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PVC Outgassing: What's The Fuss?

Pipes have been made of many materials over the years including copper, iron, aluminum, clay, and even wood! Plastic, in the form of polyvinyl (PVC) pipe, is a relatively new addition to the mix. PVC pipe has been approved for use in both fresh and wastewater applications, and is also used in exhaust applications for high-efficiency furnaces.

Billions of pounds of PVC are made each year and home construction, repair and remodeling materials often contain PVC. A debate has arisen over the safety of PVC in homes, and that’s causing some people to rethink their use of PVC-containing materials.

A phenomenon known as “outgassing” is at the center of the concern over the use of PVC-containing materials. Outgassing refers to the release of volatile organic compounds (VOCs) from products that contain PVC. VOCs can be released from the PVC into the air or water and have been implicated in “sick building syndrome,” and other indoor air quality issues. Further, VOCs can be found in water that’s been carried through PVC pipe.

When heating is involved, the use of PVC requires some special considerations. High efficiency furnaces are designed to vent directly to the outdoors. They also take in fresh air from outside the home, rather than recirculating semi-heated air already inside. PVC is used in heating applications mainly because it’s inexpensive. It’s also able to stand up to the stress of repeated heating-cooling cycles.

The furnace exhaust, which contains the noxious by-products of combustion, is hot. (After all, it’s just come out of the furnace, right?) Heat tends to accelerate the release of VOCs, so when PVC is used as part of the furnace exhaust system, the amount of VOCs released into the outside air (and the inside air around the exhaust pipe) tend to increase.

Some homeowners who are concerned about PVC outgassing and its long-term health effects have begun looking for alternatives to PVC for their furnace exhaust ports. When a substitute for PVC is sought, we generally recommend stainless steel. Stainless steel is certainly more expensive than PVC but it’s inert so it won’t interact with the environment around it. It also tolerates the repeated heating-cooling cycles and moisture from the outside air (and dampness in basements) very well. Since stainless steel is durable, it will also generally last the lifetime of the furnace.

If you have a high-efficiency furnace and are concerned about PVC outgassing, or would like to look at alternatives to PVC for other applications (like plumbing), please give us a call at Boston Standard Plumbing & Heating at (617) 288-2911 for a consultation. We’ll be happy to suggest alternative plumbing, heating and cooling materials.

High-Efficiency Furnace Tune Up Time

Now is a great time to get your high-efficiency furnace tuned up for winter heating. Boston Standard Plumbing & Heating offers these tips to help you get ready for the colder fall weather.

High efficiency furnaces typically take in fresh air and exhaust to the outside. High efficiency furnaces can be vented through pipes at or near the foundation level of your home. If your furnace vents horizontally through the foundation wall of your home, it’s very important to keep these pipes clear of any debris that may have accumulated during the summer or early fall. This can include spider webs or other small nests, leaves and other organic matter.

When you attempt to remove debris, be sure you don’t accidentally push the material further into the pipe! Most organic materials can be removed manually. Dry organics like leaves and webs can also be removed with a shop vacuum. Remove any weeds, branches or overgrowth within several feet of either port to ensure proper airflow to and from the furnace. Don’t cover the ports or store any materials around them, either. Stored materials can trap leaves and promote the collection of snow and ice around the intake and exhaust ports.

Furnace exhaust gases can be corrosive. Examine the wall space around a horizontal exhaust pipe for signs of damage, which might include discoloration or surface pitting. This kind of damage may indicate that your furnace isn’t venting properly, and it is important to remedy this immediately. Consult with Boston Standard Plumbing & Heating , and we can replace your existing vent or revent your furnace if necessary.

During the heating cycle, some moisture will condense inside the pipes and on the heat exchanger. The intake and exhaust ports are constructed to allow this water to run back to the furnace to drain. It’s possible for condensate to freeze in long pipe runs, potentially damaging the exhaust port pipe and enabling carbon monoxide and other harmful gases to enter the home. Insulating the pipes can provide some additional thermal protection, but even pipes that have been insulated should be inspected for cracks or other signs of damage.

The condensate runs to a household drain through a special drainpipe, which can also freeze. If the condensate drainpipe freezes, your furnace will shut down. Check your condensate drain to ensure that it is free flowing. If the drain appears to be clogged, contact Boston Standard Plumbing & Heating and we’ll clear the condensate drain. If your furnace operates in an unheated space, you may want to insulate the condensate drainpipe to ensure uninterrupted operation.

Boston Standard Plumbing & Heating offers heating inspections and tune-ups. Contact us at (617) 288-2911 to schedule your appointment.