Preserve the useful detail
Build a simultaneous-use profile and map fuel, electrical, vent, drain, water conditions, location, access, and the current complaint.
The decision on display
Do not transfer the hazard
Do not promise instant hot water, unlimited flow, or savings without exact model and use evidence.
Make the proposed work comparable
Compare capacity basis, equipment, relocation, gas or power changes, venting, condensate, controls, permit, commissioning, maintenance, and warranty.
CURRENT PRIMARY SOURCE