Dimi will remain at Cardiff for the rest of the season after failing in the appeal to return to the Liberty.
The keeper will provide coverage for the injured Peter Enckleman although he is expected to remain as backup to Heaton rather than go straight into the side.
Dimi had spent much of the last three months on loan at Swansea but a last minute attempt to extend that loan was dashed when the keeper got stuck in traffic last Monday.
His last appearance in a Swans shirt was in the FA Cup win at Portsmouth where he picked up a man of the match award for his clean sheet