Hi Eric
 
Check with and electrical wholesaler for a thermostat.  They have some that are
rated for 110 volts and 220 volts and are adjustable. Normal household
thermostats are rated at 24 volts so don't use that type.  Just call the
wholesaler or electrical supply house in your area and tell them what you want
to do. If they won't sell directly to you, they will tell you where you can buy
one.
 
Frank Humphrey