This specific sizing is determined by the furnace's BTU rating and the type of gas used (Natural Gas vs

12" insertion length to monitor internal plenum temperatures effectively

ensuring a secure connection to the control module

Is the AT-505 suitable for both pneumatic and electronic controls

Carrier HH18HV131 Limit Switch This specific sizing is determinedThe Carrier HH18HV131 Limit Switch is a critical OEM replacement part designed for precise thermal regulation in Carrier, Bryant, and Payne HVAC systems. Engineered as a high limit safety device, this automatic reset switch features a 130 30 degree operating range, meaning it trips at 130F to prevent furnace overheating and automatically resets when temperatures drop by 30F. Reliable thermal protection is essential for preventing damage to the heat