Causes of Ice Formation on Furnace Vents

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Most property owners are, now more than ever, intent on lowering their energy expenses. Most have ditched appliances considered energy-inefficient for newer ones that use less energy. This has seen most properties now using high-efficiency furnaces. A high-efficiency furnace has an AFUE {annual fuel utilization efficiency} of over 90% compared to the 56-70% in older furnaces. The AFUE rating denotes the amount of energy being converted to heat. A score of 90% means that your furnace is converting 90% of energy and losing only 10%.

Investing in a high-efficiency furnace does not negate a furnace service in Herriman. You still need regular servicing to keep your furnace in top shape and saving as much energy as it should. One of the elements most furnace owners contend with is the formation of ice on their vents. This is because the air released from high-efficiency furnaces condenses quickly and often freezes before leaving the vents. Ice formation is mainly a consequence of installation deficiencies rather than a normal evaporation-condensation process.

Here are some of these installation deficiencies:

Improper vent pipe slope

High-efficiency furnaces require the discharging of air to the outdoors. Your vent pipe should be appropriately sloped to guarantee the air does not flow back to the furnace. Most manufacturers recommend a minimum slope of ¼’’ per foot. Some of the modern furnaces have a condensate pipe that discharges the water in your vent pipe to a floor drain rather than the outdoors.

Sagging vent pipes

Your exhaust and intake pipes should be adequately supported from the furnace to the discharge points. Your pipe’s diameter will determine the appropriate supports for it. In general, 2’’ pipe runs should have support hangers installed after every 4,’’ and 3’’ pipes should have the hangers installed after every 5’’. Without these hangers, the vent pipes will sag, and condensate will form on the sagging sections. This, in turn, restricts airflow and creates a liquid pool that contributes to the accumulation of ice on vents.

Long vent pipe runs


When your vent pipe is too long, exhaust gases from your furnace might not be pushed far enough from your property. This is because the long runs allow the gases to cool before exiting your indoors. This consequently hastens the freezing of your exhaust gases outdoors and leads to the formation of ice on your vents.

Too many pipe elbows

Most people do not appreciate the impact that 90- and 45-degree elbows have on their furnace’s operation. Each bend in your pipe run will add some restriction that a blower should overcome. This causes the blower to work too hard and increases your energy costs. Moreover, the elbows form places where condensate can accumulate and increase the risk of ice formation along the vents.

Most property owners assume that installing their furnaces is easy, provided they follow manufacturer instructions. This is the primary reason for the above installation deficiencies that cause the formation of ice on vents. The icy vents lead to carbon monoxide accumulation in your interiors and make your indoors cold and uncomfortable. Professional furnace installation is your best chance of avoiding these installation deficiencies.

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