High Efficiency Furnace in Ventilated Attic
Hello! I have an american standard high efficiency direct vent condensating furnace. It is installed in an uninsulated, ventilated attic (the floor of the attic is heavily insulated, but the roof is not), though it shouldn’t have been…
Recently, there’s been a leak from the furnace (drain pan has water in it, ceiling of second floor (right below furnace) is damaged. I had two HVAC techs come to the house and say that the furnace is likely damaged because condensate froze in the winter. They recommended sealing my attic with insulation and then replacing the furnace or using a lower efficiency furnace (which I’d prefer not to do). I live in the boston area.
Reading the installation guide for my furnace, it says “the condensate drain should be installed with provisions to prevent winter freeze-up of the condensate drain line. Frozen condensate will block drains, resulting in furnace shutdown. If the drain line cannot be installed in a conditions space, then UL listed heat tape should be applied as required to prevent freezing. The heat tape should be rated at 5 or 6 watts per foot at 120 volts.” This seems to imply that heat tape would be enough to prevent future damage (and prevent me from paying to insulate the attic, which I’ve gotten quotes for at about $8k). Right now there is only foam (pool-noodle) insulation around the condensation drain and both techs told me that probably wasn’t enough, which caused the condensation to freeze and crack my drain pain / furnace so that it leaks.
My questions are
1. Would heat tape (eg https://smile.amazon.com/Freeze-Protection-Cable-Heavy-Duty-Self-Regulating/dp/B079MBXQSG/ref=cm_cr_arp_d_product_top?ie=UTF8) on the condensation pipe be enough to prevent freezing (without insulating the attic)?
2. Is it normal for a drain pan to have water in it at all? One of the HVAC techs said no and pushed a complete replacement of the furnace in addition to the insulation. The other HVAC tech suggested I could just replace the drain pan after insulating the attic.
I’d also love to hear any other thoughts.
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