What airflow to expect from extractor filter & fan combo?

[NorthernCosmos]

I have a 2x4 tent with an 100mm extractor system consisting of a Blauberg Turbo-E 100 rated at 187m3/hr (110cfm) and a Hy-Filter rated at 250 m3/hr (147cfm). The filter has the supplied pre-filter jacket around it. Less than 1m of alu flex tubing is used with two slight bends. This should be a bog-standard setup, and more than is recommended for the tent. The exhaust is in the room, right outside the tent.

The exhaust from this is barely noticeable with the fan at full speed. If I stuff my nose into the exhaust I can feel warm air in my face - almost nor more than opening a top vent and letting the convection move the air. A piece of string or a piece of paper held in front of the exhaust will not flutter, behaving as if there's no air flow at all. If I wrap paper around the filter, the paper falls right off as if there no suction at all.

I run a 300W LED light there, dimmed to c.a 225W (Mars Hydro TSL 2000). The tent sits at almost 28°C (82.4°F) at mid-plant height at daytime and the ambient temperature is ca. 18°C (64.4°F). Initially I would've thought that there would be a noticeable stream of air from the exhaust and a reasonable cooling effect. Is the barely moving air described above what I can expect from this extraction system?

Edit: changed thread title to be more precise.

 

[Chris Scorpio]

I always say bigger is better

I run a 6" Cloudline in my 2x4, ran less than half speed, worked fantastic, much better than the hurricane fan I used before it, and much quieter

I now run it pulling from my 2x4 and 4x4 at about 2/3 speed

Love it

 

[NorthernCosmos]

Yes I agree, bigger would be better (not least for noise), but in theory even this system should be overkill for the 2x4 tent, so that's what I got... BTW I have all three bottom intakes open on the tent (a Mars Hydro 2x4).

How much air did your system exhaust? Enough to feel a breeze on your face or for a paper or string to flutter or dance about? I haven't got any experience with this sort of ventilation so I have no idea of what to expect.

 

[Chris Scorpio]

I can put my hand up to the exhaust and feel a pretty strong pull out of the tent

Less open flaps will increase the draw I believe

 

[NorthernCosmos]

I can hardly feel anything when placing my hand right in front of the exhaust; it's mostly just a change in exhaust sound.

OK, I'll pick this extractor system apart for inspection, although I can't imagine what might be wrong (if anything...) with this being such simple stuff.

 

[Chris Scorpio]

Did u pull the fan, no duct at all, and test the draw just plugged into the wall

 

[NorthernCosmos]

Not yet - I'll report here as soon as I have done a tear-down. It could be normal, with the carbon filter slowing down the air stream a lot more than I anticipated.

 

[NorthernCosmos]

I've now disassembled and inspected the extractor system.

The first step was to just disconnect the filter. And wow - the fan makes a gale at the exhaust, my hair flapping in the wind. I estimate the airflow to be just 5% (trying not to exaggerate) of that with the filter attached.

Then I took off the pre-filter, which was completely clean except from calcium dust. There are cat hairs in this house, and I pick some off the buds every time I tend to the plants, but I couldn't spot a single hair on the pre-filter. There was no detectable change in airflow with and without the pre-filter.

Next, I took the filter outside and gave it a good shaking and spanking, as in tapping it vigorously on all sides and shaking it so the carbon pellets were rattling around and puffs of calcium dust (form the pre-filter) was seen. When I reattached the filter the airflow was improved, indicating that a bit of shaking up helped. However the improvement was slight, I estimate the flow to be 10% now.

The filter is part of the "top-quality" extraction kit that I bought (info here). Of course the manufacturer and supplier boast about how very good the filter and fan is. The filter rating of 250m3/hr should give a fairly unrestricted flow, right?

So what I'm seeing is that the carbon filter severely restricts the airflow, almost stopping it dead. say at best 10% of the unrestricted fan capacity comes through. Is this normal? Are there extreme differences in the restriction of different filter brands? Is this filter junk? What would you folks do in this situation?

 

[TurboBucket]

I've now disassembled and inspected the extractor system.

The first step was to just disconnect the filter. And wow - the fan makes a gale at the exhaust, my hear flapping in the wind. I estimate the airflow to be just 5% (trying not to exaggerate) of that with the filter attached.

Then I took off the pre-filter, which was completely clean except from calcium dust. There are cat hairs in this house, and I pick some off the buds every time I tend to the plants, but I couldn't spot a single hair on the pre-filter. There was no detectable change in airflow with and without the pre-filter.

Next, I took the filter outside and gave it a good shaking and spanking, as in tapping it vigorously on all sides and shaking it so the carbon pellets were rattling around and puffs of calcium dust (form the pre-filter) was seen. When I reattached the filter the airflow was improved, indicating that a bit of shaking up helped. However the improvement was slight, i estimate the flow to be 10% now.

The filter is part of the "top-quality" extraction kit that I bought (info here). Of course the manufacturer and supplier boast about how very good the filter an fan is. The filter rating of 250m3/hr should give a fairly unrestricted flow, right?

So what I'm seeing is that the carbon filter severely restricts the airflow, almost stopping it dead. say at best 10% of the unrestricted fan capacity comes through. Is this normal? Are there extreme differences in the restriction of different filter brands? Is this filter junk? What would you folks do in this situation?

Simple your fan sucks. Some fans work well under high pressure operation, most do not. Your filter is too small and was also full of "calcium dust" so it choked the little fan out. A properly sized filter will reduce advertised fan airflow by up to %50. Poorly sized even more so. Hyperfan is the only Brand I know of that actually publishes fan/filter combo airflow charts.

I'm assuming you use an ultra Sonic humidifier somewhere? Those things are murder on carbon filters if you use hard water. The dust clogs all the air space in the prefilter and carbon bed reducing and then stopping airflow. Wicking humidifiers are more filter friendly.

Sellers recommended sizes are always too small. I use 8"x24" filters in my 4ftx4ft tents

 

[NorthernCosmos]

I do have hard water, so there's some calcium dust from my atomizing humidifier. But even so, the filter in itself seems way too restrictive - there never was much of an exhaust. That Blauberg fan comes highly recommended, with lots of happy users and is allegedly supposed to work well in a high pressure system - I did quite a bit of research prior to buying, watching videos and reading threads and articles; it felt like a safe buy.

I didn't see calcium dust on the carbon pellets, but the pre-filter was quite dusty, and as mentioned a shaking up of the filter canister resulted in ca. twice the airflow.

My conclusion so far is that this filter is no good. I shall take it out again and REALLY shake it up to see if I can get even more air flow - I can't afford to replace it at this time, so I'll have to make the most of it. If anybody knows of a proper filter test (not just parroting the sellers prose - that's all I've found so far), that tests for airflow, or just have found good filter brands with low restriction, please let me know.

Edit: I may replace this system in the future, or possibly moving it over to a flowering tent when I get into photos, but that is part of a a bigger and more expensive project, probably a year down the line or so.

 

[Edzzed]

I don't have a filter. My fans just expel it out a duct tube to the top of our house. I use two back to back fans. They do not run very long when trying to get temps down. The cloth is just to stop any wildlife from entering the tent. I don't recall the cfm it is supposed to move. 2nd reason for two fans is early stage of growth. One runs on temperature, The other on humidity. Once they grow then I bring in a dehumidifier and run 2nd fan on temps as well.

 

[NorthernCosmos]

Yeah, I'm considering running without the filter now. I can run the exhaust to the above-oven ventilation fan outlet that's already in the room (old kitcen, not in use). I live in the countryside, so the odour shouldn't normally be much of a problem. However there could be "unexpected visitors" - you never know - who might get a whiff of it, so ultimately I want proper filtration for security.

 

[TurboBucket]

I blew mine out with an air compressor. Use a plastic bag or a rag to seal in the inlet and blow air from the inside out.

 

[NorthernCosmos]

Good idea, Turbo - I have a fairly powerful compressor, so I shall give it a whirl! After all, just some shaking and knocking resulted in a doubling (or more...) the airflow.

 

[Virgin Ground]

Did your rh ever get above 70% while running your filter? That will kill it too. Ultrasonics like mentioned earlier will do it as well. I've done it myself.
I don't run carbon until I'm in flower now. Th below or around 60%.I put my filter away after it's been running at a low rh for a few days , blow it out with a compressor and wrap it in plastic until it's time to use again.

 

[nickeluring]

How does your air intake look like?

 

[NorthernCosmos]

Did your rh ever get above 70% while running your filter? That will kill it too.

Yes, it got into the 70s once when I made a wrong humidifier setting, it only lasted for a few hours though. Would that be enough to clog it up? Can't remember there ever was much exhaust flow, but there has to have been more than it is now.

I've seen people saying that you can wash your carbon filter cans in soapy water, dry them thoroughly and they'll be good as new. Sounds too good to be true...

How does your air intake look like?

All three bottom intakes are open in a Mars Hydro 2x4. I reckon that is plenty of intake area at around 1.2 square feet.

 

[Virgin Ground]

Yes, it got into the 70s once when I made a wrong humidifier setting, it only lasted for a few hours though. Would that be enough to clog it up?

Most of me wants to say yes. It's entirely possible.
I've heard of a few people drying them out in their ovens at a low temp for an extended period. They say it works.
Nothing to lose really. May be worth a try.

 

[nickeluring]

All three bottom intakes are open in a Mars Hydro 2x4. I reckon that is plenty of intake area at around 1.2 square feet.

Yes, I agree.

I've got the same size tent as you. I've got a 5" exhaust fan that pulls 360 m3/hr. Even without the filter I wish I had more air flow. I've got the filter mounted in the tent, but disconnected from the fan. I only connect the filter when I know I'll get visitors that I want to hide the smell from.
As it is now I have a good air flow. It'll blow my hair around when standing in front of the outlet. With the filter on my hair will not blow around much. And I also don't like standing there with hot air that smells of nothing blowing in my face. Without the filter I can't help but stick my nose in the outlet every time I pass.
With even more air flow I could lower the temperature in the tent a bit.

 

[NorthernCosmos]

I only connect the filter when I know I'll get visitors that I want to hide the smell from.

A good tip there! I might just do this if I can't sucessfully "treat" my filter to give more flow.

Without the filter I can't help but stick my nose in the outlet every time I pass.

Hey, you're convincing me to run without a filter...