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White rectangular thermostat with mechanical dial and terminal labels

Emerson Climate Technologies

Emerson Climate Technologies 1C21-101 Mechanical Cool Only Thermostat 24VAC

SKU CH-A4YS-DMQPW

A mechanical cool-only thermostat with a 50 to 90 degree Fahrenheit range, hardwired for 24 VAC systems and mercury-free

  • ColorWhite
  • Cool-only control for simple AC systems
  • Mercury-free mechanical operation for reliability
  • Hardwired 24 VAC power eliminates batteries
  • Vertical mount fits standard wall boxes
  • 50 °F to 90 °F range covers typical cooling needs

Mechanical Cool-Only Thermostat 24VAC

This Emerson mechanical thermostat provides simple cooling control for residential and light-commercial HVAC systems. It operates on 24 VAC hardwired power and suits gas or oil equipment where a basic temperature dial is preferred.

Vertical Mount Hardwired Installation

The unit mounts vertically and connects via R and Y terminals with no system or fan switching options. Installation is straightforward for experienced technicians, but the lack of automatic changeover and dual-transformer support limits flexibility in multi-stage setups.

Compatibility Check Before Ordering

Verify your system runs on 24 VAC and requires only a single cooling stage with no fan control. Confirm the 50 to 90 degrees Fahrenheit control range matches your application and that vertical mounting fits the chosen location.

Highlights

  • Cool-only control for simple AC systems
  • Mercury-free mechanical operation for reliability
  • Hardwired 24 VAC power eliminates batteries
  • Vertical mount fits standard wall boxes
  • 50 °F to 90 °F range covers typical cooling needs

Specifications

BrandEmerson
ColorWhite

Questions about this item

How do I verify the 1C21-101 is controlling my cooling system correctly after wiring it to the R and Y terminals?

Set the dial to a temperature below the current room reading; the compressor should start. Raise the dial above room temperature; the compressor should stop. The mercury-free mechanism clicks at each changeover.

What comes in the box with the Emerson 1C21-101 and what must I supply separately?

The thermostat body and mounting hardware are included. You must provide 24 VAC control wiring, wire connectors, and a screwdriver for the hardwired terminal block.

Which Emerson 1C21-101 version should I choose for a single-stage gas or oil cooling system?

The 1C21-101 is a single-model mechanical cool-only thermostat rated 30 VAC with a 50 to 90 °F range; no alternate versions or capacities are offered for this part number.

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