Heater grew up in a Mormon family and at the age 19 served as missionary of The Church of Jesus Christ of
Latter-day Saints. He then served in the United States Armed Forces, after which he worked as an usher in a theatre in Los
Angeles while studying to be an opera singer. He moved to New York City to study singing further and
in 1951 he made his Broadway debut as a singer and juggler in the original cast of Top banana.
In 1952, he was the baritone member of the trio in the world premiere at Brandeis University of Leonard Bernstein's Trouble
Heater began his career as a classical singer in the United States in 1954, singing baritone parts in oratorios and other concert works.
His first opera performances were given at Theater Basel in 1956–1957. He was then committed to the Deutsche Oper Berlin from
1957–1959 and the Vienna State Opera from 1959–1961. Among the roles he sang during this portion of his career were Escamillo in
Georges Bizet's Carmen, Germont in Giuseppe Verdi's La traviata, Sharpless in Giacomo Puccini's
Madama Butterfly, and Silvio in Ruggero Leoncavallo's Pagliacci. His final performances as a baritone were in
1961 with the San Francisco Opera: Demetrius in Benjamin Britten's A midsummer night's dream, the boyar Schelkalov in
Mussorgsky's Boris Godunov, Henry Ashton in Donizetti's Lucia di Lammermoor, Ping in Puccini's Turandot and Tom
Henney in the premiere of Norman Dello Joio's Blood moon.
1961–1964, Heater concentrated on re-training his voice as a tenor, first with Mario del Monaco Another one,
Del Monaco must have been very busy teaching. in Milan and later with Max
Lorenz in Munich. His first performance as a tenor was in the title role of Hans Werner Henze's König Hirsch at the Bavarian State Opera
in 1964. The performance was a great success and he became the leading dramatic tenor at the opera house from 1964–1968; drawing
particular acclaim for his portrayal of Wagnerian heroes like Siegmund in Die Walküre, Tristan in Tristan und Isolde, and the
title roles in Lohengrin, Parsifal, Siegfried, and Tannhäuser. Other important roles at that house were Florestan in Ludwig
van Beethoven's Fidelio, Samson in Camille Saint-Saëns's Samson et Dalila and the title role in Verdi's Otello.
Outside of Munich, Heater worked actively a guest artist at important opera houses during the 1960s and 1970s. His performance
credits include appearances at De Nederlandse Opera, the Deutsche Oper Berlin, the Grand Théâtre de Bordeaux, the Grand Théâtre
de Genève, the Hamburg State Opera, the Hungarian State Opera House, La Fenice, La Monnaie, La Scala, the Liceu, the Semperoper,
and the Staatsoper Stuttgart among others. He sang the roles of Siegmund and Tristan at the Bayreuth Festival in 1966, the latter of
which was recorded live for television and later released on video. He also gave an admired portrayal of Tristan at the Festival
dei due mondi in 1968.
Actually Heater was taught by Tommy Lo Monaco who taught him the Stanley method, a voice killer (see Shirley, Hadley).
His voice did not sustain the big Wagnerian roles. He was derided
in the French press as the hero of of a mini ring
(i. e. a ring with large cuts) as completely over his head.