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Can Condensate Leaks In High-Efficiency Gas Furnaces Damage Your Property?

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High-efficiency gas furnaces combine power and reliability with very low running costs, so it's no wonder that so many households rely on them for their heating needs. However, while high-efficiency gas furnaces have many advantages over less sophisticated heating systems, there is a price to pay.

Like conventional gas furnaces and oil furnaces, high-efficiency gas furnaces are fitted with condensate lines. These pipes direct liquid condensation created during the combustion process to your drains. 

If these lines start leaking or become clogged, the liquid can spill out of the line (or even the furnace itself) and into your property. While this can be a serious issue with any furnace, owners of high-efficiency gas furnaces should take special care to avoid condensate leaks.

Why Are Condensate Leaks Worse In High-Efficiency Gas Furnaces?

The liquid condensation flowing through your furnace's condensate line may look like regular water, but it contains a variety of chemicals and trace elements. These are byproducts left behind when your furnace burns fuel. They lower the pH of the condensate liquid, causing it to become acidic. Because high-efficiency gas furnaces recirculate exhaust gases to extract more heat, more of these chemicals make their way into the condensate line.

While the condensation produced by oil and conventional gas furnaces is mildly to moderately acidic, condensate from high-efficiency furnaces is a strong acid, containing large quantities of corrosive nitric acid. It goes without saying that you don't want this highly acidic liquid leaking all over your property.

If your furnace's condensate line runs outside your property to an outdoor drain, damage to the exposed, outdoor section of the line can allow condensate to spill down your exterior walls, ruining your siding and dissolving concrete and brick mortar. Indoor leaks can ruin drywall, badly damage many types of flooring, and can even damage structural timbers and floorboards if the leak goes unrepaired for a long time.

Condensate line blockages can be even more damaging. Sometimes, a clogged line will burst and start to leak, but if it doesn't, condensate that cannot drain away may start backing up into the furnace itself.

Condensate backups can cause severe corrosion within the furnace and may cause irreparable damage to expensive components. If condensate floods into the combustion chamber, your furnace may stop working entirely. Backed-up condensate can also spill out of the furnace housing and onto your floor, causing even more problems.

What Should You Do If Your High-Efficiency Gas Furnace Has Condensate Line Problems?

If you spot liquid leaking out of your furnace, any part of its condensate line, or any exterior traps and/or neutralizers attached to the line, you should shut the furnace off as quickly as possible. Do not attempt to repair the leak yourself, and take great care when cleaning up any spilled condensate (goggles and gloves are essential).

You should then call in a heating system repair service as soon as possible. These services will find the source of the leak, and repair or replace the damaged section of the line. They will also remove any solid debris causing blockages within the line.

You should also have your service perform a full inspection of the furnace's internal components, to look for any hidden damage caused by corrosive condensate.