Methods of making a fuel-fired heating appliance

A method of fabricating and testing a fuel-fired heating appliance having a side wall portion with an opening therein, and a combustion chamber opening outwardly through said opening, said method comprising the steps of:

• providing an access door/burner assembly including an access door member having a burner lighting and test opening therein, main and pilot fuel supply tubes sealingly extending through and anchored to said access door member, and main and pilot fuel burners supported on said main and pilot fuel supply tubes for movement with said access door member;
• positioning said main and pilot fuel burners within said combustion chamber;
• installing said access door member on said side wall portion to cover said side wall portion opening;
• inserting a lighting structure into said combustion chamber through said burner lighting and test opening in the installed access door member;
• using the inserted lighting structure to light and test said main and pilot fuel burners;
• withdrawing the inserted lighting structure from said combustion chamber through said burner lighting and test opening;
• and
• snap-fitting a sight glass structure into said burner lighting and testing opening after said withdrawing step.