Return Air Filter for Mini Split Ac ?

[Perry Holbrook]

Just installing the mini split in the new shop. Looks to me like the return air filter is not adequate for a woodworking shop. Even with the best of dust collecting there is still some fine dust in the air. In my last shop, I had a window unit ac and just attached some filter media over the intake grill.

Just wonder what those of you that have a mini split are doing to keep the coils clean.

Thanks

[Jim Becker]

You can just clean it frequently or build a structure like Jay Bates (on YouTube) did to add additional filtration. You'll want that large enough so that it's much larger than the units actual intake area since the filters will at least slightly restrict air flow. In my previous shop, I just cleaned my unit frequently and it lived above the CNC which absolutely was a dust producer. In my new shop, I have not yet decided on how I will handle this.

[Chris Parks]

Just installing the mini split in the new shop. Looks to me like the return air filter is not adequate for a woodworking shop. Even with the best of dust collecting there is still some fine dust in the air. In my last shop, I had a window unit ac and just attached some filter media over the intake grill.

Just wonder what those of you that have a mini split are doing to keep the coils clean.

Thanks

I doubt you have adequate dust collection if you can see visible dust in the air.

[Jack Frederick]

A part of your service on the mini is to not relay simply of the mesh filter. The finest dust will get into the coil and onto the small diameter fan. As you live in a humid area that can be a problem. Understand how to clean the coil and the fan periodically. Also, as you are doing this install make sure that the drain line is run with no traps. Adding the external filter may work, but it may also restrict air flow. When I was with Fujitsu we always said no on the box filters.

[Michael Schuch]

I have installed 2 mini-split systems with a total of 4 head units in my house. The head units really need to be cleaned pretty thoroughly at least once a year. I can't imagine the head units holding up for very long in my dusty shop.

I have considered one of the concealed duct mini split head units for my shop instead of the wall mounted unit. With the concealed duct head unit I can do the ducting the way I want to with as fancy and large of a filter array as I want on the intake side of the duct unit.

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https://hvacdirect.com/ductless-mini-splits/single-zone-ductless-mini-splits/filter/concealed-duct.html?adgroupid=73817094661

My concern is if the blower in the ducted head unit is powerful enough to pull air through a pretty fine particle filter which got me thinking of a whole house electronic / electrostatic filter with 3 or 4 of the regular AC air filters in front of it. I would put the 3 or 4 filters side by side to increase the air intake area 3 or 4 times the normal filter area minimizing the accumulated flow restrictions from saw dust.

I am usually in my shop during the weekends as I work during the week like most. I wonder how efficient a mini split will be if I only want it running during the weekend? The mini splits in my house run 24 x 7 and only change their cooling power based on the internal temperature. Which makes me think a powerful through the wall all in one AC unit might make more sense for my shop?

[Michael Schuch]

You can just clean it frequently or build a structure like Jay Bates (on YouTube) did to add additional filtration. You'll want that large enough so that it's much larger than the units actual intake area since the filters will at least slightly restrict air flow. In my previous shop, I just cleaned my unit frequently and it lived above the CNC which absolutely was a dust producer. In my new shop, I have not yet decided on how I will handle this.

I like his approach:

https://www.youtube.com/watch?v=S_Li3Z7F8tE

https://www.youtube.com/watch?v=takupOBctjA

It is kind of what I was envisioning but I was thinking of hanging it on my shop ceiling using the concealed duct head unit instead of on the wall with a conventional wall mount head unit.

[Jack Frederick]

The concealed units are more of a pain to clean than the wall units in my experience. That said, going into it with that understanding you can position the unit to make it easier to service. Be very careful in selecting these units. The original concealed unit we introduced could handle no more than about 12’ of duct due to very low static pressure capability. that precluded any additional filtration. I have not kept up with the changes in specs on these units, but make sure you pick the right one.

[Greg Funk]

The concealed units are more of a pain to clean than the wall units in my experience. That said, going into it with that understanding you can position the unit to make it easier to service. Be very careful in selecting these units. The original concealed unit we introduced could handle no more than about 12’ of duct due to very low static pressure capability. that precluded any additional filtration. I have not kept up with the changes in specs on these units, but make sure you pick the right one.Some of the Mitsubishi ducted units are intended for higher static pressure and they also offer some external filter boxes or you could roll your own.
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[glenn bradley]

I just stuck some high MERV pleated filters on top of the inlet area. They catch a lot of stuff and are easily tapped clean enough for multiple uses. Obviously good collection at the source will effect how workable this is. If you have a lot of stuff flying around in your air I would do something more sealed and formal. I would rather put my effort toward better gathering at the source. I figure if my mini-splits are gathering too much spoil then so are my lungs.

[Kyle Stiefel]

This is what I ended up doing but the great irony is I haven't powered it up. I don't have electricity yet to the shop, long story.

I installed one of the the Mr. Cool DIY units. And to answer the next question this off angled, asymmetric location is ideal for the shop but not as ideal for air flow. Time will tell once I power up the shop. It only takes a few minutes to cycle the filters and few more minutes to take the entire thing off to clean the unit. Not fine woodworking, haha

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[Jim Becker]

Looks pretty darn good to me, Kyle!

[Perry Holbrook]

Thanks Kyle, that’s pretty much what I had in my head when I ask the question.

[Greg Funk]

This is what I ended up doing but the great irony is I haven't powered it up. I don't have electricity yet to the shop, long story.

I installed one of the the Mr. Cool DIY units. And to answer the next question this off angled, asymmetric location is ideal for the shop but not as ideal for air flow. Time will tell once I power up the shop. It only takes a few minutes to cycle the filters and few more minutes to take the entire thing off to clean the unit. Not fine woodworking, haha
I don't particularly care about the AC but I'd like to see some more pictures of your shop!

[Kyle Stiefel]

I don't particularly care about the AC but I'd like to see some more pictures of your shop!

Once I finally get it finished, 3 year process but in the final stretch. I did have a piece of the puzzle arrive a month ago to the freight terminal for pick up as tractor trailers don't come to my house. Unfortunately, the shipping company roached it and had to send it back. I have not had great luck over the last several years with freight except for SAIA but this time they failed me. So hopefully in a few months I will try again for a pick up.

If you can't make dust it just isn't a shop, haha, so the search for the elusive electrician will continue as my prior was supposed to be back in March but has ghosted me as there is likely far more lucrative work for him elsewhere. I like to tackle many things myself but I leave the electricity to the pros.

[Bryan Cleveland]

Just installing the mini split in the new shop. Looks to me like the return air filter is not adequate for a woodworking shop. Even with the best of dust collecting there is still some fine dust in the air. In my last shop, I had a window unit ac and just attached some filter media over the intake grill.

Just wonder what those of you that have a mini split are doing to keep the coils clean.

Thanks

I’ve had my Mitsubishi mini-split 6 years now and all I did was buy one of those blue 3m cut to size filters at Lowes. Cut a strip and it sits right on top of the inlet. Before the blue plastic mesh filters. Works well too.