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EXHIBIT 21

LIST OF SUBSIDIARIES OF THE REGISTRANT
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Company Name State of Incorporation
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1st Call Heating & Cooling, Inc. Michigan

A-1 Air Conditioning, Inc. Tennessee

AC/DAC, L.P. Tennessee

Academy Air Service Experts, Inc. Tennessee

Ainsley & Son Heating, Inc. Tennessee

Air Conditioning and Heating, L.P. Tennessee

Air Experts, Inc. Georgia
d/b/a Massengale Heating and Air

Air Systems Acquisition Sub, Inc. Tennessee

Alert Heating Service, Inc. Tennessee

All American Air Conditioning & Heating, Inc. Tennessee

Allbritten Plumbing, Heating and Air Conditioning Tennessee
Service, Inc.

Andros Refrigeration, Inc. Tennessee

Arrow Heating & Air Conditioning, Inc. Wisconsin
d/b/a Air Comfort Heating & Sheet Metal

Artic Aire of Chico, Inc. California

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COMPANY NAME STATE OF INCORPORATION
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Astron Residential, Inc. Tennessee
d/b/a Comfort Tech Cooling & Heating

Atlantic Air Conditioning and Heating, Inc. Tennessee

Austin Brothers, Inc. Tennessee
d/b/a Mesa Aire, Inc., Mesa Aire Service Experts

B&M Heating & Cooling, Inc. Tennessee

Becht Heating & Cooling, Inc. Indiana

Ben Peer Heating, Inc. Tennessee

Berkshire Air Conditioning Company Tennessee
d/b/a Frontier Heating & Cooling

Bill Ingraham Service Company, Inc. California

Bill's Commercial Air Conditioning, Inc. Tennessee

C. Iapaluccio Company, Inc. Connecticut
d/b/a The Original Hearth Shop

Chief/Bauer Heating & Air Conditioning, Inc. Tennessee

Claire's Air Conditioning and Refrigeration, Inc. Tennessee
d/b/a Service Experts of Wichita Falls, Service Experts of
the Permian Basin, Claire & Sanders Service Experts,
Claire's Service Experts, Alpine Air Conditioning

Climate Control, Inc. Tennessee

Climate Design System, Inc. Tennessee

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COMPANY NAME STATE OF INCORPORATION
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Climate Masters Service Company Colorado

Coastal Air Conditioning Services, Inc. Georgia

Comerford's Heating & Air Conditioning, Inc. California

Comfortech, Inc. Tennessee

Contractor Success Group, Inc. Missouri

Custom Air Conditioning, Inc. Tennessee
d/b/a Service Experts of Palm Beach, Dan's Air
Conditioning & Heating

Dan Jacob's Heating & Cooling, Inc. Tennessee
d/b/a Kautz Heating & Air Conditioning, Inc.

Davis the Plumber, Inc. Tennessee

DeLand Heating & Air Conditioning Company Tennessee

Dial One Raymond Plumbing, Heating & Cooling, Inc. Tennessee
d/b/a Dial One Service Champions, Ace Superior

Dodge Heating & Air Conditioning, Inc. Georgia

Doler Plumbing & Heating, Inc. Indiana

Economy Heating and Air Conditioning, Inc. Tennessee
d/b/a Allied Heating and Cooling Co., Brentwood Heating
& Cooling

Eisenbach Enterprises, Inc. Texas

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COMPANY NAME STATE OF INCORPORATION
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Epperson, Inc. Tennessee

Eveready Corporation Tennessee

Falso Service Experts, Inc. New York
d/b/a Falso Heating and Sheet Metal

Fras Air Conditioning, Inc. New Jersey

Frees Service Experts, Inc. Texas
d/b/a Service Experts of Northwest Louisiana

Freschi Air Systems, Inc. Tennessee

Gaddis Co. Tennessee
d/b/a Desert Air Conditioning

George B. Givens Company, Inc. Tennessee
d/b/a New Age Plumbing

Getzschman Heating & Sheet Metal Contractors, Inc. Tennessee

Gilley's Quality Heating & Cooling, Inc. Tennessee

Gordon's Specialty Company Tennessee
d/b/a Service Experts

Gregory's Plumbing Co., Inc. Oklahoma

Gulf Coast Cooling, Inc. Tennessee
d/b/a Service Experts of Southwest Florida

Hardwick Air Masters, Inc. Arkansas
d/b/a Service Experts of Arkansas

COMPANY NAME STATE OF INCORPORATION
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Holmes Sales & Service, Inc. Tennessee

J.M. Jenks Incorporated Utah
d/b/a JM Mechanical Systems

Jack Nelson Co., Inc. Oklahoma

Jansen's Heating & Air Conditioning, Inc. Illinois

Kenneth E. Martin, Inc. Georgia
d/b/a Air Tronics Company

Knochelmann, Inc. Tennessee
d/b/a Knochelmann Plumbing, Heating & Air
Conditioning, Clifton Heating & Air Conditioning,
Comfort Air, Knochelmann Service Experts

Kozon, Inc. Tennessee

Lake Arbor Heating, Inc. Colorado
d/b/a Westside Heating & Air Conditioning

Lee Voisard Plumbing & Heating, Inc. Tennessee

Local Furnace Co., Inc. Tennessee

Mathews Air Conditioning and Heating, Inc. Tennessee

Matz Heating & Air Conditioning, Inc. Tennessee
d/b/a Right Way Heating and Air Conditioning Service

McPhee, Inc. Colorado
d/b/a McPhee Plumbing & Heating, Inc.

Mid Fla Heating and Air, Inc. Tennessee

Midland Heating & Air Conditioning, Inc. Tennessee

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Company Name State of Incorporation
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Neal Harris Heating & Air Conditioning Company, Inc. Missouri

Norrell Heating and Air Conditioning Company, Inc. Alabama

Pardee Refrigeration Company Incorporated Tennessee
d/b/a Pardee Heating & Air Conditioning, Mac-Huff, Inc.,
H&M Heating & A/C, Pardee Service Experts, Island Air
Service Experts, Service Experts of Charleston

Parker Heating and Air Conditioning, Incorporated Tennessee

Parrott Mechanical, Inc. Idaho
d/b/a Snappy Plumbing

ProAir Acquisition Sub, Inc. Tennessee
d/b/a Peachtree-Cherokee/Edwards Heating & A/C,
Plano Air Mart Services

PTM Enterprises, Inc. Georgia
d/b/a Macy's Air Conditioning & Heating, Bulldog
Heating & Air Conditioning

R&M Climate Control, Inc. Tennessee

Roland J. Down, Inc. New York
d/b/a Kool Temp, Pipe Solutions, Sunset Sheet Metal

Rolf Coal and Fuel Corp. Indiana
d/b/a Griffin Heating & Air Conditioning, Inc., Rolf
Heating & Air Conditioning

Russell Mechanical, Inc. Texas

S&W Air conditioning, Inc. Tennessee
d/b/a/ S&W Services

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Company Name State of Incorporation
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Safari Services, Inc. Florida
d/b/a Joe's Air & Heat

Sanders Indoor Comfort, Inc. Tennessee
d/b/a Dgree Heating & Air Conditioning

SEI Holdings, Inc. Delaware

SEI Management Company, LLC Tennessee
d/b/a Travel Experts

SEI Management Subsidiary, Inc. Tennessee

SEI Newco, Inc. Tennessee

SEIIN GP, Inc. Indiana

SEITN GP, Inc. Tennessee
d/b/a Donelson Air Conditioning Company, AC Service
and Installation, Air Conditioning & Heating
Unlimited

SEITN LP, Inc. Delaware

Service Experts DFW, Inc. Tennessee
d/b/a Air Experts, Alliance Air Conditioning & Heating

Service Experts of Clearwater, Inc. Tennessee

Service Experts of Indiana, L.P. Tennessee
d/b/a B.W. Heating & Cooling, Brand Heating & Air
Conditioning, Service Experts of Indianapolis

Service Experts of Indianapolis, Inc. Indiana

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Company Name State of Incorporation
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Service Experts of Palm Springs, Inc. California

Service Experts of Raleigh, Inc. Tennessee
d/b/a Piedmont Air Conditioning Co.

Service Experts of Salt Lake City, Inc. Tennessee
d/b/a Thompson and Sons Heating and Air
Conditioning Company

Service Experts of Utah, Inc. Utah
d/b/a Royden Commercial Services, Inc.,
David M. Steed

Service Experts Services, LLC Tennessee

Shelburne Refrigeration, Inc. California

Steel City Heating & Air, Inc. Alabama

Strand Brothers, Inc. Tennessee

Sunbeam Service Experts, Inc. New York
d/b/a Fleischmann Heating & Cooling

Sylvester's, L.P. Tennessee
d/b/a Sylvester's Corp.

Sylvesters Corp. Indiana

Teays Valley Heating and Cooling, Inc. West Virginia

The McElroy Service Company Nebraska

TML, Inc. Idaho

Total Comfort Specialists California

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Company Name State of Incorporation
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Triton Mechanical, Inc. Tennessee

Venture International, Inc. Tennessee
d/b/a Ron Smith and Associates