Expansion tank holds up to how many gallons?

• A. 5 gallons
• B. 15 gallons
• C. 10 gallons
• D. 20 gallons

Answer: (C)

Expansion tanks absorb the extra volume water takes up when heated in a closed piping system, preventing pressure from rising and protecting components like pumps and valves. In many standard setups covered by these questions, a ten-gallon tank provides enough empty space to accommodate typical thermal expansion without overdesigning the system. A much smaller tank would fill quickly as water expands, risking higher pressures or more frequent relief actions. A much larger tank would be unnecessary for the usual installations described and would add cost and space without added benefit. So, ten gallons is the capacity used for this scenario.