I dont know exactly how much mastery i have but my shields are around 26.2k absorb. Im just wondering if my shield dissappearing so quick is ok? Like in twilight dungeons there are mobs that hit rather hard.
When i put my shield up its gone in 2 seconds...
What do i do ? Penance heal is mediocre to incoming damage. I have heard using heal is mana ineffecient as disc so if i use gheal im just burning through my mana. Do i just spam flashheal to get rid of that debuff to shield again ?
We need some context on you. Are you doing 5 man dungeons? What you're describing is about how I felt healing random tanks through troll heroics in about a 350 set. If you're new at priesting and that's why you're feeling mana crunched, just keep trying, and build up your gear level a little bit. Eventually you should be able to spam gheal a looooooooong time and never feel mana starved.
There's a lot of rhythm to playing disc, and if you get the rhythm wrong you'll feel ineffective.
Penance is better than you give it credit for.
Oh, and answering your main question, PW:S is a pittance of a heal. It's all about the whole cast chain with BT. Ideally you want PW:S -> Penance -> GHeal, that's your highest throughput single target cast chain.
you never spam fheal. never ever ever.
(there are players who can spam flash heal, but from your question i dare to think youre not one of them yet)
what do you heal, 5mans heroic, twilight dungeons you say? if 3 or more people take damage use power of healing, make sure you use prayer of mending on tank, keep shield on tank, use penance and gheal to heal damage. when you and someone took damage, you can use binding heal to heal it up.
heal is fine if your group doesnt take too much damage or between your group takes damage. when nothing is happening you can use heal on tank to remove shield debuff.
if you find twilight instances too hard to heal, maybe you should gear up a bit in earlier places/get more jp gear?
thats about all i can tell you without seeing your armory
I'm guessing that the OP is in leveling gear and has just hit level 81 dungeons (like Blackrock Caverns). Healing those is considerably more difficult than the previous WoLK dungeons when you hit them not in WoLK raiding gear.
I'm sure to be corrected if wrong - but here's my basic knowledge from healing disc in WoLK plus some basics on mana efficiency from healing on my shaman (ie, slow small heal is better if you can get away with it than bigger or faster heals):
You should use "Heal" as your main heal. It's slowish, small, but your most mana-efficient heal.
Greater heal is also slowish but it's large; it heals a lot, but it costs a lot of mana.
Flash heal if penance is on c/d and you need more heals nao!
The basic concept is, shield the tank, penance if you need to refill someone quickly, flash if they're about to die, PoH if the whole group needs some heals... divine hymn for a more powerful group heal.... but your mainstay will be the basic heal. Just be feeding the tank little heals constantly (but don't overheal) using basic heal unless something else happens.