This question is for Speedball1 or anyone else that may know. The gas water heater that I have is approximately (11) years old. I have heard pros and cons about flushing it out at this point in time since it has not been done before; I inherited it, so to speak. I have been told that doing so is similar to flushing out an old radiator in a car, i.e that you could possibly do more damage than good by breaking loose some old rust and junk and clogging everything up. Yeah, I know it's almost time to replace but until it quits I will probably keep on keeping on! Can an old broad like myself do what you are talking about? I'm not really THAT old, just mechanically deprived!

Water heaters aren't like radiator, and that is an old wife's tale anyway. Flush it now. Connect a garden hose to the drain spigot and direct the hose outside or into a floor drain. Open the valve for this spigot, do not touch the brass emergency valve up near the top and do not close the water supply to the heater. Let it run to the hose for about 2 minutes, all good. Did you also have a question about tankless units, it was in your title.

Agree completely with the above.

Only thing to be prepared for will be to have a BRASS (or can be plastic) BOILER DRAIN CAP, just in case the drain at the bottom of the heater doesn't want to close after flushing the heater. Here, at times, the sediment getting flushed out can hang up at the drain and can cause difficulties in closing things down. If you have the drain cap ready you won't have to "panic" when/if it happens, OK?

Another thing here would be to make sure that after flushing the heater you run the hot water for the first time through a faucet without an aerator in place... sediment disturbed can clog the aerator so it is best to remove the aerator prior to purging/clearing the lines, OK?

More questions just let us know, OK?

Mark