There actually is a no-heat solution!
Refractor dew control WITHOUT heat - it is possible!
Effective, far less power requirements, and more efficient.
If you can set up in a location that has less propensity for dew even better - dew and astro are not inseparable bed fellows. Of course this depends on your situation as to whether or not a different site is a practical option or not. For me, setting up from home means dew is a frequent problem, whereas at my dark site dew is very rare - in 14 years dew has formed 6 times, with only once being heavy enough to trouble scopes. From home, I've been using fans now for pver a year with my 9" Mak & my refractors.
Fans with Maks & SCTs:
SCT & Mak total dew control without heat - a solution!
Heat is not the only solution for dew control. Professional observatories don't use heat, but fans.
Alex.