An expansion loop is a U-shaped or S-shaped pipe section that absorbs the lengthening and contraction of piping as water temperature changes. These loops are critical in hydronic heating systems where pipes experience significant thermal expansion.
Technical Details
Copper pipe expands approximately 0.0094 inches per foot per 100 degrees Fahrenheit of temperature change. A 100-foot copper line experiences 9.4 inches of expansion when heated from 50°F to 150°F. Expansion loops are sized to handle this movement without stressing joints or equipment connections. Loop diameter and bend radius depend on pipe size and expected temperature swing. Standard loops use 90-degree bends with a minimum bend radius of 5 pipe diameters.
Applications
Expansion loops prevent pipe stress and joint failures in long hydronic runs. They redirect thermal movement away from equipment connections and wall penetrations.
Practical Significance
Properly designed loops eliminate the need for expansion joints and reduce maintenance costs. They accommodate up to 2 inches of pipe movement without damage.