Looking for filter suggestions

What kind of filters are you using in your setups? I'm dealing with a specific issue: I've got a 100cm x 100cm opening to cover, so what kind of filter or alternative material would you recommend?

Mostly in my country they use inexpensive polyester, polyester filter fabric or polyurethane foam. The thickness is selected based on your specifications. Just because of one filter you shouldn’t look for a reduction in price; I think they will sell you a ready-made filter in any store that sells products for ventilation and air conditioning.

https://www.mcmaster.com/2122K181/ 40 inches by 60 inches five merv

This doesn't restrict airflow too much? What do you think about https://ebay.co.uk/itm/166400270240

best thing is test it out. looks like it should be okay some protection but decent airflow.

I can't give you advice because I haven't seen your ventilation system. It’s easier for you to buy several pieces of filter material of different thicknesses at a hardware store and test it on your mining rig. I advise you to then have 2-3 filters, so that while you are cleaning or servicing the first filter, you will have a quick replacement.

FP91G, philipa What do you think about using only the fans from the ASICS to draw in new air from the polyester filter? I have 7 miners in a 1mx1m box, with one filter at inflow end, other end open no filter(outflow) Or should I use dedicated fan to push/pull air through filter? In the past, I ran my ASICS without filter... Now my setup has changed and I have cleaned my machines, I want to use a filter going forward.

air in >>> filter >>> fan >>> machines >>> air out you may avoid the exhaust fan. but often air in >>> filter >>> fan >>> machines >>> fan >>> air out is needed due to filters restricting air flow. its always an issue with filters as they all restrict air flow. but dirt and filth needs restriction especially if you are in a dirty city with a lot of air pollution

The most important question, what is beyond that hole? Is it another room, an open space, is the hole pointing outside and you live in a dusty areas or a wet one or in the middle of nowhere with clean air and no small particles floating around? A fan will definitely be needed and you might need an additional or more powerful fan if you need a high density filter just to suck the air in, my opinion just grab the most affordable  sheets of filters you have in the nearby store and if one doesn't do the job (highly unlikely) you can add another 8mm one on it! Also, just as Phil recommended don't go over 5 on merv scale, you're not fighting bacteria or mold I assume?!? Definitely, also don't forget to take a look now and then at that filter, if you're in a really dusty environment it might need cleaning or you're going to have it restrict all airflow and overheat all the setup.

Was hoping to avoid, but your prob right... Thanks Input and output holes both lead to outside. no mold filter needed, and yes id rather double/treble up etc. hopefully I can get away with just the input fan after the filter before the asics... As for the exhaust fan, why should we need one? we have the fan + asic fans both pushing in that direction.

very hard to answer this. but it is like a balancing act. calculating  what you need can be hard. once you toss in a filter the balance alters. the distances between the exhaust fans and the outside of the room may be so close that no extra fan is needed.

Very close to outside, Less than 2 meters from Asics

may work may not.  the heat from the fans will tend to diffuse and may or may not dump out of the room. Trial and error is your friend here. Just remember you may need an exhaust fan or may not. and if they are 1 foot from the outside rain may hurt them

The heat cannot go back into the input-air-room, each miner is sectioned off so that exhaust can only go outside. Reverse humidity could be an issue but I would assume the exhaust would keep it from backwards direction to the rigs Uk is always cold, even in the summer, rn its 7 degrees Celsius

I find this interesting. Is this how most people approach a cold room / hot room setup? I've done 6 now, and I've never used fans for the air in. All my setups are passive on the air inlet, I only use fans to extract as follows: air in >>> filter >>>  machines >>> fans >>> air out Is there an advantage to 'pushing' the air through the farm instead of 'pulling' it out? My farms work brilliantly this way, and by having fans at the air outlet point, and 'pulling' more CFM than the miner outlet fans, the negative pressure ensures no hot air lingers or buffets in the hot room.

As for filter material, this is what I use (I am UK based also): https://sprayboothserviceandfiltration.com/collections/frontpage/products/https-spray-booth-service-filtration-myshopify-com-product-filter-extraction-secondary 20mm G4 spray booth filter

air in is not needed all the time.  for our farm the space for fans was very limited. We could not get proper flow without using input and exhaust fans.

I must admit I just 'winged' my first setup (but also following advice from yourself and Mikeywith) - it worked very well. I took the total CFM of all my miners, added 20% and used that figure to determine the size / power of the extractor fans I would need. This setup has been flawless and I've copied it throughout all my other hot/cold setups.

my issue was room shape a rectangle and I need air flow to make a 90 degree bend fan exhaust <<<                    gear gear gear gear                          ^^^^                      intake fan

It's a little bit more complicated than it seems, but in general, you don't need in-fans, in fact, for most designs, in-fans will create more harm than good, there are two important components to perfect cooling, air volume and air velocity, injecting air at the fast speed into the farm would cause air turbulence. You should also know that the type of intake matters, louvers or not(air coming in through louvers has higher FPM), filtered or not, so it's a lot of things to consider to reach perfect cooling, the most important factor is your static pressure around the fans, the CFM labeled on all fans is usually reference against pressure of 0 PSI, the higher the PSI the less the CFM, enough high static pressure could make your fan spin without moving the slightest bit of air. I have probably not talked much about airflow for years, and whatever posts I wrote before were basically based on my own personal experience, they do the job, but probably far from perfect, I have learned too much over the years through educating myself more about HVAC, Airflow, Air pressure, and all related subjects, the size of the farms I set up (either for myself or for clients) has also changed, but I can give you one general rule that would be 90% perfect without going into many details. Do 0.1 square meter intake and 700 cubic m/hr per miner US folks do: 1 sq ft intake and  400 cfm per miner For 10 miners you would do 1 square meter (just a window in the wall sized 1m by 1m) and 7000  cubic m/hr exhaust fan US folks: for 10 miners you would do 10 square feet and 4000CFM Credit goes to Aviral of altairtech who gave me this simple rule which works perfectly.