When our local water company started adding Watts No. 7 dual-check backflow preventers to all water services, we soon discovered water heaters were failing at a rapid pace, with gas fired models exhibiting telltale signs where the cold/hot water lines skewed off making them look like a bow-legged cowboy! Center flue tubes were collapsed, causing the by-products of combustion to spill out the access doors and, in many cases, melting the plastic temperature adjustment knobs. Lots of crazy remedies appeared — seemingly overnight —at our local supply houses, which included:
Who knew I was about to meet up with Boyle’s Law! Way back in the 1600s, Robert Boyle had studied the relationship between pressure and volume. Boyle’s study determined that P (pressure) x V (volume) derived a constant and the constant did not change as P and V were modified. P1 x V1 = C therefore P2 x V2 = C. That got me thinking about how to properly size a TXT for our residential water heaters to ensure no more callbacks. I no longer trusted the paperwork provided by the TXT manufacturers, and set out to build a test where the results could be documented.