Heimer IS VIABLE IN RANKED!
Just gonna let everyone know that no matter what people say, The Big Donger is extremely viable in ranked, in both teams and solo queue.
I will go on to provide three reasons/examples why.

1.) Turret damage is frikken overpowered. They have 1.75 attack speed and damage that really hurts. Combining a E W Q combo can take out half of an opponent's health.
2.) The ult is sweet. What other champion has a choice of THREE ULTIMATES that they can use? He can use his ult to get out just about any situation, and in ganks he nearly always gets a double.
3.) Heisendong. A challenger player who ONLY plays heimerdinger. Look up his LolKing. Also, if you go to champion.gg you'll see that heimer's toplane winrate in Plat+ is higher than that of any other champion.
Finally, to prove he's good across all elo, look me up too. http://www.lolking.net/summoner/na/50773610 I climbed from bronze 3 to silver 3 using heimer (plus a teensy tiny bit of Yi, but we don't speak of those dark days).
However, this last message I give to all players who want to dong their way up in ranked is quite controversial:
HEIMERDINGER IS NOT A NO-SKILL CHAMPION.
There is DEFINITELY a complex strategy to the donger that honestly takes a loooong time to master.
Most Bronze V noobs will just tell you "Heimer=noskill nub, just place turrets and win." That's why they're in bronze V. Ask Heisendong in his twitch.tv stream whether heimer requires skill. 
Adios amigos, and may great donging lie in your future.
has 3 ultimates ;-;
Are those turrets? Cute.
and
).
Also learn your positioning,it will help ALOT.And don't forget to practice with EVERY single part of your kit(yes, even your R+E version of your ult).
Good luck and always RAISE YOUR DONGERS!!!