By EC you do mean Established Church? the Church of Ireland was the State church so many of the records were sent to Dublin for safekeeping. Not sure if there is any list of the destroyed records but you can often tell from the date church records start that this might be what happened to them.
"Historically, each parish in Ireland kept its own records. Because the Church of Ireland was the state or established church, these parish records were considered state records. In 1876 a law was passed requiring that Church of Ireland parish registers be sent to the Public Record Office (now the National Archives) in Dublin for safekeeping. This law was amended in 1878 to allow parishes with good storage facilities to retain their records, so not all parish records were sent to Dublin. Further, some ministers made copies of their records before sending the originals to Dublin. Thus, many Church of Ireland records remain, even though the records sent to Dublin were destroyed in 1922 when the Public Record Office burned."
http://familysearch.org/learn/wiki/en/Church_of_Ireland_RecordsSchool records are another matter entirely and yes, they still do turn up in the strangest places- lofts and cupboards in houses, museums, etc. PRONI in Belfast has gathered a large number of them covering Northern Ireland counties.
