Cooling an equipment room


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Old 04-16-21, 01:22 PM
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Cooling an equipment room

I have some new equipment that I've setup in an old closet/storage room. I was thinking this would be an ideal location because it is a smaller area and would be easier to control the temperature with air conditioning. Thus far I have installed a ceiling vent and put in a portable A/C unit. Before I learned about the two hose systems, I purchased a single hose unit. The A/C is rated as 6,000 BTU (DOE). The room is 5x6. The equipment heats the room to 95 degrees Fahrenheit. The A/C unit doesn't cool it down one bit. Part of the problem I believe is the vent hose, it is not insulated and acts like a damn radiator.

What suggestions can you offer to help cool this space down? There isn't a window so a window unit isn't an option. I had tried to find a calculator to figure out how many BTU it will take to reduce from 95 to 70 but I haven't found one.

Can I get away with a portable unit? What if I put it in the adjacent room and somehow vent the cold air into the room, would that even work without pulling room air to be cooled?

I am trying to avoid a permanent solution like a traditional A/C installation because I don't want the permanency of an outside unit plus, it severely limits my ability to repurpose the room and move the equipment.

What is the minimum number of BTU needed to drop 30 degrees of temperature? Due to the equipment generating heat, I am not sure the room size method is accurate to gauge how many BTU is needed.

Thank you in advance for any help or guidance you can offer.
 
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Old 04-16-21, 06:23 PM
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More info is needed.
"The description "some equipment" does not tell us anything.
Also, you said you installed a vent but this also does not tell us what you have done..

If you are using a portable airconditioning unit it can't be piped
in.
You need to put it in the space then discharge the hot air from the unit to the outside.

 
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Old 04-16-21, 07:06 PM
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What is the size of the room? Is this in a house or office? What kind of construction? (stick framed and drywall?) What rooms are around the room?
 
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Old 04-16-21, 07:06 PM
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The equipment is an industrial 3D printer and a vacuum forming machine as well as a resin curing oven.

I installed an 80CFM ceiling fan and ducted the exhaust hose from the portable A/C unit to the ceiling fan.

My hope was the hot air would be exhausted outside, which it is, but the hose itself is not insulated and being 60 inches, has plenty of length to act like a radiator putting heat back into the room.

The reason I wanted to vent in the cold A/C air from outside the room was so that any heat generated by the A/C unit would be external to the room needing cooling. That room would only receive the cool air.

Why can't this be done? I'd like to better understand why so I can start to focus on ways I can use this A/C in the most efficient way possible. (or return it in favor of something better suited to the environment)
 
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Old 04-16-21, 07:12 PM
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The room size is 6x12.
It is in an office. The building is a newer construction, designed like a ground level only storage unit with every unit sharing the same length, just varying widths. It appears to be drywall/frame construction with an aluminum roof.

 
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Old 04-17-21, 04:42 AM
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A single-hose portable A/C is not going to cool the room as you have noticed not because of the hose (not that it helps) but because you are creating negative air in the room. When the A/C is running it is using the room air to cool the condenser coil. That is the same room air the machine has already cooled. That air is ejected outside is then replaced by the air in the office. This is very inefficient.

A two-hose portable A/C has one hose for intake and one for exhaust. This is a "closed-loop" system so the room air that is cooled stays in the room. This is much more efficient and will perform much better. I have a 12,000 BTU unit which does a very good job in my bedroom.

If this room has a suspended ceiling be sure to also remove any returns or supplies. How is the office heated/cooled? Does it have a suspended ceiling?

How are you dealing with the condensation from the A/C now?
 
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Old 04-17-21, 04:48 AM
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I don't think you are getting much radiated heating from the exhaust hose. The problem is that every bit of air you are blowing outside is replaced by unconditioned air coming into the room to replace what you pumped out. A two hose portable AC would work much better. You can also install a window AC exhausting into the house. Obviously you would need a tub or container to catch the condensate dripping out of the window unit and it would be heating the air in the rest of your house so your central AC will run a bit more often to cool the main house.
 
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Old 04-17-21, 08:15 AM
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Thank you to everyone for responding.
In an effort to see if I could narrow down what was causing or contributing to the lack of cooling, I decided to take one part of it out of the equation.

To respond to Tolyn Ironhand, The room has an A/C register from the building HVAC which I had blocked off by both closing its louvers and placing a magnetic sheet across it. The room has no returns. As for condensation, this hasn't been an issue yet. The portable unit claims to use the condensate in its internal processes and requires no action on my part.

What I did yesterday before leaving the building was to install a Zipwall with the portable A/C exhaust vent coming through the Zipwall (I wasn't concerned about that exhaust air for the purpose of this test but it was plumbed into an adjacent room with its door closed as much as the hose would allow) leaving just about 6 inches of the exhaust hose on the interior side of the Zipwall.

I closed the Zipwall as much as I could given the hose was now protruding through.

I left but kept a close eye on the equipment through remote means. Temps never went above 78, which is not the target of 70 but it is far better than the bread proofing temperature it was.

I see two possible explanations, A) The exhaust hose was contributing far more return heat than anticipated
and B) having the Zipwall open a bit allowed for air from the main building to enter and replace the air being diverted to the partially closed off second room

What do you think?
 
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Old 04-17-21, 09:05 AM
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having the Zipwall open a bit allowed for air from the main building to enter and replace the air being diverted to the partially closed off second room
I would suspect this is more the reason than heat from the exhaust hose. Before, with the door closed, the room was "starving" for air due to the negative pressure in the room with the door shut and all vents closed. The only place air could get in is likely under the door. With the larger gaps in the zip wall, the air could flow more freely.

As mentioned before, the zip wall is not ideal. You are now using the office air to cool the A/C unit, and if you are ejecting the A/C exhaust outside, you are now creating negative pressure in the office and that air will need to come from outside as unconditioned air.

If you really think the exhaust hose is giving off that much heat go pick up some flexible insulated HVAC ducting, remove the flex duct, and sleeve the insulation over the exhaust hose.
 
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Old 04-17-21, 09:24 AM
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Thanks for replying.
I'm headed out to get some insulating sleeve for the exhaust tubing. With a laser thermometer, it is 105 degrees Fahrenheit. That is toasty. I am going to look for ways to divert this heat to work space when winter comes. It can actually be of use to me then.

Until the dual hose unit arrives, what is the most efficient setup for this single hose unit? Would it be better to place it outside that room and vent the exhaust outside as I am now or vent it to the return for the main building A/C (though I can't help but think it would over-work that A/C) and have it discharge the cold air into the equipment room with a venting hole cut into the wall on a wall that would be best suited for this.

Or leaving it as is, in the room it is cooling and adding a vent to a wall to allow starved air to come in.

or

Leaving it in the room it is cooling and adding a vent to a wall to allow starved air to come in but also directing the exhaust towards the main building A/C return.


 
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Old 04-17-21, 01:23 PM
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I insulated the exhaust hose. Put a 10" x 5" vent in the wall to the hall so it can pull air in, then closed the door.
It is not cooling lower than 80 degrees.

Could it be that despite the 50CFM ceiling fan helping to pull air through the exhaust hose, the hot air has an issue with going up before going out? Or is it more likely the 3 bends the vent hose takes on its journey to the outside is the cause?. Literally all that changed from 70 degrees earlier and the 80 degrees now is the route the exhaust hose takes being vented.
 
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Old 04-17-21, 03:36 PM
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I know your original post said you didnít want anything permanent, but Iíd put a mini split in and be done with it. No point in reinventing the wheel when a mini would quickly cure the issue.
 
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Old 04-17-21, 04:32 PM
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Roughneck77, I am slowly arriving at that same conclusion myself. I'm looking at ductless systems as it would be the least invasive install. Is that what you are referring to when you mention mini split?

The upside, other than being a solution, is I can then expand on the equipment and the additional heat load won't likely cause problems down the line.

Bummer. But affirmation of what needs to be done is reassuring in and of itself.
 
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Old 04-17-21, 04:41 PM
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Yes, ductless is a minisplit. Very popular for IT rooms, equipment closets and other cooling sensitive equipment.
Just be careful on brands. The cheap no name brands online often offer little to no support, and are basically throw away style units where there isn’t really any parts available to fix it when it breaks.
 
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Old 04-17-21, 05:30 PM
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I'm looking at MrCool. Would this be a good one? My install is very straight forward. The line needed is about 18 feet. Straight shot towards the outside. Panel is right there for electrical.
 
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Old 04-17-21, 05:37 PM
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Seems to be a popular DIY brand. I’ve never worked on one myself.
Stay away from the precharged linesets and quick connect fittings. They leak.
 
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Old 04-17-21, 06:05 PM
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I've never used a Mr Cool either. All the HVAC folks I've worked with always recommended Mitsubishi or Fujitsu. Though maybe the money you'll save on a Mr Cool will be worth a potentially lackluster warranty support.

You may want to consider a low ambient kit. I know we had one installed for a server room HVAC to allow it to provide cold air even when it's cold outside without freezing. Not sure exactly what it is for a mini split system. Experts here?
 
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Old 04-17-21, 06:13 PM
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Most mini splits have the technology built in to operate in cold weather without issue.
Low ambient, and/or fan cycling controls are for conventional equipment that must operate in cold weather.
Conventional mechanical cooling equipment starts to have issues around 60-65į ambient and below.
 
Zorfdt voted this post useful.
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Old 04-17-21, 06:47 PM
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I will call some local HVAC contractors but I doubt they can beat or even come close to the price.
I do like that the MrCool is capable of cooling even at 5 Fahrenheit which is colder than it has been around here in a very long time. The lowest temperate we usually see is 18 Fahrenheit.

I also like the cost savings. Of course, that could come back to bite me in the ass.

The MrCool is precharged. The main unit has the refrigerant and you first connect the metal line from the air handler to the condenser and then release the valve to let the refrigerant out. At that point, the lines can't be removed without HVAC equipment and of course, refrigerant. The lines are not quick disconnect, as far as I can tell as they all appear threaded.
 
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Old 04-17-21, 07:18 PM
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No, that is incorrect. The outdoor unit will come precharged. This is common. Some linesets come charged with refrigerant and are connected via quick connect fittings. These tend to leak refrigerant.
Your probably looking at a normal lineset. It will have flair fittings. And will need pressure tested and evacuated with a vacuum pump. Simply connects the lines and opening the valves to release the refrigerant will destroy the unit.
Post a link for the unit your looking at.
 
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Old 04-17-21, 07:26 PM
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MrCool 24KBTU

I read it again, I think the lines are quick connect though in a youtube video, the guy seems to be threading them/
 
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Old 04-17-21, 07:32 PM
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That system has a 25’ precharged lineset. For which you have to use the whole 25’, and loop the unused line somewhere.
I wouldn’t suggest it. I’ve had 80-85% of precharged line connections I’ve dealt with leak. They are also very easy to cross thread.
 
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Old 04-17-21, 07:39 PM
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I can easily loop the line. That isn't a concern to me. Leaks would be. I'm very careful so I wouldn't think much of cross threading, especially now that you made me aware of it. Leaks would be something I've very little control over and that is worrisome.

What would you recommend? though, cost is a factor...
 
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Old 04-17-21, 07:44 PM
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The loop has to be done horizontally, not vertically. Not doing so creates an oil trap that will kill the compressor.
Id suggest a non-precharged line. Although you’ll have to spend some money on tools and equipment for the installation. Like nitrogen, a nitrogen regulator, flair block, vacuum pump, micron gauge, and have some technical ability.
 
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Old 04-17-21, 08:21 PM
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I am fairly confident I could do it but I don't have the tools and in PA, getting refrigerant isn't a walk in the park if you are not an HVAC tech. This is why the MrCool has appeal. I'll have to do some searching and focus solely on their negative reviews.
 
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Old 04-18-21, 04:55 AM
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While a mini-split system would be ideal your looking at $2000 for the Mr. Cool and about $5000 for a pro-installed unit. On top of that, you will have to make penetrations through the outside wall for the line set, drain tube, and electrical.

IMO a dual hose portable A/C will work fine for your application. You may still have to deal with the condensation, but with mine, I just drain it into a jug and swap it out as needed. You might have to build a stand for the unit to sit on for gravity to do its job.
 
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Old 04-18-21, 06:31 AM
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The loop has to be done horizontally, not vertically. Not doing so creates an oil trap that will kill the compressor.
Id suggest a non-precharged line. Although youíll have to spend some money on tools and equipment for the installation. Like nitrogen, a nitrogen regulator, flair block, vacuum pump, micron gauge, and have some technical ability.
I looked at the Amazon page and as much as I say I hate mini-splits as the Mitsubishi one in my rented apartment does not work right (likely an installer issue!)

The MRCOOL units look nice I like it even has a temperature display on the indoor unit unlike the Mitsubishi ones where the only place to see the set temperature is the remote.

I was also looking at the customer provided pictures and some coiled the extra lineset in a giant circle like I do with my stored extension cords, I don't think that is good?

While a mini-split system would be ideal your looking at $2000 for the Mr. Cool and about $5000 for a pro-installed unit. On top of that, you will have to make penetrations through the outside wall for the line set, drain tube, and electrical.

IMO a dual hose portable A/C will work fine for your application. You may still have to deal with the condensation, but with mine, I just drain it into a jug and swap it out as needed. You might have to build a stand for the unit to sit on for gravity to do its job.
I also dislike those portable ACs but never dealt with a dual hose unit before.

I got a single hose portable AC I would never buy a single hose unit and I did not buy this one anyway can I make this a dual hose unit? I'm good at mechanical stuff but I don't know what I have to do to achieve this.

I use an old cat littler container and I drilled a hole in the lid just big enough for the included drain hose I set the timer for 5 hours (I did not do that once and came back to a wet floor as the container overflowed!)
 
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Old 04-18-21, 09:10 AM
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There's the rub Tolyn, 5k to cool one room is not reasonable to me. I put in 2 new Trane A/C units at my house 2 years back and each one was 10k. Those were the second highest tier pieces of equipment I could put in and cool entire floors of the house. To cool one room for half that is insane.

This is why the MrCool has appeal. One room=2k is reasonable.
 
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Old 04-18-21, 10:42 AM
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I did not buy this one anyway can I make this a dual hose unit?
That would all depend on how the unit is constructed and if there is a way to separate the cooling air to the room from the air that passes through the condenser coil.

With my dual-hose unit, the room air is only circulated through the evaporator coil while the air that passes through the condenser coil is drawn from outside, passes through the coil, and then is exhausted back outside. It works very well.

The Mr. Cool unit looks interesting as a DIY solution as long as you have enough line set and can find somebody to service it if anything goes wrong.

I should also mention that if you are renting this space, you are likely not allowed to install any HVAC equipment or do any electrical work in the space. Even with the permission of the landlord.
 
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Old 04-18-21, 12:56 PM
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I am leasing the building but when I did, there were no interior walls. It was like a loft, all open space. I improved it by adding interior walls/rooms where I needed them. Why would I be precluded from adding this A/C? I've found nothing in the agreement that precludes this. The owner with whom I have the lease from knows I need this additional cooling. I planned to have an addendum drawn up once I settle on a given solution so it is added to the lease. I do this when ever I need to change anything to the building. He's never said no, only that it is done correctly and with appropriate permits.
 
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Old 04-18-21, 02:24 PM
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Wow!
I cant believe how many words there are in this thread!

A portable ac unit as long as the btu rating is similar could work as well as any other units suggested.

The cooling side of a portable unit is not meant to be ducted .
Anything you attach could and likely would greatly reduce its capacity.
They are also meant to re-circulate the air through the evaporator coil, not pass the air through the coil one time.

A suggestion is to place a portable 2 hose unit in the space you are trying to cool.
Then within reason what is meant to be ducted outside the room are the intake and exhaust hoses.
 
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Old 04-18-21, 02:38 PM
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I have a two hose unit on order and I will certainly test it before moving to the next step. It may simply be an issue of insufficient cooling capacity for the heat load and I may need more cooling than portable units are intended to deliver, without going commercial. I looked at a few of those and they approach the cost of a split system so at that point, I'd just get a split system and be done with it.
 
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Old 04-18-21, 04:50 PM
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That would all depend on how the unit is constructed and if there is a way to separate the cooling air to the room from the air that passes through the condenser coil.

With my dual-hose unit, the room air is only circulated through the evaporator coil while the air that passes through the condenser coil is drawn from outside, passes through the coil, and then is exhausted back outside. It works very well.

The Mr. Cool unit looks interesting as a DIY solution as long as you have enough line set and can find somebody to service it if anything goes wrong.

I should also mention that if you are renting this space, you are likely not allowed to install any HVAC equipment or do any electrical work in the space. Even with the permission of the landlord.
I never had it apart except to clean the filters (it has 2) it looks like it draws room air in the back where one filter is (it is near the single hose and I touched the coil so that is definitely the condenser! OUCH!) the other filter is near the evaporator and the water hose.

I do know when I used it and I had the mini-split on (it was a somewhat warmer day and it seems to work better when warmer) it actually seem to make it work harder!

Anyway this is what I was given

If you lease do you intend to take the MRCOOL with you if you leave?
Also since this sounds like a commercial (from what you describe or is it a house?) I would tend to lean toward something better like a Mitsubishi or Fujitsu but all warranties are void if you DIY it. From what I see the MRCOOL is catered toward the DIY market.
 
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Old 04-18-21, 05:34 PM
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I would take the split system only if made to do so. I'd leave it, if given the choice.
It is a commercial property but I'm not required to install commer4cial equipment.
As it turns out, these MrCool units are marketed as suitable for server rooms and while
this is not a server room, such marketing means that use outside of residential cannot be
frowned upon by the manufacturer. The MrCool warranty is not voided by a DIY, it is after all
marketed as a DIY. Per MrCool:*State certified or licensed HVAC contractor not required for warranty on
the DIY series units. (Always check your local laws.)
 
 

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