What is a common component of all FVIR water tanks?

A flame arrestor-plate is a crucial safety component of all FVIR (Flame Sensing Vertical Ignition Resistance) water tanks. This component serves to prevent flames or combustion gases from escaping the combustion chamber of the water heater, effectively reducing the risk of fire hazards associated with gas water heaters.

The flame arrestor-plate works by creating a barrier that mitigates the possibility of flames reaching the outside environment. In the event of a backdraft or malfunction, this device helps to contain the flames, preventing them from igniting flammable materials nearby, which is particularly important in residential settings where water heaters are often located in utility rooms or near other combustibles.

While the other components listed, such as pressure regulators, temperature gauges, and electrical heating elements, may be found in various types of water heaters, they are not universally present in all FVIR models. The flame arrestor is specifically integral to the design and function of FVIR tanks, ensuring they operate safely. Therefore, its presence is a defining characteristic of FVIR technology, making it the correct answer for this question.