Warlord is, basically, not a good healer, maybe only Runesmith is the worse healer amongst leader classes. But Warlords have their own edges. No other leaders are better at granting extra attacks and moves to one's allies.
Inspiring Warlords have the second total highest healing in-game, behind Clerics. At Paragon with Fight On any Warlord is the only class that ends up with 4 healing words/encounter, and like all the well supported healers at Epic each one target two targets (which is 8 surges/encounter before any other methods of healing).
Realistically most Leaders have roughly the same healing till Paragon (2 words/encounter, a utility here or there, and a daily that usually has some method of healing the whole party). If you don't take
any of the utilities/dailies/encounters that also heal you might run into issues on a really hard fight.
Roughly the order is, in terms of healing/damage prevention (Chord of Resilience etc.,)
Pacifist Cleric
Non-Pacifist Cleric
Inspiring Warlord
Artificer
CHA based Warlord
Sun Warpriest
Non-CHA based Warlord
Sentinel
Bear Shaman
Bard (barring Tiefling/Flaming Weapon/Stirring Song)
Ardent
Runepriest
If it isn't listed it is because I haven't run numbers on it. The reason everyone loves Warlords is the rank so high on the healing and they add a ton of enabling (extra attacks on the striker and etc).
If you're running low on healing as a mid-Heroic Warlord consider Rousing Words (level 6 utility) and Stand the Fallen (level 5 daily attack power). You can retrain either later when you find you don't need it (which should be around level 11).
Ardent and Runepriest get worse as you level, because they have so little support. At Epic they won't be able to grab the 2 targets per Word feat, for instance (because it doesn't exist /cough) putting them at 1/2 the healing any other Leader should have.
To answer the OP's question, Artificers are great. You can move surges around for free (every other healer needs the ritual Comrade's Succor), you get 2 extra surges/day for the party, you can use Magic Weapon as your Standard every single round while taking Immediates as your Encounter powers, and there are other fiddly benefits. They aren't the powerhouse that Clerics are in terms of healing, but they are very good.