Where did you find the .03 value for supply outlet and for the return grille? Is this the sum of the grilles in the total system or the sum of the grilles along the total effective length or some type of standard value, as I see it everywhere in pressure loss discussions???
You obtain that information from the grille and register manufacturer, you’ll find it in their performance data or engineering data for the specific grille or register that you’re going to use. That pressure drop that is included is the one grille that is in the critical path or the longest circulation path. You can have multiple grilles if you’re doing a central return and you’re using transfer grilles.
Hi Ed just makin sure now, the friction rate is on each manual of the air handler depending on the speed of the blower? And we have to match that friction rate based on how we calculate sp, pressure drop, equivalent length, etc after the design is complete correct?
No, we use The blower performance chart that’s included in the air handler as part of the process to calculate our friction rate using the guidance of Manual D
Im so confused. WHAT IS FRICTION RATE? I've been researching for hours, and I don't understand this term. You also brought up a good point, how can we determine what filter the system can afford??
I do teach. I just started with ACCA so watch their offerings for classes in the fall. I am doing a psychrometric class (virtually in a few weeks). There is more of my content (RU-vid) on hvacairflow.com
Ed, were you previously with Eastern Cooling council and teaching the continuing education courses for the required hours to maintain hvac master contractor license?? If you’re no longer doing that is there anyone you recommend??
3m/Filterate definitely do not publish accurate 'initial resistance value (WC)' that they print on their products. If a real consumer advocate group tested their products, they would be forced to change the printed information to double or triple those figures at those CFM ratings. I am an HVAC business owner and have tested these filters in numerous MPR/Merv ratings, plus different system designs and they are not even close to those numbers. I easily saw double the values printed in every system tested. Unsuspecting people put those in their furnaces or air handlers thinking they struck gold, but they got fooled by fancy wording. They are junk and it is best to still with a better filtration system instead of wasting money on that garbage. But all brands should be forced to print some accurate data just as the EPA makes companies put out accurate information for items they regulate. False advertising at best, but really it is fraud. Love you videos, btw!!
Thanks Kevin. If you want to go down a fun rabbit hole find ASHRAE 52.2. That is the standard that filter manufacturers are required to test PD and MERV ratings. This might explain the discrepancy that you’re seeing. Many filter manufacturers publish. Their pressure drops at velocities that are two or three times less than what we measure in the field. I have another video that says something about filters, if you haven’t watched that one I explain some or maybe even all of what I just wrote. And I’m not going back to proofread this this is voice to text figure it out lol.
@@edwardjanowiak Thank you for responding. I am a huge fan of our teachings online on the taped videos and your persona channel. You have really changed the way I view heating and cooling. And your humor makes it great to learn. I will definitely look into that ASHRAE 52.2 and read up. I look forward to it. And I think I only have a couple videos left of yours to watch but might go back over the big conference videos that were like 2 hours each. 20 years in the field and I always still try to learn more each day. You have given me some valuable information and I thank you.
