So I had a furnace guy out today to replace the blower motor on my furnace, and he said a couple things about my ducts. First, he said I didn’t have enough return capacity- I have two returns, both 8" round ducts in a 2000 square foot, two story house. Second, he said I needed to get the ducts cleaned, as they have maybe a quarter inch of dust all around the part you can see.
First, is that really too little return capacity? It seems like that would be covered by code, the house is 14 years old and I’m sure it was built to code. If it is too little capacity, what could I do about it now?
Second, do I really need to get the ducts cleaned? I always assumed that was a total scam, but this guy’s company does not clean ducts so he wasn’t trying to sell me something.
Also, he said I should change filters once a month. That seems excessive to me. I change them about every 500 hours of the furnace running or so (my thermostat keeps track of how many hours it has been running) and when I change them they are never really dirty. I have one cat that does not shed very much, and I don’t live in a particularly dusty area.
I don’t know anything about the capacity issue, but I’ve read a bit about duct cleaning.
According to the Washington Post, “In most cases, it’s unnecessary.” See http://www.washingtonpost.com/wp-dyn/content/article/2005/11/02/AR2005110200676.html#
The U.S. Environmental Protection Agency says “Duct cleaning has never been shown to actually prevent health problems”. The EPA says that cleaning your ducts is not necessary unless you have “substantial visible mold growth inside hard surface (e.g., sheet metal) ducts or on other components of your heating and cooling system”; your ducts are “infested with vermin” (eww); or clogged with excessive dust that “debris or particles are actually released into the home”. See Indoor Air Quality (IAQ) | US EPA
The Canadian Mortgage and Housing Corporation says that “although there is little research data to support this”, it may make sense to have your ducts cleaned if you have water in your ducts; if you’ve moved into a newly constructed house, and “have doubts about the diligence of the construction crew”; and “if you are having trouble with furnace airflow, a duct cleaning could reveal significant blockages.”
The CMHC site says that if you see debris in your return air register, “you may want to have it removed.” (I assume they mean have the debris removed, not the air duct). The website says that you can do it yourself with a vacuum cleaner. See Canada Mortgage and Housing Corporation | CMHC
Since your furnace guy recommended it, I don’t know whether this is helpful, but in general, it looks like it may not be worth it.
First of all, this guy is obviously trying to sell you something. I don’t know how to determine the proper return capacity, and I don’t even know if duct size is covered by code. I doubt the statement about dust in your ducts, did he show you?
Changing filters once a month is pretty much the standard recommendation. But if yours aren’t very dirty when you change them then you’re doing fine. I use micro-fine filters and they get very dirty, so I change them every 1-2 months.
I just checked my unit. My return air downstairs is 12x24 or 288 sq inches. An 8 inch duct is Approx 50 sq inches two will be 100 sq inches. So you may be a litltle short.
If you have dust 1/4 inch thick on your supply ducts it might be a good idea to have them cleaned. Did he show you the dust or just tell you about it? That seams like a lot of dust! I would only expect that much dust in a dirty enviorment and no filter or the filter being by passed. Also it would be hard to get that dirty in only 14 years.
Also a lot of filters out on the market only stop a little of the dirt. We use to call them dust stops, the only stoped about 5% of the dust. Get the pleated ones.
If your furnace has AC also then the filters really matter to keep the evaaporator coil clean. If it is only heat the filter keeps from spreading the dust around the house.
I can never keep up. Cleaning your ducts? Is that what the kids are calling it these days?