Before you choose any one to do any repairs or improvements on your plumbing, heating or cooling systems, raise your comfort level about your choice to the max by asking a few questions that all responsible contractors will be happy to answer. For example:
Will they give you a Certificate of Insurance to confirm that they have appropriate liability and workers’ compensation insurance?

Will they have all appropriate local and state licenses? (Ask for their license numbers. Plumbers must be licensed, by law.)

Will they arrange to get all required building permits?

Will they provide detailed written estimates, including provisions for handling changes?

Will they provide a contract before any work starts that specifies all the services and products to be provided with a timetable and terms of payment? (Beware of substantial upfront, down payments or requests to make your checks out to a party other than the one named on the estimate and/or contract.)

Will they give you a copy of all documents you sign for you to keep?

Will they provide a waiver of lien for themselves and any subcontractors they use? (Insist on this.)

Will they install professional-grade products that usually provide longer warranties and/or more features than standard-grade products sold at home centers?

Will they offer service or maintenance agreements – and what exactly would they cover?

Will they provide references from a large number of customers in your area for whom they’ve done similar work (you don’t want to get just their “favorites”)? Check particularly about the quality, promptness, cleanliness and overall professionalism of the service and products provided. And check out your local Better Business Bureau to see if any complaints have been filed.

All this may seem tedious and time consuming. But your family’s health, safety and comfort are involved as is your convenience and money – so check out tradesmen you may hire to be sure they’re professional and not just part-time handymen. You’ll be greatly increasing your odds for a pleasing experience.