OAT for Waterfurnace Series 7

[Gerthex]

Hello,

I have a Waterfurnace Series 7 (with Intellizone 2 thermostats) and am looking to install an outdoor air temperature sensor (OAT). an OAT was supposed to come with the intellizone 2 but for some reason the previous home owner/HVAC tech never installed it. 
I can find the part (TSU02) for sale but costs about 80 dollars including shipping. This seems sort of expensive to me for a thermo. Can I use a universal outdoor air temp sensor (2 wire) or do I need the Waterfurnace one? I work in a test lab using K-type thermocouples (TC's) and we generally throw out TC's when they get too short to be reused or after use. I could probably find one long enough that is being scrapped for my application, could I use a thermocouple(could even verify working condition)?

My electric heat keeps kicking on when going from night time temps (66°F) to day time temps (70°F). With an OAT this should prevent the electric heat from coming on with setting adjustments in the Intellizone 2.

Thanks all