Direct answerGenerator size starts with finished room volume.
What to check first
Glass and stone increase the heat load.
The existing pool, property access and equipment condition can change the answer. Record what is happening before adjustments are made.
What affects the work
Keep the generator in a dry service area.
A clear scope should separate inspection, repair and optional improvement work. This makes quotations easier to compare.
When a site visit is useful
A site visit is needed when the answer depends on pipework, water loss, structural movement or the exact equipment installed. Photos can narrow the likely cause but cannot confirm a concealed fault.