it's 28 degrees outside. my op is in an old barn insulated and sheet rocked. well it's still cold out there. even drawing in from inside i can't get my temp above 64 degrees. so i've taken my kitchen timer and set it for every 4 hours. when it goes off i go out and burn kerosene for 1/2 hour or so. get the temp to 80 then go sleep for 3 more hours. they love the co2 from the heater but i heard temp fluctuations such as this are bad. i see no ill effect and my plants sure perk up with the heat. but my head is killing me from this schedule.