Roof Heaters On: 2009-12-08
11:40 PM: Turned on our roof heaters tonight, as around four to six inches of snow have fallen. With that much accumulation on the roof, I want to make sure we get minimal ice build-up in the gutters. This can result from that snow melting on the warm roof surface, running to the edge of the roof where it’s cold, dripping into the gutters, and then freezing solid. When this happens, the gutters become clogged with ice, and therefore are no longer effective at carrying the melting snow away. So, any water subsequently flowing off the roof gets dammed at the roof’s edge, when it hits this gutter ice, and then it flows back up the underside of the roof, which is actually inside our attic.
Such build-up has, in past years, caused water damage to the interior ceilings on the first floor below. Needless to say, I’m therefore hyper-vigilant, perhaps even anal, when it snows. Thus, when snow falls, I quickly activate those heaters when the temperature reads between fifteen and thirty-two degrees. Above thirty-two, roof runoff won’t freeze before it reaches the ground through the gutters. So when it’s balmy, the heaters aren’t needed.
The same is true at the other extreme, but for a different reason. When the temperature falls below fifteen degrees, the heaters do not generate enough BTUs to melt any accumulated ice and snow. Plus, when it’s this cold, we don’t get much roof runoff, as the heat escaping to the roof from inside the house is not enough to melt the snow on the outside. So, since there’s no appreciable runoff at sub-fifteen-degree temperatures, there’s thus, no water to freeze up and clog the gutters. But even if there was runoff, the heaters are not hot enough to keep it from freezing. Therefore, running the heaters under these conditions would do little good, and cost lots of money besides.
Our heaters draw 16 amps at 120 volts, which is roughly 1920 watts of power. At roughly ten cents per kilowatt hour, this means that we pay around twenty cents per hour to keep the gutters warm. This can add up at $4.80 per day. So let’s put it this way: You don’t want to forget that you have these things energized, lest you find later that your wallet is empty after paying your high electricity bill.
They make automatic switches that turn on and off the heaters based on temperature and the presence of water in the gutters. But as of yet, I’ve not purchased them. The are a little costly and require some labor to install. Besides, I like that the house “needs me” to care for it, by manually turning on and off the heaters. 