Hot water heater

Trying out the hot water today for the first time on 2017 Warwick xl. With and without  hook up  could not get hot water on ECO settings, is that normal. Hot water ok on HOT setting with or without hook up, although on hook up it appeared to only use the electric despite having it on the mixed setting.  Anyone got any useful info. Its a Truma Combi 6 E. The outside of the boiler was getting very hot on either power source, to hot to hold your hand on. Is that normal. There was a burning smell but suspect that's because its new.

Re the burning smell.

I have a Duo with the 4E version of yours. Others on this forum have discovered that only 3 of the 4 hot air outlets are populated, (BY AS, and quite contrary to Trumas installation instructions)
Mine had exactly that!
I did as others showed me on the forum, and installed a 4th outlet, total cost £30 or so, 10 min job (if you have the correct holesaw)
Not saying that's what the burning smell was, but willing to take a small bet!

The explanation for the burning smell is complicated, and I'm not sure I can remember it accurately enough to pass on. Something to do with the angle of the short exhaust pipe.
 (Sounded like a plausible excuse to me, but perhaps I'm too cynical? )
It's a well known problem which is suffered by a lot of owners, more prevalent when used on gas than electricity I think. Messrs Truma insist that it's nothing to worry about, so I guess we have to trust them.