PENN System 550 C550A Control Modules to Provide Functional Replacements for System 350

Penn System C550ACN relay control modules and C550AQN analog control modules are functional replacements for legacy System 350. A guided setup allows users to easily configure the new module to match the one being replaced. Cloud connectivity provides two-way communication between System 550 control modules to provide alerts and warnings of potential system related issues and to facilitate troubleshooting.
Sept. 19, 2025
3 min read
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Johnson Controls announced the launch of new PENN System 550 C550A web-enabled control modules designed to streamline the transition from analog to digital temperature, humidity, and/or pressure sensing within commercial HVACR equipment. System 550 C550A is an easy-to-configure functional replacement for legacy System 350.

PENN System 550 C550A control modules support one temperature, humidity, or pressure sensor input and serve as functional replacements for System 350 A350 (temperature), P352 (pressure) and W351 (humidity) control modules, which were recently discontinued. C550A control modules feature a guided setup that allows users to easily configure the device to match the System 350 control module being replaced. 

All C550 control modules (C550C and C550A series) provide two-way remote connectivity with an annual subscription to the Johnson Controls optional Controls System Cloud. On-board Wi-Fi connectivity allows authorized users to remotely monitor HVACR system health via the PENN Controls System Cloud. Backed by Johnson Controls' service expertise, when an issue is detected, cloud-based connectivity can automatically notify a technician via email or text to help expedite service and maximize uptime. This capability is amplified by Johnson Controls' field leadership, anchored by a global network of service technicians with deep technical knowledge in building systems.

A full-character, LCD display screen enhances ease-of-use and offers customized sensor and output naming to simplify maintenance and serviceability. 

C550A control modules come in two output types: 

  • The C550ACN control module features two relay outputs and is a functional replacement for System 350 control modules with a relay output (e.g., A350A, A350B, A350E, P352A and W351A series). C550SCN relay expansion and C550SQN analog expansion modules can be added to the C550ACN control module, providing up to ten outputs (relay and analog).
  • The C550AQN control module features two analog outputs and is a functional replacement for System 350 control modules with an analog output (e.g., A350P, P352P and W351P). If more than two analog outputs are needed, customers will need to use the C550CQN series analog control module.

System 550 modules are not backwards compatible with System 350 modules. All System 350 modules must be replaced with the required System 550 module. By transitioning to new C550A control modules, OEMs can increase sensing outputs, including A2L refrigerant leak detection, using fewer modules than legacy systems have typically allowed. This can result in cost reductions and space savings within equipment designs. The C550A supports hundreds of applications, with the most popular being heating and/or cooling control, staged boiler or chiller control, boiler and chiller loop water temperature rest control, humidification and dehumidification control and combination temperature and humidity control. 

To learn more, visit: www.penncontrols.com.