I would love to know more! I did very light commercial service (RTU < 10T) in the past, almost my entire 25+ years was residential focused. What is one or two key differences?
@@HVACProBlog there's a lot different. Not sure I can cover in a comment. For example, external static is measured after the cooling coil. And it's different from total static. We don't have anything called Total external, it's either total or external. And we measure cfm via a duct traverse measuring velocity. Total static is also before any fillers. Because our equipment includes everything from the factory inside the unit.
Ah yes, I see - since there are a lot of packaged systems. When changing the filter types, replacing a MERV 8 withe MERV 11 for example, I can see this also wreaking havoc on where/how to measure too...
"by verifying static is close to design"....most houses don't even have an hvac design....so now what? all you can tell without a design is if you are within manufacturer's specs for TESP which is printed on the furnace sticker info sheet. Is there anything else you can tell with TESP, speed tap setting, and air flow? Thanks Chris.
Great question! Rather than try to explain everything in a comment on Fan Law #2 and what you are looking for, please checkout this content? Why You Must Verify Duct Size When Replacing Your Furnace: Fan Law #2 Demystified ruclips.net/video/mbZKfPDA8X4/видео.html
It's interesting how this residential approach is so different than how it's done with commercial systems.
I would love to know more! I did very light commercial service (RTU < 10T) in the past, almost my entire 25+ years was residential focused. What is one or two key differences?
@@HVACProBlog there's a lot different. Not sure I can cover in a comment. For example, external static is measured after the cooling coil. And it's different from total static. We don't have anything called Total external, it's either total or external. And we measure cfm via a duct traverse measuring velocity. Total static is also before any fillers. Because our equipment includes everything from the factory inside the unit.
Ah yes, I see - since there are a lot of packaged systems. When changing the filter types, replacing a MERV 8 withe MERV 11 for example, I can see this also wreaking havoc on where/how to measure too...
"by verifying static is close to design"....most houses don't even have an hvac design....so now what? all you can tell without a design is if you are within manufacturer's specs for TESP which is printed on the furnace sticker info sheet. Is there anything else you can tell with TESP, speed tap setting, and air flow? Thanks Chris.
Great question! Rather than try to explain everything in a comment on Fan Law #2 and what you are looking for, please checkout this content?
Why You Must Verify Duct Size When Replacing Your Furnace: Fan Law #2 Demystified
ruclips.net/video/mbZKfPDA8X4/видео.html