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New high efficiency gas furnaces are amazing pieces of home technology. They are saving the environment and, for those of us more monetarily motivated, reducing our energy bills. With these upgraded furnaces a new problem has developed. They produce a lot of condensate water that has to be removed and drained appropriately. It's not as simple as running it down the drain.
See what’s wrong in this picture of the crawlspace I was in?
Yes, there is a dirt floor and no vapor barrier. Look again, there is another problem more specific to high efficiency furnaces. The furnace condensate line, which drains all the water produced by the furnace, empties straight onto the ground.
New high efficiency furnaces put out a lot of water (actually acidic water, but I will get to that in a minute). There used to be a puddle under this condensate drain line but I placed a 5 gallon bucket under it the night before. In 24 hours this furnace produced around 1.5 gallons of condensate water when the outside air temperature averaged 30 degrees. This furnace came on in November and continued to dump around 1.5 gallons of water on the ground every day. We can estimate that 140 days later around 210 gallons of water was added to the crawlspace! And that’s on top of the normal ground moisture!!
One of the by-products of burning gas, be it propane or natural gas, is water. In less efficient furnaces this water goes up your chimney as water vapor (unless it cools and recondenses on its way up, but that’s another post) along with the other by-products of burning gas. In high efficiency furnaces a second heat exchanger actually takes heat out of the water vapor causing the water vapor to condense into liquid water.
If only that liquid water coming out of your condensate line was clean water there would be no problems. However, during the furnace combustion process water vapor is mixed with nitrogen, which accounts for around 78% of atmospheric air. H2O plus nitrogen creates nitric acid with a pH of 4, plus or minus 1 point. To put that into perspective, acid rain is around 5, orange juice is 3, and pop and beer are 4. While you can drink pop and beer furnace condensate is still not safe to drink.
Anyway, back to why the HVAC installer (who is licensed in Ohio) dumped the condensate on the ground in the crawl space (other than perhaps being lazy). You shouldn’t run the condensation simply down the drain because it can corrode metal (it’s also illegal in some localities). It can harm septic tanks. Run it outside with the A/C condensate line? Not a good idea because the line can freeze over in winter and cause your furnace to stop working.
So, dump it on the ground in the crawlspace is the easy answer. Dumping the condensate on the ground (along with other issues) helped lead to a crawlspace nightmare. Adding all the extra water drove up the humidity level and moisture content of the wood framing. High humidity in crawlspaces can lead to mold and bugs. I’m not going to delve into the other problems encountered in this post but you can read about them in my other posts about crawlspaces. Needless to say, adding moisture to crawlspaces is bad.
The ideal way to deal with high efficiency furnace condensate is to first neutralize it. Various manufacturers make inline condensate neutralizers that bring the pH level close to neutral by simply running the nitric acid over a neutralizing agent. You can see in the diagram below from InterNACHI that the neutralizer treats the water on its way out of the furnace and into the drain.
Neutralizers bring the pH level close enough to neutral to safely run the condensate down the drain. All drains should have an air gap and be trapped. Neutralizers are simple and relatively inexpensive for your HVAC serviceman or other qualified individual to install.
I recently visited a crawlspace and found a host of problems that, individually, most likely would not have created a big problem. But, as the handful of different issues came together they added up to a real problem for the homeowner. Air leakage from furnace ductwork plays a critical role in determining crawlspace environments.
Furnaces can be located in attics, in the living area of the house, or in basements. For homes with crawlspaces, the warm supply or cold return line will often run below the floor. If your heat comes from registers that are on the floor, then the heat supply lines run under the floor through the crawlspace. You have what’s called a downdraft furnace.
While this is generally fine, the installers failed to do one significant thing when they installed the ductwork in my problem crawlspace. They never sealed the joints in the ductwork.
Obviously, the ducting leaked. It leaked so bad that whenever the furnace turned on you could feel the air blowing out of the crawlspace hatch. Warm air filled the insulated crawlspace all winter long keeping it around 55+ I would guess. I didn’t have a thermometer so I’m guessing based on the amount of sweating I did while crawling around.
It used to be that foil tape was used to seal the joints, but this has fallen out of favor for many installers. Today, HVAC installers primarily use a type of mastic sealant that is brushed on (I have also seen similar products sprayed on).
Before this ductwork was sealed, whenever the furnace came on the spider webs hanging on the floor joists would start blowing all over. After it was sealed the air in the crawlspace remained still. And, no more air came pouring out of the crawlspace hatch.
This is a photo of the same area that was not sealed in the previous picture.
If you look closely, in the first picture the ground is bare dirt. In the second picture you can see that a vapor barrier was added. The moisture coming from the bare dirt was being heated by the warm air coming from the ductwork. The warmer the air, the more moisture it can hold.
Continuous warm moist air all year long is a great breeding ground for mold and wood destroying insects. Not to mention the spiders higher up the food chain!
Here in Ohio the winters are pretty cold and insects and mold should not be active. Winter is a time for drying, but the joists in this crawlspace were maintaining over 15% moisture content. I really wonder what it would be during the humid summer months? So, make sure any ducting in a crawlspace is sealed. And while you’re at it put a vapor barrier down as well or you can end up with unwanted house guests.
Dryer vent maintenance is one of the last things on my very long list of to do’s. While doing laundry this weekend I noticed my dryer vent was not heating up very fast so I went outside to check the vent.
According to the U.S. Fire Administration’s Clothes dryer fire safety outreach materials, 34 percent of the 2900 fires and 5 deaths were caused by lint buildup from not cleaning. One sign of lint buildup is a dryer that takes a long time to dry. I guess it's time to get out some tools and check my vent.
Thankfully my dryer vent is relatively short so it probably won’t require any specialized tools. A long handled brush will do. If you have a longer duct system or long sections of duct that need cleaning you should invest in a duct cleaning brush. Brushes are fairly simple like the Deflecto Dryer Brush. There are a variety of brushes that you can get through your local big box store.
If you’re buying a brush to clean out a flexible duct that has ribs on the inside instead of being smooth, don’t. Throw your duct in the trash and buy new smooth ducting. The ribbed interior catches more lint and thus clogs quicker. Plus, it’s more likely to get kinked when slid back into place.
Use rigid metal instead. Also, forget the screws. They are great at catching lint inside the ducting. After sliding my dryer out and dismantling my duct, here’s what I found.
I used my long handled nylon brush to scrape the lint off the inside of the duct work. You have to scrape the lint with a brush because it is sticks to the inside of the pipe. It won’t fall off. It can’t be vacuumed out. After cleaning my duct I have one more step before putting everything back together.
While the dryer is out and the vent is off I need to use this opportunity to vacuum out the back of my dryer. Get as much lint as you can see.
The last thing to do is cleaning out the dryer vent cover shown in the first picture.
It’s time to put everything back together. Be sure to connect your ducting in the right direction. The first section from your dryer slides into the second. The second section slides into the third, and so forth until you're connected to the dryer vent cover. When sliding your dryer back in place be careful not to damage any duct. When my dryer was originally slid back in place the metal duct was dented. These dents caused severe buildup of lint inside the duct.
After I was all done I turned on my dryer and went outside to check the vent. I could tell immediately that my dryer was pumping out a lot more air.
The U.S. Fire Administration advises cleaning your ducting every three months. When ducting has lint built up inside, your dryer will start to seem like its taking longer to dry your clothes. So, if you notice your dryer is not working well, check for lint. Finally, be sure to clean the lint filter after every load. Cleaning your lint filter is the number one way to keep lint out of your dryer and duct work. A little maintenance can go a long way to prevent common problems.