The whole US is currently experiencing a massive heat wave, but we seem to be getting more than our fair share of it down here in Texas. The heat in our shop’s been almost unbearable as the outdoor temps have rised to over 100 degrees F every day this week. (We even hit 106 one day.) We went in search of a way to take the hurt out of the heat and ended up trying out one of AdobeAir’s Mobile MasterCool series portable evaporative coolers.
All coolers work by transferring the energy from the hot air to somewhere else or converting it to some other less-annoying form. In normal household A/C units, a coolant such as Freon is used in a closed system, sapping the energy from hot inlet air to evaporate the coolant, then releasing the heat outdoors as the coolant re-condenses.
Evaporative coolers — or “swamp” coolers as you may have heard them called — work on the basic principle of cooling by the evaporation of water. Evaporative coolers are very simple machines. They consist of a fan which draws hot inlet air through an “evaporative pad” — a piece of porous material which is constantly soaked with water via a pump and reservoir. Energy is removed from the hot air as it evaporates the water.
As with all coolers, the heat must go somewhere. Unlike closed-system Freon-based units where the heat is “moved” to another location, evaporative coolers simply blow out the resulting water vapor along with the cooled air.
This leads to the basic limitation of evaporative coolers: the source (inlet) air must be dry enough (low enough in humidity) to allow for evaporation. If the water in the evaporative pad can’t evaporate, no cooling occurs.
This means that the more humid the air is around the cooler, the less cooling it’ll provide. If you live in a very humid area such as Florida or Houston, you’re going to see far less performance from an evaporative cooler than you will if you were to live in, say, Arizona. It also means that you can’t use an evaporative cooler in a sealed-off environment. As the cooler operates, it’ll continue to add humidity to the air until the air is too humid to allow evaporation — at which point it’ll cease to cool.
With this in mind, read on to take a look at the MasterCool MMB12 — one of AdobeAir’s mobile “spot” coolers.
We picked up our MMB12 from a big-box home improvement store. It came mostly assembled in a large box. (The unit itself measures 26-1/2″ W x 26″ D x 40″ H.) The wheels were already attached and the filler float system was already installed as was the drain plug in the bottom of the unit. The only piece remaining for us to install was the plastic drink-holder tray that mounts to the top of the unit.
The MMB12 is designed with the bottom of the unit as a 7.5-gallon water reservoir. It has a garden-hose fitting near the bottom rear of its base which attaches to an internal float-style regulator that opens when necessary to automatically replenish the reservoir. The manual indicates that any water pressure up to 100 PSI is OK, and this shouldn’t be a problem for most homes and businesses (which are usually regulated to 75 or 80 PSI).
A pump assembly stands in the bottom of the reservoir and pumps up a clear tube to a black plastic T-fitting at the top of the unit, which directs water to the left and right sides. Removable metal frames on each side hold AdobeAir’s “premium evaporative pads,” which look like paper or cardboard radiators. They’re about an inch-and-a-half thick and soak up water quite effectively. The top of the frames feature an angled metal flange which catches the water from the T-fitting and directs it down a channel at the top of the frame. Holes in this channel allow it to act as a manifold to direct water across the entire evaporative pad.
In the center of the unit is a caged 5.6A fan which draws air from inside the unit (through the evaporative pads) and exhausts it out the front through a protective grille. Outside the grille are a series of vertical and horizontal vanes which can be used to direct and channel the cooled air.
A sealed switchbox on the back of the MMB12 holds switches for the pump and the two-speed fan.
As you can imagine, we were pretty excited to fire up the MMB12 and experience a cooler shop. We ran into a few problems out of the box, however.
During shipping (or shelving — who knows?) some damage occurred to our unit. The plastic T-fitting had broken off at the inlet fitting. We returned the fitting itself to the store we bought it, and after some wailing and gnashing of teeth — they wanted us to return the whole unit as opposed to just the broken piece — they allowed us to swap the piece with a working one from another unit. We drove back to the shop and installed the unbroken component.
Following the instructions, we attached and pressurized the filler with a garden hose. We did run into a bit of trouble with the attachment as it wanted to rotate as we screwed the garden hose into the fitting. This is a problem because the float is directly attached and won’t operate if not set at a flat angle. This was made a bit more difficult by the fact that the float mechanism isn’t extremely durable and is hard to hold in place during the hose connection without damage. With much careful work, we managed to get the hose attached, at which point the float worked perfectly and filled the reservoir. We did adjust the float slightly as at factory setting to would have slightly overfilled the reservoir.
We then turned on the pump for a few minutes to allow it to pre-soak the evaporative pads before we engaged the fan. Upon turning on the fan, we did indeed feel some cooler air coming out of the unit. An HVAC thermometer indicated that it was 98 degrees in the shop, and the air coming out of the unit ranged from 88 to 85 degrees. This was a bit shy of our expectations set by AdobeAir’s documentation and advertising which indicated that we could expect “sub-80-degree air in most climates” and “up to 30 degrees of cooling.”
So, we started troubleshooting. Concerned that we might be over-humidifying the air, we opened another roll-up door to allow in additional dry air. This resulted in little or no change to the output temp. Secondly, we noticed that one of the evaporative pads wasn’t staying completely wet. We checked the unit with a level and discovered that that wasn’t the problem. (You want to keep the unit on level ground as the manifolds that wet the evaporative pads are gravity-fed.) So, we turned off the pump, ran the fan a bit to dry out the pads, and removed them. Looking closely at the manifold in the top of the offending pad’s frame, we discovered that the holes near the “dry” end were closed up more than the ones on the “wet” end. We used a screwdriver to carefully pry open the closed up holes to try and more closely match the ones on the other end.
We then re-assembled the unit and fired it up by the manual’s proceedures. This time both pads appeared to be uniformly wet, and indeed we saw slightly lower output air temperatures — as low as 82 degrees. During this time we approached sundown, however, and the temperature in the shop had dropped to 95 degrees, so it’s hard to tell whether or not the unit was responsible for the drop. Sadly, we have yet to be able to duplicate the company’s claims of sub-80-degree output. (Note: During the days we were testing, weather.com reported less than 35% humidity at our location.)
Of course, let’s be clear that we’re not complaining too much about 82-85 degree air. This feels downright frigid when you’re standing in a 98 degree shop, and does make a difference. The manual suggests using the low fan speed setting for maximum cooling, which is what we did. On the high setting output temperatures barely dropped below 90 degrees.
By placing the MMB12 near the specific area of the shop in which we were working, we were able to make the “spot” a bit more bearable. The vanes on the front of the unit are very helpful, and we adjusted them quite a bit to keep the air directed to our workspace.
You do have to be careful when moving the MMB12 because the level of water in the reservoir reaches very close to the vent holes, meaning that if you move it too quickly water’ll slosh out the sides. You also must keep the MMB12 level during the whole moving procedure. If you want to roll it up an inclide or lift it over a bump you have to shut off the fill hose and drain the reservoir first.
Our experiences with the MasterCool MMB12 didn’t match those portrayed in the marketing literature, but we still seem to find it a useful addition to the shop. Even a 10-15 degree cooling in the spot we’re working in makes a difference in the Texas heat, and we’re glad to have it.
We’re very skeptical of AdobeAir’s claim that the MMB12 will cool a 1000 sq. ft. area. Even taking into account the fact that the area in which we placed the unit has a 10′ ceiling (as opposed to the 8′ accounted for in the company’s numbers), we never saw the unit make a significant dent in the overall temperature in our 680 sq. ft. room.
It’s important to note that this isn’t a carefree unit to operate. You need to be prepared to set it up about 15 minutes before you want it running, and you’ll need to plan in 15 minutes or so to shut it down — more if you’re not going to use it the next day and plan on draining the reservoir. You’ll also need to make sure you have a water source (or a long hose) and power available where you want to use it and a level place to set it.
It’s also not cheap. Our unit sold for $397.00, and by the time you add a hose, a few plumbing fittings, and tax to that it ends up falling on the high-side of the $450 range.
That said, we definitely fall within those requirements, and we’re more than willing to pay the dough to stay cool. Though we were a bit disappointed with the unit’s performance, we chose to keep it rather than return it; We just need the cooling that bad.
As we own the unit, we’ll report back later on our longer-term experiences, including regular maintenance and any issues we might have. We did contact AdobeAir, and they indicated that we might be able to get more performance from the unit. They intend to have an engineer contact us, but we haven’t heard back from them yet. If we learn more during those conversations, we’ll pass the information on to you.
Other Units from AdobeAir
AdobeAir offers two other units in the MasterCool line, one larger than the MMB12 and one smaller. They also offer a wide variety of non-portable units, all of which are listed along with performance numbers on their website.