I'm trying to replace my old thermostate that had 120v wire connected to it. It has a hot to R terminal, a hot to a C terminal and a 30v to the B terminal. I'm trying to replace it with a honeywell rlv430 thermostate. Please help. I'm living in a condo and I believe it uses a chiller. Above my ceiling there is two hot water pipes going to the unit itself.

The thermostat you have will not work.

http://customer.honeywell.com/techlit/pdf/69-0000s/69-1855.pdf

What is the exact brand and model number of the old thermostat. You have a combined system style thermostat and kind of rare.