Air conditioning a conex

[Bluedog225]

I need to air condition my conex before the summer heat to keep the batteries cool. I’ve already insulated it pretty well.

I thought I was going to run my dual hose Midea portable air conditioner hoses out the floor. But it turns out the hose will not reach. Darn it. I’m going to look into extending the hose. There is no factory extension. I’ll have to buy another hose and kludge together a patch. Not optimal. There will be a hit to efficiency but I’m ok with that. The replacement hose is about $80.

In this regard, I could try to build a box out of duct board and create a diy extension for the original dual hose intake/exhaust. This might be a good option as well.

Or I can vent the dual hose out the back wall of the conex. Though I hate the idea of cutting a hole in the conex side. It seems like a larger security breach (wall versus underneath) and allows for the possibility of water intrusion. I’d need to build/buy some sort of cover.

Finally, I could install a mini spit. This was not in the plan but I can give it a shot. I don’t know if I can have a compressor up on the conex outside wall and run the refrigerant hoses down the wall and back up into the conex. That is, making a “U.” Or do I need to put the compressor on the ground? There are some flooding issues. Or do I need to put a #” hole in the conex wall for this as well?

Anyway, those are the options so far. Though I guess I should add the possibility of a regular or U shaped window unit hacked into the side or a roof mount unit. Neither of those seem ideal.

Any thoughts welcome.

 

[HighDesertOffgrid]

Finally, I could install a mini spit. This was not in the plan but I can give it a shot. I don’t know if I can have a compressor up on the conex outside wall and run the refrigerant hoses down the wall and back up into the conex. That is, making a “U.” Or do I need to put the compressor on the ground? There are some flooding issues. Or do I need to put a #” hole in the conex wall for this as well?

No insight on the Midea. Creating a trap in refrigerant lines could starve the compressor for oil. Some professionals say that will shorten the life of a minisplit. I would opt for the minisplit mounted higher on the wall and another 3" hole.

 

[parksnorris]

I need to air condition my conex before the summer heat to keep the batteries cool. I’ve already insulated it pretty well.

I thought I was going to run my dual hose Midea portable air conditioner hoses out the floor. But it turns out the hose will not reach. Darn it. I’m going to look into extending the hose. There is no factory extension. I’ll have to buy another hose and kludge together a patch. Not optimal. There will be a hit to efficiency but I’m ok with that. The replacement hose is about $80.

In this regard, I could try to build a box out of duct board and create a diy extension for the original dual hose intake/exhaust. This might be a good option as well.

Or I can vent the dual hose out the back wall of the conex. Though I hate the idea of cutting a hole in the conex side. It seems like a larger security breach (wall versus underneath) and allows for the possibility of water intrusion. I’d need to build/buy some sort of cover.

Finally, I could install a mini spit. This was not in the plan but I can give it a shot. I don’t know if I can have a compressor up on the conex outside wall and run the refrigerant hoses down the wall and back up into the conex. That is, making a “U.” Or do I need to put the compressor on the ground? There are some flooding issues. Or do I need to put a #” hole in the conex wall for this as well?

Anyway, those are the options so far Plumber in Maui. Though I guess I should add the possibility of a regular or U shaped window unit hacked into the side or a roof mount unit. Neither of those seem ideal.

Any thoughts welcome.


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I need to keep an 8x40' steel connex cool that is filled with electrical components. We call this unit the Drive house. When the unit is running at 100% capacity, we're drawing 2.1 megawatts of power and it all flows through the drive house and then to the other units. There are multiple computers, PLC's, 12 heavy duty VFD's and 42 AC drive units all generating heat. Our process generates a lot of fine dust so we have to keep the drive house closed up. (sorry for vagueness, there's an NDA)

Since this is a prototype unit, we are learning some things the hard way. No one considered heat build up in the drive house. On a heavy overcast 55° day the temp inside the drive house was hitting 110°. We installed the biggest residential portable AC unit available for purchase in Alaska which was 10,000BTU. On the same 55° overcast day with the portable AC, the drive temp stayed around 75°. Then the sun came out. On a full sunny day at 70° OAT the drive house temp exceeded the range of our thermometer which tops out at 120°. The VFD cabinet got hot enough to cause several VFD's to shutdown with overheat faults. I think the VFD high temp shutdown is 160°
We were fortunate that the unit's first job was in a coastal town that gets 70" of rain and 365" of snow annually, so we rarely saw sunny skies.

Our innovation team (the group with all the engineers) has tasked me (the unit operator who knows nothing about sizing HVAC) to find a cooling solution before our next job. Our next job will be in a region that sees a lot of sunny days and much higher OAT's (80-100°).

I did the guy thing and googled "portable industrial cooling", clicked on the largest unit in the listing which was 7.5 tons. The unit will fit in the drive house and 480v 3ph is available. A bargain at $****.
Thought I was done, then a buddy says, "hey, its not good to have too big of a unit either" Great!

So, how does a fellow who sucks at math and doesn't know the wattage of 99% of the heat generating gadgets figure out the proper size A/C unit to buy? If you, (the professionals) got a call from a customer (the idiot) describing the above scenario, would you be able to guesstimate the tonnage needed?

I've also reached out to a couple industrial cooling rental outfits but waiting to hear back.

Thanks.

 

[JoeHam]

Regarding insulation, a thread on the forum years ago discussed how it was more efficient to insulate the exterior of a connex as opposed to the interior. It also maintains the limited interior volume/space.

Seems like that will be a piece of the puzzle for you.

Unfortunately I’m not versed in the HVAC calculations you’re looking for.

 

[JimP]

Well, if you know how much power is being consumed by and produced by what is in the conex, the difference is the waste heat. Convert kWh to btuh. We can mostly ignore ambient temp if ambient plus some delta is the k for internal temp. Then solar gain. Instead of calculating it, I’d shade the comex, preferably with solar panels

 

[Bluedog225]

“We installed the biggest residential portable AC unit available for purchase in Alaska which was 10,000BTU.”

That doesn’t sound right.

 

[Dave911]

All of those VFDs have specs that say how many btus of heat they can create. Add up all the btus.
Paint the conex white for less heat gain. Look up heat load calcs for the solar heat gain for that conex. Add it all up. Thats what you need in AC Btus If your operation isnt stupid dusty, install blowers with serious filters and just blow air through the conex.