much more than you expected, or the company may not perform a proper duct cleaning. The Better Business Bureau has issued a warning about such services.

Carbon monoxide, also known as the “silent killer,” is a big problem. A failed natural gas furnace or other appliance can release poisonous CO gas into your home. The problem is that carbon monoxide is colorless and odorless, meaning that without proper precautions, you won’t know if there is a problem. We offer low-cost accessories that can alert you if you ever have a problem with carbon monoxide in your home, helping you breathe easier!


AFUE is efficiency rating of the fuel burning appliance. 80% AFUE rated appliances use a metal exhaust vent and loose 20% of the heat through combustion in the exhaust gases that are vented outside.

High efficiency equipment (90% +) use a PVC vent, and heat loss through the venting is minimized. This type of equipment uses a secondary counter flow heat exchanger, and exhaust gas temperatures are so low, that they form condensation.

HSPF stands for Heating Seasonal Performance Factor. This rating is associated with how much heat a heat pump is able to bring into the home during the winter season.

AHRI is a website that gives ratings on the equipment.

This is the Seasonal Energy Efficiency Rating. This is associated with the Air conditioning systems performance averaged throughout the entire cooling season.

This rating correlates to the amount of energy the air conditioner uses at peak energy loads.

Heat Pumps

It is time to replace your heat pump when it won’t work anymore, it’s 15 years or older, or if it’s a R-22 unit.

Not necessarily, larger doesn’t always mean better. You would probably want to look into getting a more efficient variable speed system.

No. We recommend leaving this one to the professionals. If your heat pump needs to be repaired feel free to give us a call at 443-821-1040

No. If you put a cover on your heat pump and the system turns on, the system will no longer work.

A heat pump is a system that can reverse refrigerant flow to either heat or cool a controlled space.

Heating & Cooling

The size of your system really depends on your home and your needs. To help you make this decision we offer free in-home energy consultations. We will perform load calculations to confirm we are properly sizing your new equipment. Feel free to give us a call to schedule your consultation today!

To find the perfect heating and cooling system for you we recommend one of our free in-home energy consultations. Feel free to give us a call to schedule your consultation today!

The best way to heat and cool really depends on what fuels are available at your home.

You should purchase a new heating or air conditioning system so that you can maintain optimum comfort year round.

The most efficient way to run a heating and cooling system is to just leave it on. Take advantage of your programmable thermostat where you don’t have to worry about turning the system off or on, just let the programming do the work.

An inverter and variable speed cooling are two different types of compressors.

Modulating heating is variable capacity heating used in fossil fuel burning appliances. The draft induction motor will rev up or down based on the need for heat, and the amount of fuel needed for the appliance to burn efficiently will be regulated by the control valve to correspond to demand.

This all depends on size of house and duct work.

Since R-22 has been phased out, parts and refrigerant are hard to come by which often make them quite expensive.

Yes, when it comes time to repair your system, parts and refrigerant will be a lot more reasonably priced.

R-22 is the older refrigerant used in air conditioning units. R-410A is not only newer, but it is also more environmentally friendly.

In two-stage cooling there’s a low stage and high stage.

Depending on general maintenance, systems can last anywhere from 10-20 years. To last as long as possible, we highly recommend an annual general maintenance.

The minimum energy efficiency standard for air conditioners in MD is 14 SEER.

R-22 is no longer available, R-410A is the standard replacement.

A variable-speed furnace benefits you on the cost and noise of running the system.

Not necessarily. Just because a certain size of furnace or comfort system was previously installed in your home does not mean that system was correctly sized for your home. When it comes to home comfort systems, it is extremely important to size the system correctly. An improperly sized system can cause problems with comfort and efficiency, and could also lower the useful life of your equipment.

Unfortunately, not all HVAC companies are made equal, and not all of them do an adequate job of correctly sizing a system. Beware of any HVAC company that offers to replace your furnace, air conditioning unit, or comfort system without doing a proper heat loss calculation. Simply counting registers is not enough to ensure proper sizing! In many instances, especially with today’s variable speed and modulating technology, previous systems have been oversized compared to what is needed for the home. Not only does a smaller system cost less to purchase and install, but a correctly sized system will run at optimal efficiency and will provide the greatest comfort.

There are several possible explanations for this:

  • The behavior of the members of your household may have changed. Examples may be turning the heat up higher for a longer duration, leaving windows open, taking longer showers, etc.
  • Outdoor temperatures and weather may be different this year than last year
  • You added air conditioning when you previously did not have it in your home.
  • Energy prices may have risen.
  • You may have a problem with your ductwork or insulation.
  • Your system may not have been properly installed.
  • Your system may not have been properly sized for your home before installation.

Here are a few questions you should ask yourself:

  • How long do I plan on living in my home? The answer to this question will affect the return on investment of any high-efficiency system.
  • How concerned am I about my family’s carbon footprint?
  • Is having a comfortable home a high priority for me and/or my family?
  • Does anyone in my family suffer from allergies? If so, you may consider exploring some Indoor Air Quality products such as improved filters, air cleaners, or UV air purifiers.

Of course, like any machine, proper maintenance is important in maximizing the life of your comfort system. We recommend getting a Precision Tune-Up twice per year. These services are included with our Gold and Silver memberships.

It is also important to ensure that your comfort system is properly sized for your home when it is installed. Improper sizing can lower the useful life of a comfort system, cause it to run at a lower efficiency level, and reduce the comfort level of your home. Make sure your HVAC contractor does a proper heat loss calculation before they install your system!

Today’s thermostats offer a wide range of energy saving and comfort options. Most thermostats today give you the ability to program them for optimal comfort and efficiency. Higher end models can provide “energy monitoring” features, showing you which appliances in your home are using up more energy, and at which times of the day. Give us a call or ask your comfort advisor about thermostat options if you would like more information.

Strange Sounds

Clinks, pops, squeaks, or grinding. If you are hearing sounds that the unit never made before then it is time to call a professional. Even if the system still provides you with adequate temperature control, the sounds are an indication of am issue that lif left untreated will likely develop into a more expensive repair.

Water or Moisture

Look around the system. Is there lots of condensation or perhaps pools of water? This could be either a problem with the refrigerant which has started to leak or a problem with the drainage system. If you find these issues in your HVAC system, then maintenance or repairs should be the next step.

Odd smells

If you find that there is a pungent odor from your HVAC system, then there are usually two possibilities. 1) there is a problem with the wiring and some of the insulation has burnt away. 2) If the small is musty, then it means that there is pooled water in the system that has become a breeding ground for mold and mildew.

Inaccurate Thermostat

are different rooms different temperatures even though they are controlled by the same thermostat? This could be an issue with the thermostat itself for possibly the duct work.

Contact Exxel


Air Conditioning

Our HVAC technicians will make sure all your Maryland home stays cool during the summer.


We’ll help repair, maintain, or replace your heating system to make sure it’s functioning properly.

Indoor Air Quality

We offer several tiers of air purification to fit your needs. We also offer HRV, humidifiers, & installation of smart thermostats.


We will help you choose the perfect size generator, the right fuel source & the best installation locations for your generator & transfer switch.