How to identify which Ranco ETC model you have:

The model number of the Ranco ETC controller is normally on a small sticker located on the back of the controller.  This makes it difficult to determine which model you may have when it is mounted.  There may also be another sticker with the first four digits of the model number on a sticker on the left side of the stage one relay (#3 in the picture at the bottom of this article).

Fortunately it is fairly easy to determine which model you have a visual inspection under the cover.   Disconnect the power from the unit to prevent electric shock and remove the 4 screws and lift off the faceplate.

Instructions

From the pictures below, determine which features your controller has, mark them off on the following chart, and you'll determine which Ranco ETC model you have.

Single or Two Stage:
The single stage models only have one terminal block. Models: ETC-111000-000, ETC-111100-000, ETC-112000-000, ETC-112100-000, and ETC-141000-000	The two stage models have two terminal blocks near the bottom of the controller.  Models: ETC-211000-000, ETC-21111000-000, ETC-212000-000, ETC-212100-000, and ETC-241000-000
120/240V or 24V
The 120/240V models have a transformer in the middle of the circuit board with a terminal block just under it labeled 240/120/COM.  Models: ETC-111000-000, ETC-111100-000, ETC-211000-000, ETC-210100-000, ETC-141000-000, and ETC-241000-000	24 volt models do not have a transformer and have a single terminal block labeled 24/COM in it's place:  Models: ETC-112000-000, ETC-112100-000, ETC-212000-000, and ETC-212100-000
Models with 0-10 Volt Output
Models with 0-10 volt output have a terminal block in the upper right hand corner of the circuit board (left), and an extra hole in the right side of the case. Models: ETC-111100-000, ETC-211100-000, ETC-112100-000 and ETC-212000-000.
NEMA-4 Models Finally, Nema-4 models will have an exterior flange for mounting the control on the top and bottom sides of the case as well as a water tight strain relief where the sensor exits the control.  Models: ETC-141000-000 and ETC-241000-000.

Inside the Ranco ETC (the short version):

To the right is a picture of the inside of the single stage, 120/240 volt model ETC-111000-000.  The various parts are labeled and described below.  Not all parts exist in all models and by determining which parts your controller has, you can determine which model you have.

1. Stage 1 Terminal block.  This is visible in all models.
2. Stage 2 Terminal block.  Only visible in 2 stage models.
3. Stage 1 Relay.  Visible in all models.
4. Stage 2 Relay.  Only exists in 2 stage models.
5. 120/240V terminal.  Only visible in 120/240V models.
6. Transformer.  Only visible in 120/240V models.  If you have a 24volt model a terminal block will be located here in stead.
7. 0-10V output terminal block.  Only exists in models with the 0-10V output option.