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Furnace Duct Cleaning Questions

As a homeowner, you have a lot to maintain and it can be a bit overwhelming at times. It is easier to address the issues that you can clearly see, like peeling exterior paint, or that immediately affect you, like a heater or an air conditioner that is not working when you need it. But a lot of important components that maintain the quality and comfort of a home are more behind the scenes and, therefore, easier to overlook, such as your ductwork. While it is good to remember and maintain the more hidden workings of your house, how do you know if you actually need to actively care for things like your ductwork?

Furnace duct cleaning basics

Generally, furnace duct cleaning refers to the cleaning of the various cooling and heating system components of forced air systems. This includes the supply and return air ducts and registers, heat exchanger(s), heating and cooling coils, condensate drain pans, fan housing and motor, air handler, etc. If the entire system is properly installed and maintained (airtight ductwork), the ducts should only accumulate light dust, which the system air filters can handle. Even so, over time gaps may still occur in the ductwork that can let in moisture or more harmful particles, which will need to be dealt with.

Is furnace ductwork cleaning worthwhile?

Consider the following reasons to determine whether cleaning your ductwork is advisable.

Reasons to clean

  • If anyone in your household (or even a regular houseguest) has a compromised immune system or bad allergies, clean ductwork can improve the quality of air in your home.
  • If you recently completed major construction or lead paint remediation, it is important to ensure that none of the leftover debris is being dispersed through the ducts.
  • If any of your ducts are leaky, mold may have grown in the ductwork and will need to be cleared from the system as soon as possible.
  • If you think there is an infestation of insects or vermin in the ductwork, you will need to have them removed.
  • If there are lingering odors, such as cigarette smoke or skunk spray, air duct cleaning may help alleviate the smell.

Reasons not to clean

  • If your ductwork is not leaky and you have no other reason to think it is particularly dirty, cleaning your ducts may be a waste of your time or money. According to the Environmental Protection Agency, no evidence points to any health hazards stemming from regular light dust accumulation in ducts. Just remember to frequently replace your air filters (at least bi-monthly, if not monthly), which can be a cheaper and easier way to maintain the air quality of your home.

How do you prevent dirty and/or wet ductwork?

The short answer is to ensure your ducts are airtight. Leaky ductwork leaves room for dirty air particles and allergens to enter the ducts from your basement, crawlspace, attic, and other spaces you tend to leave as is (in other words, all the areas of the house you never, or rarely, clean). Bigger gaps in ductwork can even leave room for small critters like mice to enter.

The easy fix is to fill any gaps with insulation and then use foil-backed duct tape to cover the gaps and any cracks in the ductwork. For gaps between the duct and the wall, it might be better to use caulk to seal any openings you find.

It is also important to keep an eye on your air conditioner’s condensate pan to ensure it is draining properly. Standing water may signify that the cooling coils are not removing water from the air as they should, which could result in damp insulation and, eventually, mold issues.

What are the costs of hiring ductwork cleaners vs. doing it yourself

Hiring costs

Depending on the size of your house and where you live, you should expect duct cleaning professionals to charge anywhere from $300 to $1000 and take at least two hours up to multiple hours spread over two days.

Be on the alert for scams, though. Super cheap offers often come with hidden costs. Check with the Better Business Bureau or the National Air Duct Cleaners Association to ensure you are working with a legit business.

DIY costs

While it may be possible to clean your own ductwork, most people do not have the necessary tools (high-powered vacuum and special rotary brushes) or know-how to do it well. If you are not careful, you could unknowingly dislodge or disconnect something and cause damage to your heating or cooling system. So, if you really have an issue with mold or vermin, it is best to leave it to the professionals. However, if you simply want to do a general cleaning of your furnace ducts and cannot afford hiring a professional cleaner or any special tools, you can do a “stop gap” cleaning job with regular household tools and materials.

How do you clean ductwork?

If you do decide to clean your own ductwork, remember to never use steam cleaning or any other cleaning method involving moisture.

Tools and materials

Be sure to have the following tools and materials ready when you start cleaning:

  • Vacuum—While you can use a typical household vacuum with a good hose attachment, a heavier-duty shop vacuum is a better choice.
  • Brush—A stiff-bristle toilet brush or something similar works best.
  • Screwdriver—Check what fasteners are holding your registers in place, then grab the necessary screwdriver.
  • Paper towels—These come in handy to cover some registers while you clean others.
  • Air filter—After you are done cleaning the ducts, you will need to replace the current air filter with a new one.

General furnace duct cleaning steps

  • Cover the supply registers with paper towels. Remove the register, wrap a paper towel around it, then refit the register. This will help keep excess dust from blowing throughout the house while you are cleaning.
  • Run the forced air system fan. On your thermostat, turn off the heat/cool mode and then set the fan to on. This will move the dust along that you will be loosening.
  • Ensure your old air filter is secure. This protects the fan motor from the excess dust.
  • Loosen any dust stuck in the ducts. Use the handle of your brush to carefully tap the sides of any ductwork you can access in your basement.
  • Vacuum out the supply registers. Remove the register and use the vacuum hose to catch any dust and other particles that are being pushed out by the fan. Carefully vacuum as far into the ductwork as your hose will easily reach. If necessary, use your brush to loosen any built-up debris you see in the register. You can discard the paper towels as you clean each register.
  • Vacuum out the return registers. Remove the register (you will likely need to unscrew them), then follow the same cleaning procedure as you did for the supply registers.
  • Shut off the fan at the thermostat and power off the furnace at both the service switch and the breaker panel. This is a crucial safety precaution before you clean the furnace itself.
  • Vacuum out the furnace blower compartment and return air boot. Remove the panels on the front of the furnace so you can vacuum out the blower compartment and return air boot. This is where most of the dust will be lodged. It is also a good idea to clean the furnace fan while you have access. Be careful not to damage any components inside the furnace. Securely replace the panel when you are done cleaning.
  • Replace the air filter. Discard the old air filter and replace it with a new one. Remember that it is important to regularly change out your filters.

If you have a mold problem, it is crucial that you remove and replace any potentially affected insulation. You will also need to determine what caused the issue and fix it, otherwise the mold will simply reoccur. This will likely require the help of a professional.

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