Adjustment - PENN Controls - A19BAC - A28AA - Electromechanical Temperature Control - A19 Coiled Bulb Control - A28 and A36 Multi‐Stage Temperature Control

A19BAC, A28AA Single and Two-Stage Space Thermostats for Farm and General Purpose Applications Installation Guide

PENN Controls
Product name
A19 Coiled Bulb Control
A28 and A36 Multi‐Stage Temperature Control
Document type
Installation Guide
Part number
Document revision
Revision date

Knob adjustment or screwdriver slot is supplied on the range screw. Dial pointer is located on adjustment stop bracket on knob and screwdriver adjustment models.

Before removing the cover, verify that all power to the thermostat and associated equipment is turned off.

  • Risk of Electric Shock
  • Disconnect or isolate all power supplies before making electrical connections. More than one disconnection or isolation may be required to completely de-energize equipment. Contact with components carrying hazardous voltage can cause electric shock and may result in severe personal injury or death.
  • Risque de décharge électrique
  • Débrancher ou isoler toute alimentation avant de réaliser un branchement électrique. Plusieurs isolations et débranchements sont peut-être nécessaires pour -couper entièrement l'alimentation de l'équipement. Tout contact avec des composants conducteurs de tensions dangereuses risque d'entraîner une décharge électrique et de provoquer des blessures graves, voire mortelles.

Solid cover models are adjusted by removing cover and moving dial so that the setpoint is in line with the dial pointer on the stop bracket. (See Figure 1.)

Convertible adjustment models can be field converted from concealed screwdriver slot adjustment to knob adjustment or external screwdriver slot adjustment. They are supplied with a snap-in plug in the cover to provide concealed screwdriver slot adjustment. For knob adjustment remove the snap-in plug and press the knob onto the slotted shaft. For external screwdriver slot adjustment remove the snap-in plug.

The A28AA switch is stamped to indicate the HI-TEMP switch and the LO-TEMP switch.

The Space Thermostats with convertible adjustment have a snap-in plug in the cover, built-in screwdriver slot and a knob for field installation.

Figure 1. Space Thermostat with convertible adjustment

A high temperature adjustment stop is supplied on the thermostats. (See Figure 1.) If adjustment stop is required:

  1. Set dial to temperature at which stop is desired.
  2. Remove cover from thermostat.
  3. Loosen the adjustment stop screw, slide the screw to the front of the thermostat against the plastic stop cam behind the dial and tighten the screw.(See Figure 1.) Sometimes an exact stop setting is not possible and stop must be set to the closest step corresponding to dial setting required.
  4. Turn dial to setpoint desired.
  5. Replace cover.