My strange equipment room

[Mesozoic]

Well, I just discovered that when the 110 cfm exhaust fan is running, there is airflow on a secondary 5" round duct stub that was uncapped in the same room. The fan and the 5" duct are tied together at Y which then feeds a 7" exhaust tube out of the roof. I think that the exhaust fan airflow was taking the path of least resistance and circulating air it had sucked back into the same room via the 5" duct. Capping it off may have helped considerably.

Thinking that perhaps I could install a 5" duct fan to the spare stub for additional exhaust performance?

 

[cvairwerks]

Found some numbers for you... Industry standards for rough calculations are 1500 btu/h per horsepower and 1500 btu/h for aftercoolers. So by that, you are inserting an average of 15k btu/h into your room, just from the compressor. Not going to cool it down much with a couple of fans under heavy air usage.

 

[Mesozoic]

Found some numbers for you... Industry standards for rough calculations are 1500 btu/h per horsepower and 1500 btu/h for aftercoolers. So by that, you are inserting an average of 15k btu/h into your room, just from the compressor. Not going to cool it down much with a couple of fans under heavy air usage.

Yeah, it's not a great situation at all. Some serious airflow through that room is what I need, but can't see how I can do that without stepping up to some serious business, like 900 cfm exhaust.

I found this in 5" duct sizing: https://www.homedepot.com/p/VENTS-U...In-Line-Exhaust-Duct-Fan-TT-PRO-125/204817010

 

[wyliesdiesels]

and whats the reason you cant cut a whole in the wall and put in a window shaker AC unit?

 

[cvairwerks]

900 scfm will require bumping up to a 10” duct or larger....

 

[mike93lx]

Sounds like you either need another 2 ton mini split or to get the compressor out of the room.

LOL at the earlier thought that 110cfm was overkill. That barely clears out a decent size bathroom

 

[Mesozoic]

Sounds like you either need another 2 ton mini split or to get the compressor out of the room.

LOL at the earlier thought that 110cfm was overkill. That barely clears out a decent size bathroom

LOL, I can see where the calculation shows that 108 cfm would change the air in that space 15 times/hour, but that's obviously not a calculation that will work for such an instant thermal load.

I've got a 7" duct to the roof jack that splits into a Y-fitting that currently goes to the 110 cfm exhaust fan and an empty 5" tube. I've ordered an inline duct fan to mount to that tube and am hoping to get at least another 200 cfm out of that (rated for 286 cfm @ 0" static). With a 1'x2' grille on the door, maybe it will work for evacuating the heat. An honest 300 cfm of airflow out of that closet will help, for sure. Of course, I've been using the compressor in the worst case scenario as well: 100F ambient heat.

The reason I can't use a wall-mounted AC unit is because the closet is inside my garage and does not share an outside wall. I got a thermostatic switch as well, so will see how it goes once all the parts arrive.

 

[wyliesdiesels]

LOL, I can see where the calculation shows that 108 cfm would change the air in that space 15 times/hour, but that's obviously not a calculation that will work for such an instant thermal load.

I've got a 7" duct to the roof jack that splits into a Y-fitting that currently goes to the 110 cfm exhaust fan and an empty 5" tube. I've ordered an inline duct fan to mount to that tube and am hoping to get at least another 200 cfm out of that (rated for 286 cfm @ 0" static). With a 1'x2' grille on the door, maybe it will work for evacuating the heat. An honest 300 cfm of airflow out of that closet will help, for sure. Of course, I've been using the compressor in the worst case scenario as well: 100F ambient heat.

The reason I can't use a wall-mounted AC unit is because the closet is inside my garage and does not share an outside wall. I got a thermostatic switch as well, so will see how it goes once all the parts arrive.

Dont understand why you need an outside wall.

Ive used 2 window units mounted in office wall cavities that blew into the same shop without issue.

I also did some wiring for an insulation contractor whom had dual window units mounted in an office space, both of which blew out into the wood working shop. Again, no issues...

 

[Mesozoic]

It's a residential garage attached to the main dwelling, so don't want to mount a wall unit in there. Here's a couple of snaps to illustrate the situation.

 

[bad_idea]

How about a fan installed in the door in place of the grate to pressurize the room? That would push the extra air in the room and out that 5" duct (and basically turbocharge the 110 cfm exhaust fan). Wire the 'door fan' to the pressure switch on the compressor with a relay to come on when the compressor comes on.

Also, you said the shop is climate controlled? I would dump the exhaust from the compressor room back into the shop up high. I think it would be better to dump those btus into the shop than to force the building to **** outside air into the building to replace that air. Especially considering you are in Arizona! Would also assist in moving air through the compressor room as you are not putting the building under negative pressure when running the exhaust (think trying to **** the air out of a coke bottle).

 

[mike93lx]

For less than $200, you can get a 1600 cfm fan with some ducting. That could be a reasonably cheap way to figure out if ventilation is enough.

https://www.globalindustrial.com/p/...ion-fan-12-inch-with-16-feet-flexible-ducting

 

[510ebl]

I believe you already posted your solution; an air handler added to your existing mini split. You said there are two additional ports? Or did I misread?

If you are running a D/A sander, the last thing you want (as you know) is mixing server room air with the garage.