That is exactly what i have done for the most part. Just check to be sure the wattage you are running through the primary can be handled by the secondary. I have the primary set to 92ºF and the secondary set to 98º so if the prime fails 'open' when the heat hits 98º (on the flexwatt the enclosures in my case take 2º so inside 90 and max would be 94 the heat comes on very fast if it runs away...) the secondary shuts the power off period. I have had a herpstat fail (Dion has been great with that too BTW) it is never a bad idea to have a back up.
This may help not the right brand but the principal will be the same.
http://www.spyderrobotics.com/suppor...edocument.html