Explain the problem or project you want addressed and ask how the company assesses it.
Ask who is responsible for the installation and who handles service afterward. Confirm credentials relevant to the proposed work with the issuing jurisdiction, and ask the company for current insurance evidence.
A recognizable brand or advertised offer does not replace a proposal specific to your house.
Compare the assessment before the equipment
Ask each bidder how heating and cooling capacity was determined, what airflow was measured, and which parts of the existing system remain. Two proposals with different model numbers may be solving different problems. A useful comparison starts by reconciling those assumptions.
For installation work, request indoor and outdoor model numbers, AHRI-rated combinations where relevant, electrical work, drain and line-set work, duct modifications, controls, permits, startup testing, exclusions, payment schedule, and service responsibility. Ask whether subcontractors will perform any part of the scope.
Verify claims at their source
Start with the source page and check date shown on each directory record. Confirm that the company still serves your address and offers the type of work you selected, then ask who will perform the installation and service it afterward. A directory listing does not confirm appointment availability or the terms of your project.
The company websites cited here document services those companies advertise. They do not verify licensing, insurance or project quality. For work in Denver, use the city’s contractor-license guidance to identify the credential relevant to the proposed work and confirm it with the issuing jurisdiction.