Location of thermostat bulb for gas fireplace

I recently purchased a new gas fireplace (Hearthrite) with a mechanical control. It has a thermostat control valve (SIT 545) with a remote thermostat bulb. The bulb is just sort of sitting in the bottom of the unit underneath the firebox, but that does not seem like a useful location to me. The manual has no info about setting up this thermostat.
The bulb has a copper connection (tube? wire?) that is about 48" long. As received, it is just coiled up at the bottom. It seems to me that this should be located outside the box where it can measure the room's ambient air temperature.
Do I understand the principle of operation correctly? Anybody have any experience or advice about where to locate this thermostat bulb?
Rick

 

The copper wire and bulb are filled with a light weight hydraulic oil that expand when heated. As the oil expands it fills the bulb and applies pressure to a diaphragm in the gas valve. This will slowly reduce the overall amount of gas flowing through the valve. As the room cools so does the oil which retracts back into the bulb.
The typical location to mount the bulb is in a bracket on the bottom of the stove. As the stove gets warm air circulation is created which causes airflow under the stove. This airflow will heat or cool the oil resulting in a demand for more gas to heat or reduce the gas flow as the desired temperature is reached.

 

Thanks much for the explanation as well as the recommendation for location. It helps to clear up my confusion. It also explains why the bulb was sitting where it was from the manufacturer with no explanation as to where else to put it; it's already in the right place. I'll make sure it is seeing the airflow coming in from the bottom front.
Rick