This past February when the 'polar vortex' went through Arkansas, we lost about two-thirds of our collection. Some of the orchids we were growing were with us over twenty years and many were gifts or purchases of mature plants that had been divided back in the early 90's. The heater in the greenhouse failed because of the thermal coupler. Once that quit working the heater stopped. The pipes in the greenhouse that ran along the inside walls froze and split open showering a great portion of our slipper orchids. When I found the problem it was at least a day later in -8 degree temperatures. The water had formed an ice sculpture where it was 'misting' out of the broken pipe. The ice covered the entire end of the greenhouse and kool-cell. It was horribly -- beautiful. We were completely shocked as we have an exterior alarm system that is temperature controlled. The thing is - we didn't remember to switch it to "winter" at the end of the 'Summer' season. Long story short - a system like you got above sounds like a sound investment. Anything that takes human error out of the equation.
At the end of the summer I was still removing dead, frozen plants. Good news is that when it came time (Friday) to move my tropical plants in from the deck before the first frost, I had plenty of space in the greenhouse this year. LOL. Let us know how the system works as it gets colder, Ray. This sounds like something I need to start saving up for before it gets too cold here. (BTW - I remembered to flip the switch on the alarm to 'Winter' when we lit the pilot light on Friday. Now let's hope the heater keeps working.)