What are all those big , heavy white chips, that are pouring out of the Water Heater drain outlet ? How many times do I have to drain and refill those tanks, to flush all those white flakes out of the tanks ?

mineral deposit. Until they stop coming out.

Lime deposits.

Is it true that mineral deposits are more likely in electric water heaters , and not so much in Natural Gas Water Heaters ?

You don't necessarily need to drain and refill. Leave the cold water valve on top open and then open the drain on the bottom, and just let it run until it runs clear. Do it about once a year.

Canvas back 2 it doesn't make a bit of difference in all honesty. The ok only one that will never get them is the one that's never used . Sorry I don't mean to be a wise guy when I say that.

Do it until you get a water softener and that won't stop it, just slow it down.

I thought there was a chemical that can be used to flush the water heater.

Does your city use Chloramines as a disinfect? If they do the chloramines change when heated. We have big troubles with this plugging up fixtures and water heaters. Circulating vinegar thru the heater helps break it up if you have a tankless heater. One of the scarier effects of this is how it plugs up the relief valves and eats holes in the piping and valves.

if you can drain your water heater drain it .dont shut off the water but turn off the power or turn it to pilot if gas ,yes most gas water heaters will not have the deposits that electric tank water heaters do .also depends on your water ,are you on a well ?how hard is your water .do you have a softner on your water system ?it will never hurt to remove the sediment from your tank but i would not completely drain your tank .but if you do make sure you get all the air out of the tank before powering it back on ,gas water heater you don't need to worry so much as they heat from the bottom .maintain your water heater and hopefully it will last a long time because they are not built to last you in our disposable system !

my hot water heater is power event gas , I turn off the switch so it doesn't run , there is a hose I leave connected to the valve and 1-2 times a year turn off switch open valved let it flush into my sump pit and be pumped out

I've cleaned water heater by draining the heater then pouring a gallon of white vinegar in through one of the dielectrics. Let it sit a while and then flush it again. I also pull the drain valve on the bottom of the water heater and install a full port ball valve and nipple for future flushing. Sometimes I'll tape a piece of copper pipe onto a shop vac hose and stick it through the drain valve hole before I install the full port valve. The copper pipe facilitates breaking up the lime and calcium calcium deposits. I've done the same with a shop vac going through a electric element hole when replacing a element on a electric water heater.