Q: d-i-y duct cleaning: shop vac recommendation?


I would like to clean the ducts in my house (1966 ranch; 1400 sq ft main level - floor registers, 1200 sq ft basement - ceiling registers; Denver metro.) Nothing _terribly_ wrong with the air flow, but a couple of the registers are producing mediocre air flow, so I just want to make sure and do some duct cleaning. I should add that this is not an issue of anyone in the house suffering from allergies or anything like that. Just trying to improve the air flow to make the whole heating/cooling system more efficient.
I've read several threads on this discussion group, and it sound like I should avoid duct cleaning services, which usually are not worth the price they are charging. So I'm thinking of getting a shop vac and cleaning the ducts myself - just push in the shop vac hose as deep as I can and try to vacuum all the junk.
I'm pretty new to this, so is there a specific shop-vas type/model/brand that you would recommend for this type of job? Note: the narrowest vent openings are 1 3/8 - 1.5 in.
I'll appreciate any helpful pointers. No flames/sarcasm, please :)
Cheers, Bubba
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snipped-for-privacy@yahoo.com wrote:

so that's probably NOT what's going on. If you really have sub-standard airflow, it's more likely that a duct has collapsed as a result of something falling on it in the attic (e.g.). Or perhaps your furnace fan is now only operating on low speed or is binding.
If you want to clean the ducts on general principles your best bet is probably to forget about the shop vac and instead go to Harbor Freight and get one of their $3 +/- dryer vent brushes and swish it around in the ducts while the furnace fan is running.
Everything I've read indicates the commercial duct cleaners are mostly purveyors of snake oil.
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CJT wrote:

Those are possibilities, but more likely it's just a function of system balance. At full damper opening, all the various outlets likely vastly exceed the CFM rating of the furnace blower. With the registers all open the airflow is going to vary at each register based on the restrictions on it's particular run, i.e. twists and turns. By reducing the damper setting on registers close to the furnace you provide more air to the further out registers.
An HVAC tech would balance the system by checking the CFM spec on the furnace, dividing that by the number of registers and then using a CFM bal-o-meter to measure the output at each register adjusting each several times until they are all flowing correctly.
Of course when you close off heat to a room you don't use in the winter or A/C to a room you don't use in the summer it throws things out of balance and since nobody thinks to mark the original damper position, in a year or two the system is hopelessly out of balance.

Bad idea since that will blow everything you knock loose out into the room.

I wouldn't go that far. Duct cleaning is certainly something that should be done as no furnace filter will trap everything and there will be crud buildup. I think the issue is that some duct cleaning services for the residential market don't do a very good job and sometimes have marketing that exaggerates a bit.
Pete C.
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Pete C. wrote:

... where you easily clean it up.

I would.
http://www.epa.gov/iaq/pubs/airduct.html
Duct cleaning is certainly something that should

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Not the guys I had do my last house. They stuck a pneumatic air hose in the vents with some kind of rotating head on it with some spaghetti-like rubber bristles about 6-8" long, and put a vacuum thing on the furnace-end of the system. The air hose thing beat the dust loose and the vacuum pulled it out.
I had it done only because the hardwood floors had recently been refinished, incl. sanding to bare wood. It had probably never been done before either, 40 year old house.
As another poster said though, your problem probably isn't the dust. It's either a physical obstruction in a branch supply (or return), or the furnace's blower is going bad, or some other issue.
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If previous owners had animals etc, the return ducks are the problem.
The house I purchased NEVER had the ducts cleaned before. (50 years) When I swtiched from oil to gas heating replacing the original furnace I had the duct profesionally cleaned.
WOW, there was LOTS of crud on the return ducts. (each room in my house has a return duct and a heating duct) The heating registers werent too bad, mainly because the crappy old filtering systems did do somewhat of a good job in its years of use. The intakes though had dog hair, baseball cards, monopoly money... All fun things in them.
For the 250.00 I spent I feel I got my moneys worth out of them. They were there for 4 hours cleaning out the system. Now that they systems been cleaned, I would LOVE to get some sort of filters to trap crap from getting into the intake registers...
Can this be a DIY job???? Humm maybe. Thats if you can get into the ductwork easily with a decent brush or something. To get the stuff sucked out of the system they cut a hole by the furnace ducts and attached a bigass hose from a truck to my furnace. Can you create that kind of suction needed??? Maybe but not with a standard shopvac.
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