Infinity energy organisation ltd. Participants who are customers of a tesp are subject to the following administration fees. Which says: 'the grant vortex pro combi 26 oil-fired combination boiler was far better than the others we tested it loses little heat from its casing and emits low nox [nitrogen oxide, which is emitted by all boilers].'. Very good tips i am going to try them right away god bless. The boiler engineer ltd is located near ashford kent offering new installations,.