As energy codes get tougher, one thing that is changing in many markets is furnace efficiency. HIgher efficiency units, such as 90% efficient gas furnaces, are becoming more common in places where they're not a familiar item. And as with any new technology, the new equipment brings new problems.

In North Carolina, last winter brought a rash of reports of furnace trouble. In particular, homeowners reported that condensate lines from the furnaces were freezing up during cold snaps — and when condensate can't drain from a high-efficiency unit, the furnace eventually "locks out" and stops working. That means no heat for the homeowners. With winter approaching, some North Carolina residents are wondering whether they'll be ready for cold weather this winter.

Here's the background from Raleigh-Durham TV station WRAL. Last April, the station reported that some homeowners in the Raleigh market were experiencing ice-up and lock-out in their new furnaces (see: "Homeowners find green heating units can't take the cold," by Monica Laliberte). "Chatham County Chief Building Inspector Tim Sawyer ... said a side effect of all brands of high-efficiency furnaces is increased condensation which can freeze when temperatures drop," the station reported. "Homeowners from Atlanta to New Jersey have posted similar complaints online." Builders in the area were advising homeowners to pour hot water on the frozen condensate drains, wrap them in blankets, or re-route the drains into a bucket and empty it by hand — all solutions with obvious drawbacks.

Unfortunately, North Carolina plumbing codes, and some local ordinances, didn't allow the obvious fix: draining furnace condensate into ordinary plumbing drains. But state lawmakers quickly got on the case, WRAL reported in July (see: "State lawmakers move to change code for 'green' furnaces," by Monica Laliberte). "Dan Tingen, chairman of the North Carolina Building Code Council, said it is a case of the code not keeping up with new technology, and he promised a change," the station reported. "State lawmakers are considering a measure that would allow the dripping to be fed into other pipes in the house, like the laundry or wastewater collection system."

State lawmakers passed the change, but some local wastewater utility managers are concerned with adding furnace condensate drainage to their existing wastewater load, the station reported (see: "'Green' furnace law still needs tweaking, some say," by Monica Laliberte). "A change in the state law ... allows condensate, or dripping water from energy-efficient furnaces, to be rerouted to a home's sewer lines," the station reported. But the station noted concerns expressed by Raleigh Public Utilities Department official TJ Lynch, who said "What I don't like about the new law is that we're being forced to take on a water, a discharge, that doesn't need to be treated." 

Instead, Lynch and other local utility officials are pushing state code officials to consider another option: requiring the condensate drain to the outside, but provide a T in the line that would allow the fluid to drain into the home's wastewater line only if the drain to the outdoors was blocked. That would let the furnace keep working during freezing outdoor weather, but allow condensate to drain to the outdoor environment whenever the outdoor drain was open, reducing any added load for wastewater utilities.