another quick question for you guys. im not sure how much amperage the house gets from outside. is it ok to turn off a 20amp(kitchen outlet for window a/c) and a 10amp(dishwasher doesnt work), that are unused in order to hook up the 30amp for the heater.
Well 1st I would look at the "Main" breaker at the top of your panel, that should tell you the amp size of the service.
Let me back up a second, this is a "Main" breaker you are coming out of, correct, IOW you *DO NOT* have a sub panel correct?
As far as "turning off" those other 2 breakers, Do you mean you want to remove those 2 breakers, and put your 30 amp 220 v breaker in there place,
or do you have room in the main without removing the A/C and D/W breakers?
Either way really, you don't have to worry. The 20 Amp A/C breaker and the 10 Amp D/W outlet's will not be pulling any amps if the appliance's are not running.
As Far as a Sub panel, only reason I ask is if it is a *Sub Panel*, you want to make sure you hook the bare ground to the *GROUND* buss in the sub, and not to the Neutral buss.
The Ground and Neutral should be electrically separated from each other in a Sub Panel,with all white (neutral) wires running to the isolated neutral buss, and all grounds, (bare) running to the Ground Buss.
The Neutral buss should *NOT* be bonded to the Sub Panel case.
Hope this makes sense.
Thanks, Tony