Fermentation heaters

it got colder in my basement the last couple of days - enough so that I need to start thinking about a heater for my 7 cu ft chest freezer where my primary fermentation takes place. I've looked at those wrap-around-the-carboy units and it seems those may be susceptible to being easily damaged - don't much care for electric shock or fire hazards so I'll likely look elsewhere.

I have a small heating pad in there right now hooked up to my Johnson controller but it is a meager 45W - likely not enough to carry me through the winter months (no HVAC in basement yet).

There was a stick-on heater designed for chest freezers I saw once, about a square foot or so - 110 V, can't remember where I saw it, but I was wondering if that approach would be better/safer for heating the fermentation chamber when needed. Anyone use these devices and if so, do you have any advice for me?

Hey Phil-

I use the 45W wally world heating pads.  I can maintain beer temps up to 15F above the fridge temperature.  If I need to go higher than that, I use reflectix to jacket the fermenter.  That gets me up to about 25F above the fridge. 

Thanks Tom, good to know. Do you just drop them in somewhere not in contact with the carboy(s) as I have done (I only have one in there right now)? And do you use more than one?