Born 1988 in Minneapolis, Minnesota (USA), Andrew received his first organ lessons with 12 years of age from Steve Gentile and took piano lessons with the late teachers Roderick Teh and Gary Sipes. He worked many years as an organist and piano accompanist. He is also a composer, who has had several smaller works published through Leupold Editions (Colfax).
Tessman studied from 2013 until 2017 in the university and festival city of Bayreuth, where he obtained his Bachelor of Music in "Künstlerisches Orgelspiel" ("artistic organ playing") with the professors Mareile Krumbholz (born Schmidt) and Matthias Neumann. He also continued piano with Marie-Luise Alcántara (Göbel). Tessman also holds two associate diplomas (ATCL) from Trinity College London, which he obtained through exams in the subjects of Organ (Recital) and Piano Accompanying.
During his time in Bayreuth, he was a substitute organist for many of the churches around the city, both lutheran and Catholic. In November 2015 he was primarily active in the Catholic church Heilig Kreuz ("Holy Cross"), where he also regularly organized concerts under the title of "Heilig Kreuz Concert Series". He has performed in many cities and countries, including the German cities of Bonn, Munich and Hamburg, England, Ireland, in his home state, and on the Faroe Islands.
From December 2017 until August 2018 he was the C-level organist of the lutheran Johanneskirche in Cologne-Porz. At current he is the organist of the Cloister and Pilgrimage site Maria Martental in the Eifel. Additionally he accompanies various choirs in and around the area of Bonn.