A temp control is a must have for brewing in my house, even this time of year I couldn’t keep the fermenter under 73 without one.
I have a real old school t-stat from the 70’s that I put together, works like a champ, I’ll take some pics and post them its pretty sweet and didn’t cost me a dime.
A note about temp probes, never directly submerge them; always use a well. Even “submergible” probes will go bad eventually because of water contact. Use a well into a water bottle and your probe will be working worry free.
I had a “submersible” probe go out on me and caused my beer to freeze, not fun.