Advise to do a minisplit with low ambient wind baffles. You will be able to have cooling in the temperature range you need. Look at Daikin. They are headquartered in Dallas.

If you install two of the "right" mini split indoor units, one in your equipment room and another elsewhere, you can transfer heat from the equipment room to the rest or your house rather than to the outdoors. The typical residential models will not do that. Others may have equipment that does that, but I know that Mitsubishi (City-multi system) and Daikin do. In addition, they can make residential hot water or heat your pool. I would be surprised if you can't put a coil into your hair handler rather than your second (third, fourth,...) mini split indoor unit.

This kind of equipment will cost a lot more, however, and your typical residential contractor will probably not be trained to install or maintain it. You have to consider whether the money spent will be worth what you save in energy conserved. I don't know which ones come in single-phase either.

I used to represent Fujitsu in New England and did a lot of these systems with mini-split systems. These were generally commercial systems and what you are describing is a commercial system. You will generally get cold temps, but it warms up in the daytime. You can do this with a minisplit. I did one system that had a carload of equipment and for that one the solution was to put the condensing unit on a rack interior to the warehouse. For emergency operation on other systems we used a Tjernlund Enforcer combustion Air inlet fan tied to appropriate filtration and temperature control. This was emergency only and for short periods as you have to be concerned about humidity and static introduction into the space. The proper equipment for this is a Leibert system. Once you get the price on it you will like the mshp

Thanks for the feedback. It looks like we are going to go with a Mitsubishi system for the equipment room and a conventional system for the rest of the house.

When I was revamping the HVAC in my house about two years ago, I noticed
that with Mitsubishi, the 1:1 systems had better capabilities than the
multi systems. They 1:1 had the I-see sensor and associated directional
control, better low temp capability (H2I) and higher efficiency. The last
I attribute to better match between indoor and outdoor parts with
attendant increased ability to throttle down to lower rates with outdoor
unit. I think that since then some of the features have been added to the
multi split line.

I'd be tempted to put a sleeve unit through the wall if the room has an exterior wall and noise was not an issue. Some of them are excellent at humidity control if the fan can be set to cycle with the compressor. It would be a lot less expensive.