CSA 4.1-2017 Gas water heaters, volume I, storage water heaters with input ratings of 75,000 Btu per hour or less.
The general construction and assembly of the water heater shall be of a neat and quality manufacturer with parts well fitted and bolts or other fasteners drawn up tightly to give rigidity. Any exposed edges that might reasonably be brought in contact with the hand during servicing and usage shall be smooth.
Asbestos shall not be used in the construction of a water heater.
An opening of sufficient size to permit ready access for cleaning the burner compartment shall be provided in the water heater casing. If satisfactory means for cleaning the burner compartment can be demonstrated, with the water heater installed as it would be in service, this requirement shall be deemed met.
Adequate means shall be provided to prevent products of combustion or condensation from the products of combustion from coming in contact with insulating material above the burner port level, unless the manufacturer submits evidence to the testing agency that the material used is satisfactory for the conditions to which it may be subjected. This provision shall not be construed to apply to the use of reasonable tolerances for assembly.
The means of flame adjustment shall be secure so the adjustment cannot be changed unintentionally.
A water heater of the other than direct vent type, either shall comply with Test Condition A and B as specified in Clause 5.16, Wall, floor, and ceiling temperatures, or shall be designed or equipped with a manual reset or single use device or control system, or equivalent means, to shut off main burner gas to the water heater in the event the flow of combustion products through the water heater flue-way(s) is reduced when tested as specified in Clause 5.10, Heat roll out safety shutoff means.
A direct vent water heater shall be provided with the vent-air intake system as part of the appliance.
Vent-air intake systems shall be provided with means for secure attachment to the appliance or wall
Storage vessels shall be equipped with a drain valve to facilitate emptying the tank for cleaning or withdrawing small quantities of water to eliminate foreign deposits. Drain valves on counter-type water heaters shall be accessible from the front of the appliance.
Drain valves and temperature limiting devices on water heaters certified for closet installation shall be accessible, with the water heater installed as it would be in use or service.CSA 4.1 pdf download.