One suggestion for the code is to replace or augment the read11 and read22 routines by one unique read routine that would detect which one it is and return 11 or 22 in chk
Don't mix error state with configuration information. That said, one could make a function int determine() that does just that. Typically it is called just once and remembered - you just needs one byte to keep the 11/22 flag of 8 sensors.
I'm not sure it is so easy, but for example, having both [2] and [4] zero with a DHT22 should almost never happen, right ?
possible but one could only account readings for which [2] and [4] are zero AND the checksum is OK.
Assuming a valid reading, both numbers have one decimal place 0..9 =>10 possible values. This implies that the chance would be about one in hundred for an individual reading to have two 0's as decimal. That is a small chance but too big imho to make a reliable determine() function, it is definitely not deterministic. Multiple readings with will improve this number but as the device needs 2 seconds between readings so determine() function becomes quite time consuming.
Note that especially for the DHT11 one can use a (running) average to get a higher precision - and thus decimal places ).