soil heaters

has anyone used a soil heater for their outdoor grow in zone 6 or colder? having an rather warm fall this year but just seeing how wonderful a single plant with no added care or cost is doing makes me want to do a full outdoor grow next year.

I seen the ones on amazon that looks like the roof deicers and pipe heat tape. maybe other types?

you can make one with some piping and compost thats the ones i have see. some use geothermal and they pipe the hot air of the summer under the greenhouse for the winter, but for that you need to ding you greenhouse in the ground under the frost level and it takes a full spring and summer to charge for the winter but will keep the greenhouse warm for cheap they have some made by canadians on youtube. it all depends on the type of heater you want to go with. i know someone here in zone 3b that works wonderful but might be over kill for zone 6