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EXHIBIT 21.1

SUBSIDIARIES OF COMFORT SYSTEMS USA, INC.
As of February 26, 2009

ENTITY NAME	DOMESTIC JURISDICTION		FORMATION DATE
ACI Mechanical, Inc.		Delaware		06/26/1998
ARC Comfort Systems USA, Inc.		Delaware		03/17/1998
Accurate Air Systems, Inc.		Delaware		06/29/2007
Accu-Temp GP, Inc.		Delaware		05/21/1998
Accu-Temp LP, Inc.		Delaware		05/20/1998
Air Systems Engineering, Inc.		Washington		05/18/1973
AirTemp, Inc.		Delaware		10/15/1998
Atlas-Accurate Holdings, L..L..C.		Delaware		12/28/1998
Atlas Comfort Systems USA, Inc.		California		07/31/2007
Atlas Comfort Systems USA, L.L.C.		Delaware		06/29/2007
Batchelor's Mechanical Contractors, Inc.		Alabama		03/16/1981
BCM Controls Corporation		Massachusetts		10/03/1984
California Comfort Systems USA, Inc.		California		05/18/1983
Climate Control, Inc.		Delaware		09/17/1998
Comfort Systems USA (Arkansas), Inc.		Delaware		03/17/1998
Comfort Systems USA (Atlanta), Inc.		Georgia		01/25/2005
Comfort Systems USA (Baltimore), Inc.		Delaware		10/15/1998
Comfort Systems USA (Bristol), Inc.		Delaware		08/25/1997
Comfort Systems USA (Carolinas), Inc.		Delaware		06/09/2006
Comfort Systems USA (Florida), Inc.		Florida		10/04/1976
Comfort Systems USA G.P., Inc.		Delaware		08/12/1998
Comfort Systems USA (Hartford), Inc.		Delaware		08/25/1997
Comfort Systems USA (Intermountain), Inc.		Utah		05/06/1969
Comfort Systems USA (Kentucky), Inc.		Kentucky		02/10/1981
Comfort Systems USA National Accounts, LLC		Indiana		07/28/1998
Comfort Systems USA (Ohio), Inc.		Ohio		10/10/1979
Comfort Systems USA (Pasadena), Inc.		Texas		06/29/2007
Comfort Systems USA Puerto Rico, Inc.		Puerto Rico		05/31/1998
Comfort Systems USA (Southeast), Inc.		Delaware		03/24/1998
Comfort Systems USA (Syracuse), Inc.		New York		03/08/1965
Comfort Systems USA (Texas), L.P.		Texas		08/14/1998
Comfort Systems USA (Twin Cities), Inc.		Minnesota		08/01/2001
Comfort Systems USA (Western Michigan), Inc.		Michigan		07/21/1989
Conditioned Air Mechanical Services, Inc.		California		02/21/2001
CS53 Acquisition Corp.		Delaware		01/26/1999
Delcard Associates, Inc.		Delaware		06/23/2000
Design Mechanical Incorporated		Delaware		10/30/1997
Eastern Heating & Cooling, Inc.		New York		12/19/1988
Eastern Refrigeration Co., Inc.		New York		01/30/1990
Granite State Holdings Company, Inc.		Delaware		11/02/2005
Granite State Plumbing & Heating, LLC		Delaware		07/31/2001
H & M Mechanical, Inc.		Delaware		06/25/1998
Helm Corporation		Colorado		10/26/1972
Hess Mechanical Corporation		Delaware		03/17/1998
Hudson River Heating and Cooling, Inc.		Delaware		08/19/2005
H-VAC Supply, L.L.C.		Puerto Rico		10/18/06
HydroKool, L.L.C.		Delaware		03/16/2006
Madera Mechanical Company		Arizona		06/02/1983

ENTITY NAME	DOMESTIC JURISDICTION		FORMATION DATE
Mechanical Technical Services, Inc.		Delaware		06/29/2007
Merit Mechanical, Inc.		Washington		02/14/1984
MJ Mechanical Services, Inc.		Delaware		12/12/1997
North American Mechanical, Inc.		Delaware		03/17/1998
Quality Air Heating and Cooling, Inc.		Michigan		09/10/1980
Quality Professional Employer Organization LLC		Delaware		12/01/2004
Riddleberger Brothers, Inc.		Virginia		12/22/1958
S.I. Goldman Company, Inc.		Delaware		03/17/1998
S.M. Lawrence Company, Inc.		Tennessee		03/08/1973
SA Associates, Inc.		Utah		03/27/1984
Salmon & Alder, LLC		Utah		07/08/1996
Seasonair, Inc.		Maryland		10/28/1966
Sheren Plumbing & Heating, Inc.		Delaware		01/26/1999
Temp-Right Service, Inc.		Delaware		09/25/1997
The Bengtsson Group, Inc.		Arizona		04/15/1997
The Capital Refrigeration Company		Delaware		08/06/1998
Tri-City Mechanical, Inc.		Arizona		12/23/1977

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SUBSIDIARIES OF COMFORT SYSTEMS USA, INC. As of February 26, 2009