Temp at which thermostat opens ( fsi )

Have to replace my thermostat due to
Broken heating element.
I bought one second hand. Its closed, but I tried today to see if it opens.
I dipped it in a pan of boiling water ( electrical elements were outside water of course )
And nothing.. It didnt open. Does it mean its faulty or is boiling water just not enough temp to make it open?

A standard wax element thermostat normally starts to open around 85 degC but I understand the fsi stat is electronically controlled. This suggests the stat opening is regulated by the engine ECU based on signals from coolant (and possibly air intake) temperature sensors.

Cheers Spike

PS - Just found this which may be of interest - http://www.volkspage.net/technik/ssp/ssp/SSP_222.pdf

http://www.meeknet.co.uk/E38/E38_Map_Thermostat.pdf

Function of the characteristic map thermostat
The characteristic map thermostat is tuned such that it opens at a coolant temperature at the thermostat of
103oC from the engine inlet without intervention of the integrated heating facility. Due to the coolant being
heated in the engine, the temperature at the engine outlet (place of installation for the coolant temperature
sensor for DME and instrument cluster display) is approx. 110o C at this point in operation. On reaching this
engine operating temperature the characteristic map thermostat begins to open without control intervention.
In the event of control intervention by the DME control unit, power (12 V) is applied to the heating element
integrated in the thermostat. Heating the expansion element means that the thermostat opens at lower
coolant temperatures (thermostat control range: approx. 80oC - 103oC).

no wonder my thermostat did not want to open wider in boiling water. hardly 100oC
peace of mind now