Section 17-105 - Heating system efficiency tests1. For the purposes of this section: a. "Contractor" means any person who contracts to install, repair or service oil or gas heating systems for customers.b. "Oil heating system" means a device which burns either No. 2 or No. 4 fuel oil for heating purposes.c. "Gas heating system" means a device which burns either natural gas or propane for central heating purposes.d. "Service contract" means an oral or written agreement between a contractor and a customer which requires the contractor to service the customer's oil or gas heating system.e. "Customer" means any person who resides in, or is the owner of, a one, two or three-family dwelling or a single unit of a multiple dwelling, including an individual condominium unit or cooperative unit, who uses an oil or gas heating system for heating such dwelling or unit and who is responsible for the operation and maintenance of such oil or gas heating system.f. "Efficiency test" means a test of steady-state efficiency and shall include the following procedures: (1) with respect to an oil heating system, measuring the carbon monoxide, measuring the carbon dioxide or oxygen content, measuring the net stack temperature, measuring the smoke level, and such other procedures as the contractor shall deem appropriate; and (2) with respect to a gas heating system, measuring the carbon monoxide, measuring the carbon dioxide or oxygen content, measuring the net stack temperature, and such other procedures as the contractor shall deem appropriate. 2. Every contractor who offers to perform service contracts for customers shall offer to include in such contracts a yearly efficiency test. Such test, which shall be at a customer's option, shall be performed after any repairs or adjustments have been completed pursuant to the service contract, and the additional cost, if any, for such test shall be separately charged. Upon the completion of any such test, the contractor shall provide the customer with a form listing the values for carbon monoxide, carbon dioxide or oxygen content, the net stack temperature, and the smoke level, as appropriate, and the steady-state efficiency (expressed in a percentage) determined therefrom.3. The commissioner shall make reasonable efforts to notify all contractors of their obligation to offer efficiency tests to customers as provided by the provisions of this section.