Hi mediocrejoker,
A salesman told me the other day that some boxsprings will not provide the correct support for a pocket coil mattress. Is there any truth [quote]to this? How can I determine whether a boxspring will be appropriate)[/quote]
This would depend to some degree on the specifics of the mattress and it’s overall design but in general a pocket coil mattress will do best on a firm foundation (slats or wire grid type) that provides firm, even, and either “no flex” or “limited flex” support and doesn’t require a traditional “box spring” (that has active springs). Innerspring mattresses that use helical wires will usually do best on an active box spring which provides some shock absorption for the mattress. You can read more about the types of foundations or box springs that are most often used with different types of mattresses in post #2 here.
The “ultimate” authority though for the best type of foundation or box spring for a specific mattress would be the manufacturer of the mattress but in general terms a pocket coil will be fine on a firm non flexing foundation (like the floor)
Phoenix