What's Your Opinion on Duct Cleaning?

[2manyrocks]

I am not the only one skeptical about whether there are any real benefits to duct cleaning. Should You Have the Air Ducts in Your Home Cleaned? | US EPA

Would also say that a magnified view of dust particles from a bore scope might tend to blow them out of proportion, too.

 

[jaxs]

There's no shortage of opinions so I'll reserve mine and state a few facts instead.
#1 If supply ducts are dirty your filters aren't working.
#2 If supply ducts are dirty the evaporator coil is caked,100% guaranteed.
#3 They can spit shine ducts but if coil isn't cleaned you were scammed.
#4 You can retrofit a first class filter rack much cheaper than cleaning ducts and good filtration pays for itself several times over in efficiency and extended equipment life. Not to mention there will be no need to clean ducts nor coils going forward.
#5 I wouldn't allow metal duct to be coated inside if it were free.
#6 Whoever has 2 labs in house and can see through filter when changed once per year. One of two things is wrong,intake duct has leaks or air is finding a way to detour around filter. Hair is only half the equation , constant movement keeps far more dust airborne than would be the case for two human occupants( ditto for 5 to 14 year-old kids)

 

[MossRoad]

A lot of times you'll know how bad your duct work is just by looking at the squirrel cage on the on the blower motor. If Those fins are caked with dust / dirt, your duct work is most likely caked with dust /dirt as well.. It's best to have all the cracks and seams sealed up on the return side before the furnace / AH.
The best thing you can have done to the supply side is to have new duct work installed and have the insulation on the outside of the supply duct.
Dust particles in the home is possibly coming from the insulation fibers braking down inside your supply duct, and being blown inside the home.

I used round duct here and it's insulated on the outside with metal supply duct also insulated on the outside. and of course, all seams are sealed with mastic, and or tape .

What are these insulation fibers you speak of?

All we have is 6" round metal ducts going to each floor register in the house. 9 of them.

In several places around the house there are floor mounted air returns. 3 of them. Those are just space between floor joists with a metal sheet nailed up to the bottoms of the joist. So 3 sides wood, 1 side metal. Anywhere they have to go across the joists, there's rectangular metal ductwork hanging below the joists.

No insulation on anything or in anything.

 

[MossRoad]

A lot of times you'll know how bad your duct work is just by looking at the squirrel cage on the on the blower motor. If Those fins are caked with dust / dirt, your duct work is most likely caked with dust /dirt as well.. It's best to have all the cracks and seams sealed up on the return side before the furnace / AH.
The best thing you can have done to the supply side is to have new duct work installed and have the insulation on the outside of the supply duct.
Dust particles in the home is possibly coming from the insulation fibers braking down inside your supply duct, and being blown inside the home.

I used round duct here and it's insulated on the outside with metal supply duct also insulated on the outside. and of course, all seams are sealed with mastic, and or tape .

Oh, and yes, several years ago the fan went out, I pulled it and found it filthy. I cleaned it and replaced the motor. That's around the same time I ditched the electrostatic air cleaner. It's been pretty clean ever since.

 

[kenmac]

What are these insulation fibers you speak of?

All we have is 6" round metal ducts going to each floor register in the house. 9 of them.

In several places around the house there are floor mounted air returns. 3 of them. Those are just space between floor joists with a metal sheet nailed up to the bottoms of the joist. So 3 sides wood, 1 side metal. Anywhere they have to go across the joists, there's rectangular metal ductwork hanging below the joists.

No insulation on anything or in anything.

Main duct work is usually insulated on the inside. your run supply to each room is either flex, or metal insulated on the outside. I have never known of round metal supply run outs to each room insulated on the inside.
Some older homes had square metal supply ducts to supply each room, and I've seen some insulated on the inside, and some not.
It doesn't sound like your return is insulated on the inside like they have been for the last 50 yrs ?.

If you have square main supply duct, and if it's insulated on the inside, When your blower motor comes on, you're most likely getting those insulation fibers blown into your home. That insulation will begin to come apart over the years and ends up in your home where you're breathing those fine fiberglass fibers.

If you have your main duct worked cleaned, all your doing is stirring up those insulation fibers more, and possibly causing more of the insulation to come apart inside your duct work

 

[kenmac]

Oh, and yes, several years ago the fan went out, I pulled it and found it filthy. I cleaned it and replaced the motor. That's around the same time I ditched the electrostatic air cleaner. It's been pretty clean ever since.

if your squirrel cage is clean. your filter is doing it's job of containing most of the dust and dirt being sucked back through the return and re distributed in your home. Of course your A/C will catch some of it, but after the A/C coil there's nothing but duct work and insulation and nothing to prevent those insulation fibers from being blown into your home. Unless you have a filter in each register, which you can purchase for each room

 

[MossRoad]

Main duct work is usually insulated on the inside. your run supply to each room is either flex, or metal insulated on the outside. I have never known of round metal supply run outs to each room insulated on the inside.
Some older homes had square metal supply ducts to supply each room, and I've seen some insulated on the inside, and some not.
It doesn't sound like your return is insulated on the inside like they have been for the last 50 yrs ?.

If you have square main supply duct, and if it's insulated on the inside, When your blower motor comes on, you're most likely getting those insulation fibers blown into your home. That insulation will begin to come apart over the years and ends up in your home where you're breathing those fine fiberglass fibers.

If you have your main duct worked cleaned, all your doing is stirring up those insulation fibers more, and possibly causing more of the insulation to come apart inside your duct work

Ahh. Thanks.

No. We don't have any insulation on or in the 6" round ducts to the room floor registers, or any insulation inside or outside of the returns in the joist spaces or rectangular ducts.

No flex pipe anywhere.

House is 100 years old. Furnace is at least 35 years old.

 

[MossRoad]

Ahh. Thanks.

No. We don't have any insulation on or in the 6" round ducts to the room floor registers, or any insulation inside or outside of the returns in the joist spaces or rectangular ducts.

No flex pipe anywhere.

House is 100 years old. Furnace is at least 35 years old.

Just searched an old thread and found our furnace was installed in 1984. Armstrong. So 40 this year.

 

[Topzide]

I have a filter in the return grate and another at the HVAC unit. The grate filter tends to catch most of the "crap" before getting to the unit, where the other filter lasts 2 - 3 times longer. The ductwork has stayed clean. Have access hatch to keep an eye on it.

 

[ponytug]

FWIW: Putting filters on the distribution registers or grilles does add significantly to the fan back pressure, and that degrades the heating and cooling performance. Back pressure also increases losses from any cracks, or poorly sealed joints in the ductwork, further degrading performance.

I think of register filters as a temporary solution, e.g. while ducts are being cleaned, rather than something that is desirable longer term.

Intake/return filters are a different story in my mind. I have noticed that over the years the filter quality (e.g. MERV) keeps improving (creeping up), but dropping in a higher performance filter in an older system may mean the fan speed needs to be adjusted to maintain the heating/cooling system effectiveness. I'm all for better filtration in the interest of health, but sometimes, it is not simple.

We have an indoor air quality (particle) monitor that has helped me tracked down leaks, and when to turn on portable air filters.

All the best,

Peter