Filter Face Velocity and Why it really Matters

[@NatetheHouseWhisperer]

Fantastic video Jim! Love the visual demonstration of how the filter in your Big Air Drop loads evenly vs the filter where the air has to turn a corner.

[@michaelmaclachlan2152]

Great stuff Jim, You are leading our industry out of the dark ages

[@CHOMAHOMA]

Big fan of hvac studies, experiments and science applied to comfort systems. Thank you.

[@hozerhvac4406]

Great video!!! I’ve been tracking it in measurequick! One thing some of my guys get confused about believe it or not is what type of filter to select in measurequick. A video on different types of filters would help guys select the correct input into MQ ( 40% pleated,90 media ect.)

[@measureQuick]

I have the guys updating that section to add some MERV rating so it is more clear. Thanks for the feedback.

[@Holler_Rat]

Gonna take a look at GeneralAire. Thanks Jim!

[@NorCal-refrigeration]

Good info. It’s all merv 13 now for public applications.

[@scottallen5182]

Great job Jim!

[@greengo7656]

Really appreciate this content! I’ve got a similar study going on a Colorado home with a GSHP and a HRV. I’ve got a 4” electric media filter and Havens on Return, Supply, AND exhaust and intake for HRV. I’m adding a humidifier and looking to see if it can keep up with HRV humidity extraction in our dry climate. LMK when I can use measurequick on GSHPs. Cheers

[@gordonborsboom7460]

I agree with your doubling of the filters in parallel to reduce face velocities. What is your opinion on sizing for the variance (diversity?) of air flows between heating and cooling when one, say heating, is 50% or more than the other. Say 800 CFM cooling (2 ton) with 1480 CFM heating (80 MBU) an example where heating may be two stage and run times at high CFM may be of short duration. Thanks for you KZbin videos. Your content is much appreciated.

[@measureQuick]

Always size for the max airflow requirements even if it is a short duration. It is only going to provide better filtering on low.

[@HVAC_Tips_Tricks_Calcs]

Great video Jim. Looking forward to more videos info about FFV. One question, does (and if so how) MERV rating affect the calculations? Thanks

[@measureQuick]

It doesn’t effect the calculation, but higher MERV will reduce airflow if the pressure drop across the filter increases.

[@Atheistic007]

The 4” filter with its deep pleats will have a significant increase in area vs the 1” filter. It would be neat to cut the 4” filter open and lay its media out flat and measure it.

[@measureQuick]

The reason for the deeper filters is because they are using a more restrictive, and better filtering media. To get the pressure drop within reason, they need a lot more surface area.

[@Atheistic007]

Yes I agree. Also with a 4 or 5 inch filter with a merv 8 rating the static pressure drop is be relatively low.

[@marcoferreira226]

fantastic stuff, just curious newer style heatpumps with rotary compressors rather than scrolls is there much of a differenance in preformance?

[@mikehenderson_hvac4021]

If using a 4” media, would the the 16x25 be 1600 sq in, then divide by 144 sq in? Let’s say we have 1200cfm then my expected face velo is: 109?

[@measureQuick]

(16 x 25)/144 = 2.777. So 1200/2.777 = 432 FPM. The thickness of the media has no beating on face velocity. I thicker media results in a lower pressure drop due to the extended surface area. It is often required to use more restrictive medias.

[@staticpressurenerd5182]

The MQ lab is basically HVAC Mecca

[@jaysonhines1]

Those TZOA monitors are awesome. Who is selling them?

[@measureQuick]

There is a link to the meters below. TruTech Tools. They are substantially less expensive too if you buy them in bulk. I have been working with them for a little over a year, it is a solid product that is continually improving. Its slick that they can do over the air firmware updates.

[@frankgall6]

Me lol

[@HVACRTECH-83]

Info I'm looking for for a long time now is why can a geothermal (water scource) heat pump run in at such low temps on the water side? For example, I work for school system with these heatpumps in every classroom, the geo water loop temp rite now is low 50s and even though most units are in heating mode rite now in Connecticut, some are running in cooling when needed with those low water temps. There's no defrost or any low ambient type controls on these types of systems so how can they run like this? How is it different than say running your air cooled split ac system at home when it's like 52 degrees or lower outside. These units all have lp switches but the pressure doesn't get low enough to trip them , I'm sure if the water temp was low enough it would trip but not sure how low that temp could be. There's no videos teaching us about these types of systems and they are everywhere these days. Any chance you could do an in depth water scource heat pump video? I'm sure it would help so many of us. Thanks for all your great videos I've been watching you for a couple years now. Keep it coming

[@gordonborsboom7460]

Water holds much more heat energy than air at the same temperatures, so extracting the same wattage of energy from water results in a smaller change in temperature as it passes through the water to refrigerant heat exchanger. You could absorb heat from the water without dropping it to the freezing point. This is why there is no defrost cycles. Air source HP with, say a -20°F temperature change across the outdoor (52°F outdoor air temps) coil would bring it to water freezing temps, building ice on the outdoor umit and requiring a defrost cycle. This doesn't even cover the fact that the outdoor unit would require a temp below freezing to allow heat to move from the air to the coil to get the -20°F change. These numbers are just for illustration only to convey the differences, I hope.

[@HVACRTECH-83]

@@gordonborsboom7460 thanks but I'll wait for Jim to answer hopefully. I'm thinking you don't understand my question fully. I was referring to units running in cooling for this specific question, condensing temp would be closer to 70f minus subcooling which would be much lower head pressure than normal,which will cause even further problems indoors in the evap with very low pressures and freezing temps most likely unless your house is like 100f and dry. I'm not sure exact numbers since I've never run a residential system in cooling in low ambient without system being designed for it with head pressure control, so I may be a bit off. But in heating mode like I think you were trying to explain, I understand how an air cooled hp in heat mode works and I understand defrost and why it's needed. I think your a little confused with your numbers and understanding of how the outdoor unit functions in heat mode ,or I'm misunderstanding what you wrote. Either way,the first paragraph you wrote may have been an answer I was looking for,I'll have to look into it a bit further. Thanks again

[@frankgall6]

Why does my measurequick not look like that? I’ve asked on instagram multiple times but haven’t gotten an answer about spots for the live training.

[@staticpressurenerd5182]

Jim is running a Beta Version of the updated app… it’s pretty slick!

[@frankgall6]

Do you know when it’s going public?? I remember during the symposium he said about 3 weeks it was supposed to be out.

[@measureQuick]

End of the month Frank.

[@edwardjanowiak]

Robin is a pretty awesome person but if she actually has you dusting she went up another 10 points in my book.

[@williamlongo4819]

Hello Jim. Can you tell me what the max CFM’s I can pull through a 3/8 hose and 1/2 inch hose with valve stems removed and connecting condenser directly to the vacuum pump? Thank you. Bill

[@measureQuick]

It depends on the hose length but typically 2 CFM for 3/8” and 4 CFM for 1/2” and 16 CFM for 3/4”.

[@coldfinger459sub0]

Thank you this video with the math and explanation about filter face velocity ,depth , MERV difference in relation to static is much needed. Maybe now I won’t have people telling me I’m killing customers blower motors when I use MERV 16 filters 5” deep with 200 face velocity. And I install a Magnehelic on the filter housing with a felt pen line I add to tell the customer when it’s time to change the filter.

[@measureQuick]

.1 - .2 drop is ideal for filters. If you have that you are golden.