ductshvac
For a room in the basement we connected a ceiling register to an existing duct. It is not very strong, but I found this product that might make it a little more powerful:
Does anybody know how something like this powered? Is it possible to connect it to the thermostat so that it only turns on when the heat/ac is on?
They do make thermostat controlled vent covers, this particular one is ~$60.
I'm not sure how difficult it is to install one of these (as I've never done it myself), but it sounds like this is exactly the type of thing you are looking for.
This is not a recommendation for this product, simply an example to show that they do exist.
It is difficult to properly cool two spaces with vastly different heat loads and only one thermostat.
Assuming typical computers and monitors and two users, you probably have about a kilowatt of heating or 3400 BTUs per hour.
Rather than run ducts, have you considered a dedicated cooling unit for your office? You can go with a small window unit. Even the smallest one is 5000 BTU and only uses about 500 watts when running. That's just a few pennies per hour and even that is offset by the reduction in load on the main unit. With the thermostat in the same room, its load response will be much better and the temperature extremes you have been suffering with will be eliminated. Plus you can turn it off when no one is there and save energy that way.
Lately my thinking is that ducts are basically parasites and efficiency goes up when the heater/cooler is in the same room as the load. In the past, the equipment cost was lower with a shared unit but operating costs (energy) have gone up a lot (and will continue to go up) and that could change the equation on selecting shared or dedicated equipment. Comfort will always be superior with dedicated equipment.
Best Answer
The manufacturer's website lists several possibilities; from their FAQ for that range of fans: