:D We've been having trouble keeping shower water hot long enough to take a shower. Was told tankless coil for domestic hot water was clogged and would need replacing. Was cosidering replacing coil or abandonning it and installing a SuperStor SSU-45 indirect water heater in it's place and running off zone for basement. Thankfully I came to "Ask Me Help Desk" before committing to either. After reading numerous posts with similar problems, I took your advice and flushed the boiler. WHAT A DIFFERENCE!! We no longer have to turn up the heat to keep water hot long enough for showers. Thanks Tom.
Only question I have is this: Should I leave furnace turned on while flushing or turn off to keep from constantly cycling due to cold well water?
Thanks again Tom. Your advice was right on the money here. Hope others follow your advice and achieve same results. I also found that my boiler drain valve now leaks and had to cap. Will replace with new 1/4 turn drian valve this weekend.:D

Hey Paul, Glad we could help. Sometimes the simplest thing will make a difference.

Should I leave furnace turned on while flushing or turn off to keep from constantly cycling due to cold well water? Since flushing the heater only takes a minute and is accomplished by forcing cold water down the dip tube to the bottom to stir up the minerals built up down there and flush them out the boiler drain I would leave the furnace on. It's not going to make much difference either way. Regards, Tom

The T-537 and T-540 are my favorite here:

Ball Valves - Legend Products (http://www.superiorspecialty.com/Main/Plumbing/Legend/BallValves.htm)