FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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(Print or Type Responses)

1. Name and Address of Reporting Person * Lane Brian E.   2. Issuer Name and Ticker or Trading Symbol COMFORT SYSTEMS USA INC [FIX] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) President/Chief Executive Off. (Last) (First) (Middle) C/O COMFORT SYSTEMS USA, INC., 675 BERING DRIVE, SUITE 400 3. Date of Earliest Transaction (Month/Day/Year) 03/07/2018 (Street) HOUSTON, TX 77057 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 03/07/2018   A   10,094 (1) A $ 0 193,726 D   Common Stock 03/07/2018   A   15,140 (2) A $ 0 208,866 D   Common Stock 03/07/2018   F   5,958 (3) D $ 42.5 202,908 D

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Employee Stock Option (Right to Buy)

$ 42.5

03/07/2018

A

32,873

04/01/2019(4)

03/07/2028(5)

Common Stock

32,873

$ 0

32,873

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Lane Brian E. C/O COMFORT SYSTEMS USA, INC. 675 BERING DRIVE, SUITE 400 HOUSTON, TX 77057	X		President/Chief Executive Off.

Signatures

/s/ Trent T. McKenna, by power of attorney		03/09/2018
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	Each restricted stock unit granted on March 7, 2018 represents a right to receive one share of common stock and will vest in equal installments over a three-year vesting schedule.
(2)	Reflects dollar-denominated performance restricted stock units granted on March 25, 2015 that vested on March 7, 2018. These units vested as a result of the Company's 2015-2017 relative Total Shareholder Return and 2015-2017 Company average EPS - the applicable performance measures.
(3)	Forfeited shares are related to dollar-denominated performance restricted stock units that vested on March 7, 2018 and were priced based on the closing price of the Company's common stock on March 7, 2018.
(4)	Stock options vest in equal installments over a three-year vesting schedule.
(5)	Stock options expire at the earlier of ten years from the date of grant or three months following termination of employment.

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