TD150 / filter question

[JohnnyPotseed]

There's an argument on another site about a CAN 33 vs CAN 50 filter on a S&P TD150. Common sense would tell me the CAN 33 is the right fit for a TD150, since the CAN website recommends 3 fans for a CAN33 filter. These fans range from 130-230 CFM. The TD150 can be set to 210 cfm on low so it would be perfect for a CAN 33 filter in my head.

Everything was great, until I had to dig up an argument on the issue. Basically they say- since a CAN50 filter has more surface area, it has less static pressure.

This one guy is even taking fan CFMs and dividing it by "Max airflow cfm" as stated in the filter specifications on CAN website. He claims fan CFMs divided by "max airflow" of given filter will give you static pressure ratings. I'm skeptical on the accuracy of this formula, but it kind of works if the static pressure ratings are correct. (in favor of the CAN50) ... REGARDLESS

The minimum airflow recommended for CAN 33 is 100 cfm, while it is 210 cfm for the CAN 50. If the CAN 50 "produces less static pressure", why is the minimum airflow recommended higher? A td150 set on low at 212cfm would barely meet the minimum airflow for a CAN 50, while it seems to me it would be in the sweet spot for the CAN 33.

Furthermore, recommended fans on the CAN website for the CAN 50 range from 3- 570cfm!! The TD150 is 290cfm on high, so WTF?

Also- im seeing reports of td150s running 33 filters and some even smaller, have yet to see anything bigger though.

With all of this being said, the thread on the other site came to the conclusion that the 50 would be better than the 33, and the 66 even slightly better than both. Hell they even almost have me convinced.. a bigger filter with more carbon = less workload of your fan ... really??

I hope my my thoughts are coherent, as it was my way to ask... WHATS THE GOOD FAN FOR A TD150s LOL without sounding like a jackass.

I'm especially interested in anyone with knowledge of CAN filters in combination with S&P TD silent series fans. Shit come to think of it, this whole argument was aimed toward the mixvent line of S&P-- I think the silent series is newer with better ratings but the same principals should apply.

Thanks for any insights.

- a man with airflow issues.

 

[IndoorHaze]

Don't get all tangled up in techno babble. Pick out a filter that is rated for your CFM requirements or greater. Obviously bigger will equal less air resistance, but at some point you reach the point of diminishing return on investment. I run a TD 100X with a tiny Phresh filter and get plenty of airflow on low setting. I wired it with a relay controlled by a Win100 thermostat that will kick it to high if needed. So far it's never tripped.

 

[JohnnyPotseed]

Thanks. You confirm the principal of bigger filter= less workload (to a certain point)- so I will try out the can 66 on the td 150s. I'm just trying to avoid reaching that "point of diminishing returns." You say diminishing on investment, but I suspect there is also a point of diminishing returns with performance.. bigger=better airflow, bigger=better airflow, bigger= BOOM too much.. fan cannot handle static pressure...

Then again if static pressure is dropping the bigger we get then that should never happen.. .. I will give reports on performance for the CAN 66 with TD150s for future reference as there are no current examples.

 

[IndoorHaze]

....I suspect there is also a point of diminishing returns with performance.. bigger=better airflow, bigger=better airflow, bigger= BOOM too much.. fan cannot handle static pressure...

Bigger will always lower the load on your fan, and increase the load on your wallet. I would rather take that extra $100 and spend it on something useful.

 

[JohnnyPotseed]

Are you suggesting the CAN 33?

 

[JohnnyPotseed]

Pick out a filter that is rated for your CFM requirements or greater.

All the CAN 33 says is "Max scrubbing 400cfm @ .1sec contact time" WTF is @.1 sec contact time? Is this just saying don't pull more than 400cfm through the filter?

Also the td150s has a chart of CFM drop compared to static pressure levels. After 15ft of ducting, I can figure out the static pressure. I don't know how to add the filter in to the equation. Trying to determine if a larger fan is needed to meet air exchange 3-5 times per minute.

That's why I was stuck on that guys formula for figuring out static pressure between a filter and fan.

 

[IndoorHaze]

Are you suggesting the CAN 33?

IMHO that filters specs bracket your fans CFM capability pretty nicely.

 

[IndoorHaze]

Again, try not to get bogged down in the minutiae. That .1 sec contact time is just their labs way of quantifying test criteria. Go with the CFM rating and you will be fine.