So over the past 2 days I tested the 416 against a couple of Infinity controls. The results improved within the 75 CFM range of one another. With the formula provided by Jim, CFM was even closer. I guess I must have done something wrong to be off like I was before.
Jim, should I be using the traverse chart on your site for the 416 or split the return duct 3 ways as even as possible? I've been splitting it as even as possible.
Thanks for all the responses!
I have had the best luck with the chart (log method) versus the equal squares method. There have been several articles written about both methods. The sides are split on which is the most accurate. When it comes to turbulent airflow and duct profiles that are not optimized I have found the log method the best. Glad you are getting better results. I best if you measure again following the chart you will be closer.
I have had good luck with just 3 traverses across a 10 inch return duct.
I have a chart in my truck, that lays it all in the log-linear method, that I like better than the TruTechTools chart (sorry Jim:() for the reason that it is simpler to read. I can't find it in pdf right now, but if you remind me in the morning I will scan it and attach it here.
I agree on the accuracy of the log linear vs. the equal area method. I believe the log linear argument holds more water. :cheers:
Originally Posted by jim bergmann
No harm no foul for me, I would be interested to see it. I made that one and broke it up into millimeters to make it easier to make the measurements as in the log methods you end up working in 10ths of an inch.
By the way Jim, if you have time I would appreciate your in depth explanation of the two methods. Here is a thread I started a while back that didn't get much response on the subject. http://hvac-talk.com/vbb/showthread....ht=tchebycheff