The 21-year-old has swapped Italy for Vicarage Road until the end of the season having found first-team opportunities limited in Serie A so far this campaign.
Despite the links between Watford and Udinese, as both clubs are owned by the Pozzo family, Merkel insists he was not talked into making the switch and that playing in England is a dream of his.
"The Udinese president spoke with me at the start of December and wondered if I could imagine myself going to Watford," he told the Watford Observer.
"I said to him I wanted to go because it was another country and I wanted to try something new and then two weeks ago I made the decision.
"I had lived in Italy for close to six years and it was good for me but I wanted to move - it was 100 per cent my decision to go to Watford."
Merkel has spent the whole of his senior career in Italy, previously representing AC Milan and Genoa, but he says that English football has always been an attractive prospect.
"It's always been my ambition to play in England," he said.
"For every footballer it's a dream - all modern footballers want to play here so I'm really happy to be here.
"I watched a lot of English football growing up. It's everywhere - in Germany everyone is watching the Premier League - so to play in England is a big dream for me.
"I always watched the big teams of course but now my favourite team is Watford, maybe it wasn't before, usually I'm a guy who loves the club he is playing for so now I love Watford FC.
"I am working hard to get match fit as soon as possible so I can show the Watford fans what I can do."