low flow at registers

Do you test for low air flow at registers? How do you test it?

If you believe it is “lower than typical” do you quantify it? If so, how do you quantify it?

I don’t measure CFM, but I do use an anemometer if it is a lot lower than the rest I sate it.

look for 400 to 600 fpm or 2 to 3 meters per second

Bathrooms and very small rooms at the low end, higher by large picture windows or patio doors. pull the register, 6" pipe may have higher 4" round lower velocity, most will be 5" round. They don’t have to be the same velocity, different pipe diameters will have different velocity if registers are the same size.

If I was going to meassure airflow I would use a flow hood. I would want to compare the actual flow with the computed load calculation desired flow.

Not airflow but just basic “when does it heat up in here” after having the furnace on for about 30 minutes on a cold day, I was somewhat dumbfounded that the temp didnt rise in the home. Found the crawlspace access and went in…This is what I found and it was nice and toasty in the crawlspace.

Yep someone forgot to put in the damper. I wonder what the air flow is.

I asked this because an agent chewed me out because I did not “quantify” the little to no air “flow” at several registers. He feels I should have measured the “flow” and offered solutions. I was hoping to learn what the duty of care would be from your opinions.
From my immediate circle of colleagues we all agreed the “hand” test while the furnace fan is set to ON, comparing register to register and compared relative to our overall experience is the standard test method for “flow”.
How do you do it?

Sign up here Mark http://www.achrnews.com/articles/measuring-duct-system-performance and you will get all the info you need. You would be correct to inform the agent that over and above balancing is the only way to make sure everything was done correctly. Way above what a standard inspection gives you time for.

Good article Kevin, but tell me, as part of your process… what do you do in your routine to assess airflow? And if you found little to none how would you proceed and report? What I’m looking for is a home inspector’s test method, not a specialist’s.

You need more than an anemometer.

You need more than a flow hood.

You need more than a manometer.

You need more than a Ductulator.

You need more than the information of the J letter.

You need more than manufacturers equipment specifications.

You need more than a hygrometer.

You need more than a psychrometric chart.

You need more than a Realtor that knows the scope of a home inspection…

Oh, did I mention this is not your responsibility?

But if you’re going to talk about it in your inspection report you better have something to back up your observation.

do You have a picture of that ductulator thing?

Verification with a air velocity meter but only for a quick visual for the Client.

Kinda of the opposite of what I was asking. … but yes! Thanks David. My point exactly. I was just hoping to complie a consensus to find a duty/satandard of care

James it is not a picture but a program for calculations.
You might be thinking of this but I am not sure.

Sorry Mark, was addressing the flow of this thread and towards your realtor, more than you.

As for airflow as a home inspector, the back of my hand is sufficient calculation. We’re not trying to calculate or measure CFM we are trying to measure flow ( FPM).

The distance of air “throw” is relative to its flow.

Temperature rise is related to flow.

Air stratification is relative to flow.

With a little practice, the back of your hand (which is actually more sensitive than an infrared thermography camera) works just fine when I’m talking to a Realtor.

Do you remember the days of using a coat hanger and a bag David?

Thanks David…BTW love the “Get-IR-Done”. That’s bloody good!!