Coal Trol Not Reading True Room Temp

I recently purchased a coal trol thermostat setup for my Reading Juniata stove. I just hooked it all up today. I also have 2 atomic clocks in my house. Both clocks currently read the inside temperature is about 67-68F degrees. My coal trol is only showing 55F.

Is this a faulty unit?

Also the coal trol thermostat is in dining room, and one of the clocks is in the same room.

I have checked mine and it is within 1 degree so I don't know.

There is a way to adjust/calibrate that. Were you in the advanced menu? TB should be around 130.

I have not been in the advanced menu. It doesn't mention any advanced menu in my manual either.

You can do some calibration with it, but 12-15 degrees is going to be out of range or right at the edge of out of range. Will you please call our shop to discuss this, kbrindle? 315-299-3589. It does sound like you got a faulty unit, but some things we'd want to check first:

1) Is this mounted on an interior wall, not an exterior facing wall?
2) Is it mounted near a window or other place where it is in a cold draft?

While I said you may be out of range for fully calibrating with that much discrepency, you can try:

As for calibration, if you press and hold the menu button for 15 seconds or so, it will show a screen that alternates between R and A with a temperature displayed. R is the "raw" temp reading and A is the "adjusted" reading. If you press up and down buttons on this screen it will go to "TB ###" the number is a bias adjustment value. Higher values will lower the adjusted temperature, lower values will increase the adjusted temperature, roughly 7 points per degree if I remember right.

Before modifying the TB setting please write down the value it shipped with so you can revert back if needed.

If you can calibrate it to where you want it and you find the unit works otherwise (which is entirely possible, the thermistor you got may be out of normal tolerance, but the rest of the unit is perfectly fine) you can run with it that way and maybe wait until after the heating season to send it in for replacement of that one part under warranty.

Two years ago when I first started my coal stove I just hung the Coaltrol from a nail on the wall. Needless to say it wasn't plumb and level. I kind of remember getting inaccurate temperature readings until I finally mounted it correctly. I'm not sure if being level actually makes a difference on a Coaltrol? I just thought I would mention this.

Level does matter too. There is small hole on the top and bottom edge on the left side which will allow air to move through and out the unit, driven by the heat the thermostat electronic generate like a chimney. If the unit is not mounted to a wall in a normal way it can interfere with that air flow and cause unreliable readings. Can't be sitting on a shelf or counter. Can't be laying on its back on the top cushion of a couch. etc.

However, normally a bad mounting situation will lead to it reading higher temps than it should. In this case it sounds like it is reading significantly below expected temp which does lend credence to the idea that there is a faulty component in the thermostat.

The usual reason a thermostat is reading significantly under temp compared to another in the room is because one of them is mounted on an exterior wall or near a drafty window/door, resulting in significant temp difference between the units. This is why we (and other thermostat makers) recommend mounting on an interior wall, out of the path of direct sunlight, drafts, or other causes of localized temperature difference compared to the room at large.