You should check with your local building inspector to see what type of licensing is required for pool heater installation. If your state requires pool heater installation contractors to be licensed, then you could be left without any legal recourse if the job is done poorly. Licensing is also a way for local governments to ensure citizens aren't being fleeced by unscrupulous contractors.

Get an estimate before you hire the contractor. This is a very straightforward job that does not provide many opportunities for problems to occur. As such, it is an easy job for a contractor to come up with an estimate for.

During the job, you should try to make sure the contractor stays close to the approximate costs of the work. If possible, try to get the contractor to put your estimate in writing so there is no confusion.