Everett W. Long, 79, the founder of a plumbing and heating company in Northern Virginia and a life-long resident of the Washington area, died Tuesday at his winter home in Harbour Heights, Fla.

Mr. Long, who also maintained a home in Fairfax, started his business, now known as Long's Corp., in 1936. He went into semiretirement in 1960 and full retirment in 1965. The firm is run by two of his sons, Everett N. of Annandale, and Kenneth A., of Haymarket.

A native of McLean, Mr. Long grew up in Fairfax County. He served in the Army from 1919 to 1922. He worked briefly for a brick company in Baltimore and for 13 years for a heating oil company in Arlington. He then became an independent contractor.

Mr. Long was active in Masonic groups and was a member of the Henry Lodge No. 57, the Elmer Timberman Lodge in Annandale, of which he was a founder, the Kena Temple of the Shrine and Hope Chapter No. 73 of the Order of the Eastern Star. He also was a past-president of the Fairfax Rotary Club.

In addition to Everett and Kenneth Long, survivors include his wife, Helen, of Fairfax and Harbour Heights; a third son, Calvin, of Gainesville, Fla.; three brothers and three sisters; six grandchildren, and six great-grandchildren.