Ink dries. Small air/ink channels can clog when ink dries. Printer dots (and therefore nozzles) are really small. That's pretty much the reasoning behind having to constantly use an inkjet printer to avoid having the heads clog. You need to keep the ink flowing.
You can have someone visit your printer and run a print every week or so. It could be that it doesn't need to be quite that frequent. My Canon Pro-100, a dye-based inkjet printer, seems to be ok, so long as I remember to print/clean at least once a month, but is probably happier with weekly printing. But that's just from my personal feelings from having soaked, rinsed, and scrubbed a ton of dried ink out of clogged vintage fountain pens while restoring them.
If the same logic for fountain pens holds for inkjet cartridges and printheads, I'd say that you either make sure someone regularly prints with the printer, or you consider completely flushing/cleaning out the printheads with some kind of cleaning solution, and depending on the type of head,
store it dry*, or store it wet (i.e., with cleaning solution in cartridges) to keep the heads from drying out. There are various reports on the efficacy of storing the head in an airtight container with a moisture source (think humidor), but it can depend on how the individual printer is designed. See this post on a pcreview.co.uk mesageboard thread, which mentions the three basic types of printer designs and the strategies for the three different kinds (permanent head, semi permanent head, and integrated head and cartridge). The strategy about is for permanent head printers.
The whole point, though, is to keep ink from drying in the tiny channels.
Obviously, the relative humidity, length of time, and how the printer is stored is going to affect how much the heads dry out. You'll probably want to make sure it's in a cool dry place, and possibly wrapped in plastic.
Worse comes to worst, you could consider simply purchasing a replacement print head off eBay, although in some cases (like my Pro-100), it may be cheaper to just get a new printer.
I'd recommend poking about the printerknowledge.com messageboard, and seeing what they've got to say about storing Epson printers, and what methods may or may not work for your situation. I googled up these threads on that site:
*Going through those threads, apparently even Canon ships a brand new head to you with some lubricating agent in the head in a hermetically sealed pouch--dry is NOT GOOD.