Your local One Hour Heating & Air Conditioning has been serving the Carroll, Frederick, Howard, Montgomery, and Washington Counties area since 2000. We promise prompt and professional service to all of our customers. “Always on time, or you don’t pay a dime.”™ We look forward to solving all your heating and air conditioning repair, installation and service needs. Call us now to schedule an appointment.
To visit our local Heating & Cooling Website Click Here.
REQUEST AN APPOINTMENT ONLINE OR ASK AN EXPERT
Available 24/7
2707 Back Acre Circle
Mount Airy, Maryland 21771
License Number: 4818

Keeping abreast of new product knowledge in the HVAC industry so we can provide the homeowner with options to keep their homes comfort in severe weather. Still family owned and operated; we pride ourselves on providing excellent service for you-our customer.
STAFF
GILLIAN COLLINS – OWNER – VICE PRESIDENT
Raised in Gaithersburg and received a degree in Computer Science/accounting from Montgomery College. Gillian worked at HHS/NIDA and Montgomery College as a computer systems analyst for 15 years. She joined her husband, Larry, in the business in 1989. Gillian’s passion, other than her family, is plein air painting. She has won numerous awards and sells her work at local galleries and art shows.
LARRY COLLINS – OWNER – PRESIDENT
Raised in Gaithersburg and received a degree in Microbiology from University of Maryland. Took over his father’s building/remodeling business in 1979 and expanded the company to service residential plumbing and water treatment. Larry holds a Master HVAC, Master Plumbing and Journeyman Electrical licenses. He enjoys spending his spare time target shooting and go-carting with his 3 children and grandsons. To relax his takes walks with his wife, Gillian, of 34 years.
TERRY FISHER – OWNER – GENERAL MANAGER
FEATURED SERVICES
Central and Western Maryland: 301.515.1001
One Hour Air Conditioning & Heating is the residential expert in Central and Western Maryland. We offer top-notch, craftsman installation, warranties, and One Hour Air exclusive guarantees. We also specialize in all aspects of Indoor Air Quality including electrostatic filters, UV lights, Humidifiers, and more. Our highly trained service technicians provide an unparalleled service with straightforward pricing. We are available 24 hours a day, 7 days a week, 365 days a year including holidays! Family owned and operated. Family owned and operated. Up to 60 Months No Interest Financing on HVAC Install!!!
SERVICES
- Air Conditioners
- Air Handlers
- Boilers
- Ductwork
- Furnaces
- Heat Pumps
- Indoor Air Quality
- Maintenance Agreements
- Thermostats
- Duct Cleaning
- Geothermal
- Tankless Water Heater
AREAS SERVED
- Barnesville
- Bethesda
- Brookeville
- Cabin John
- Chevy Chase
- Clarksburg
- Frederick
- Gaithersburg
- Germantown
- Hagerstown
- Ijamsville
- Kensington
- Middletown
- Mount AIry
- Olney
- Poolesville
- Potomac
- Rockville
- Silver Spring
- Carroll, Frederick, Howard, Montgomery, and Washington Counties
At One Hour Heating & Air Conditioning®, we know that every home owner and every home itself is different. As a service partner of Direct Energy®, we are proud to offer the Home ComfortCollection™, protection plans designed to fit your home’s needs.
COMPANY NEWS
-
STIMULUS PACKAGE PAYS OFF FOR CARROLL. FREDERICK, HOWARD, AND WASHINGTON COUNTY HOMEOWNERS
Up to $500 tax credit available to qualified homeowners like you! Ask how you can cash in and also have a more efficient heating and air conditioning system for your family.