Frequent Questions and Answers - FMH HVAC


How are the sizing capacities of heating and cooling systems measured?

The heating and cooling systems are sized according to their tonnage.
One (1) ton equals 12,000 BTU/H. Residential systems can range from 1
to 5 tons.

What size HVAC system should I have?
Contrary to popular belief there, is no rule of thumb for sizing a
system to a home. Depending upon the construction of your home, one (1)
ton of air conditioning can cool anywhere from 300 to 800 square feet
of home. The only way to insure the size of the system you purchase
will be large enough to cool your home, but not any larger than you
need, is to have your home’s individual heating and cooling needs
evaluated by a licensed professional.

How is the efficiency of heating and cooling equipment measured?
The S.E.E.R. (seasonal energy efficiency ratio) is the amount of
cooling your system will deliver per dollar spent on electricity. For
example, a 3-ton unit may have a S.E.E.R. efficiency rating of 13, 14,
or 15. The higher the S.E.E.R. the more efficient the system will be.
The S.E.E.R. rating of any given unit can range anywhere from 13 to 17.

How can I increase the efficiency and life of my home’s heating and cooling systems?
The most important thing you can do is clean and replace your filters
frequently. Also, a system heats and cools more evenly when the blower
is in the “on” position. The blower provides constant air movement
throughout the home, and allows for better filtration. Finally, shades,
drapes, shutters, or screens should be installed on windows that are
exposed to extreme sunlight.

Is a system with more capacity better?
No. A larger system with more capacity delivers less comfort and costs
more to operate. An air conditioner is at its least efficient when
first turning on. A system with too much capacity will run in numerous
short cycles, turning on and off repeatedly, therefore causing it to be
less efficient. Also keep in mind that an air conditioner only removes
humidity when it’s running, so a system with shorter run cycles
doesn’t remove humidity from the air very well.

How long should my system run in a cycle?
There is no exact answer for how long your system should run during
each cycle. The average air conditioner is sized to remove the heat
from your home as fast as it comes in, on a 110° day. Therefore,
ideally, on a 110° day the system should be able to keep up with
the incoming heat, but not gain on it and be able to turn off. The
cooler it is below 110°, the more the system will cycle on and 

Should I try to keep my system from running too much?
Every time your system starts up, it will use a lot of electricity and
not produce much cooling. Usually a system that is too small to cool
the home is more economical to run but delivers less comfort. Even
though it runs nonstop, it will usually consume less power than a
larger system that cycles on and off. As a rule of thumb, a unit that
is either on or off is less expensive than one cycling on and off.

What air temperature should my air conditioner produce?
The air temperature your system produces depends on the temperature of
the air going into the system. Generally, the air produced should be
18°-20° below what enters the system. So if the air entering
the system is 80°, the air exiting should be about
60°-62°. However, that only works on a system that has been
running at least 15 minutes on a warm, dry day with a home that is
about 80° inside. On a mild day, with an indoor temperature in the
low 70′s, or during humid conditions, the air coming out may only
be 15°-17° cooler than what enters.

What temperature should I set my thermostat?
Obviously the time of year becomes a big factor for desired temperature
settings. In the summer months the average temperature setting is
78°-80°, in the winter 70°-72° seems to be the most
common setting. Remember, when leaving your house, try to avoid drastic
temperature changes. Do not set your temperature back more than 5°;
this will cause your unit to work harder to achieve the desired
temperature setting.

What are the advantages of a programmable thermostat?

Different programmable thermostats offer many different features.
However, because they are electronic, they are all more accurate and
efficient than thermostats that contain mercury. With programmable
thermostats you can control the temperature in your home at different
times of day without ever touching your thermostat. Because everything
is automatic, you will never forget to change the setting on your own. TOP

How often should I replace my filters?
For optimum efficiency and filtration, we recommend that you replace
your disposable filters at least once a month. If you have washable
filters, they should be cleaned once a month.

What maintenance should I do on my air conditioner?
The most important maintenance you can do is to change your filters
regularly. Ground mounted outdoor units need to be kept clear of
debris, clutter; weeds or landscaping that can grow too close and
reduce the airflow to the unit. Also, keep pets away from the unit
because pet urine can cause expensive damage. Use caution with a weed
trimmer around the unit to prevent damaging control wiring. Any
additional maintenance should only be performed by qualified personnel.

How often should I have maintenance done on my air conditioner?
You should have maintenance done on your air conditioning system twice
a year. This not only ensures maximum efficiency, it enables us to
foresee any possible problems that may occur in the near future. Our
Comfort Assurance Program (CAP) plan is specifically designed to keep
your air conditioning system running at its peak efficiency year-round.

Is there anything I should check prior to calling for service?

Yes. Check to be sure that the air handler or furnace is plugged in.
Check that the breakers and the disconnects are turned on and be sure
the thermostat is set correctly.

How much does a new replacement system cost?
Due to the many different makes, models and customer needs, price is an
issue that can only be solved by doing a thorough evaluation of your
home and existing equipment. There is no charge for an in-house
replacement proposal.

Are there any air conditioning systems that are safe for the environment?
Yes. Several manufactures have developed new systems that contain the
environmentally friendly R410A, or Puron, refrigerant. Visit our
products page to view our entire line of Puron products.

Do electronic air cleaners really work?
Yes, they can actually play a big part in your complete home comfort.
We have a variety of whole-house filtration devices. Some electronic
air cleaners can even remove dust particles and pollen as small as .10
micron. Visit our products page for more information about the
electronic air cleaners we offer.

Should I close the registers and doors to areas of the home that I do not use on a regular basis?
No. Closing the registers will decrease the systems’ airflow and
efficiency. Every system is designed to cool a certain number of square
feet. By closing registers and doors in certain rooms, you disrupt the
airflow and cause your air conditioning system to work harder to
distribute air to other areas of your home. Your system will work
harder, to cool less space, making it cycle more and become less

Why are humidifiers used more in heating than cooling?

When cool outdoor air enters a home it tends to dry out as it warms up,
which increases the static electricity in the home and causes sinus
problems. Adding a humidifier with help to add moisture back into the
air and limit sinus problems. In the summer, even with outdoor relative
humidity hovering around the single digits, the humidity in your home
tends to be around 40%. The average comfort range for relative humidity
in a home is from 35 to 45%.

During the heating season, my
heat pump delivers warm air, but not hot air, and will operate for long
periods of time. Is that normal?

Yes, this is normal. A heat pump generally produces air that is
80°, which is considered warm, and will heat the house evenly.
However, 80° may feel cool to your hand, which is usually closer to

During the heating season, my
heat pump makes a “whooshing” sound and I feel cool air coming from the
supply registers. Is that normal?

Yes. During the cold weather months, frost will accumulate on the
outdoor coil. This will cause the heat pump to go into a defrost cycle
anywhere from 1-10 minutes, depending on the amount of ice on the coil.
The system will return to the heating mode once the ice is gone.

How do I know if my A/C unit is big enough?
Before purchasing a replacement system you should always make sure your
system is sized properly. Our representative will provide a heat load
calculation to determine the proper size and make the appropriate
recommendation. Remember, bigger is not always better.