I think I may have posted earlier, use a chicken (IR) lamp pointed at the HST case. It heats the CASE, not the air and there's a LOT of internals that need to get well above 40 to get the watery oil to flow. Seriously you could have ice dams ( blockages ) , so lower 'oil' melts a bit, flows out, but NOT stuff up higher. You'll be very lucky IF after a week of 40F temp ,most has drained out. If it gets cold(32) at night, it all freezes again.....arrrrrghhhhhhhh