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Check The Condensate Pipe When Purchasing A Home With A High-Efficiency Furnace

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When purchasing a new home that has a high-efficiency furnace, it is important to inspect the heater's condensate pipe. The drain line rarely causes issues in spring and summer, which are the busiest home-selling seasons according to Economists' Outlook's data, but it can freeze in winter and cause the home's heater to malfunction. If you're about to buy a home that has a high-efficiency furnace, here's how to check its condensate pipe so that you don't have a frozen drain and failed heater next winter.

The Condensate Pipe

High-efficiency furnaces have a condensate pipe to drain moisture that collects in the furnace. These furnaces are so efficient that excess water condenses into droplets as they extract heat from their fuel source. The drops flow down rubber hoses and into a water trap. When the trap becomes full, a condensate pump pumps the water out through the condensate pipe.

Where the condensate pipe directs water depends on whether a drain is near the furnace. If there is a drain close to the furnace, even if it's a sink or toilet drain, then the condensate pipe might be set up to carry water to this drain. The water, in this case, would then leave the home through the drain, and the pipe would never have to go outside.

If the furnace isn't near a drain, then the condensate line might carry the furnace's excess water directly outside through an exterior wall. In this setup, part of the condensate pipe is outside, exposed and liable to freeze during winter. A frozen pipe will cause a backup of water within the furnace, and the heater will eventually shut down until water can drain properly. When left unaddressed, this can cause serious issues that require a professional heater repair service.

The first thing to check is whether the condensate pipe of the home you're considering buying goes outside. If it connects to an interior drain, then there is no risk of it freezing. As long as the line remains inside, it's protected by the home's heat.  If it goes outside, however, you'll want to know how to deal with a frozen pipe and how to reduce the risk of it freezing.

Thawing a Frozen Pipe

Should the condensate pipe freeze, you will probably be able to thaw it without calling a professional heater repair service. It can be thawed by:

  • wrapping the pipe in warm towels
  • pouring warm water over the affected area
  • placing heat tape around the pipe

The last solution, encasing the exterior pipe in heat tape, would require an outlet nearby for the tape to be plugged into.

Preventing a Frozen Pipe

The risk of freezing can also be greatly reduced by designing the condensate pipe to withstand cold temperatures. When inspecting a home's pipe, check to see whether it's:

  • vertical
  • oversized
  • insulated

A vertical exterior pipe will drain quicker than a horizontal, or even a diagonal, one, so water will have less time to freeze in the pipe.

Should ice begin to accumulate in the pipe, an oversized one will provide extra room for new water to drain around the ice. The exterior line should at least be as large as the manufacturer's recommended diameter, although it may be wider. The seller ought to have a copy of the furnace's owners manual that will list the recommended minimum width.

Finally, insulation reduces the risk of freezing, but it can also be a sign that the current homeowners dealt with a frozen condensate pipe in past years. You should ask them why there is insulation on the pipe and whether they've ever had issues.

If you're about to purchase a home that has a high-efficiency furnace, take a few minutes to check the heater's condensate pipe before closing. It's easy to inspect, and looking it over could save you headaches when cold weather comes.


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