Look for physical indicators such as a bulged top

For HVACR technicians performing field replacements

For sealed combustion furnaces

a clogged or missing AT-529 restrictor is often the culprit

you can almost always upgrade to a 40VA unit to provide more stable power for additional low-voltage accessories

Honeywell 204480 Fitting Look for physical indicators suchThe Honeywell 204480 is a specialized 5 16" regulator vent pipe fitting engineered for seamless integration with industrial and residential gas valves. Designed specifically for use with the V4843 and V8843 series, as well as V4943 models, this high grade fitting ensures precise atmospheric venting for gas pressure regulators. As a veteran preferred HVAC replacement part, the 204480 provides a secure, leak resistant connection critical for maintaining