Am trying to do my first flush since the tank auto shutoff last night. I reset the motherboard and it is working again but there is A LOT of sediment inside that I want to flush out before heating the tank back up. I saw a video where the plumber recommended replacing the flush valve with a full port valve to allow the larger particles to escape.


  1. is it possible my factory installed plastic valve is already the size, diameter, or same whatever measurement of the full port valve, rendering an exchange pointless?

  2. i heard these are easy to break. i do see where the threads are and want to remove the valve but obviously would rather have a tank with a small valve and some sediment rather than having to get a new tank if the piece breaks off. what's the likelihood of this?

would appreciate a reply asap! i'm going to pick up the full port valve now and will check back later.


...so no one responded and I removed the plastic valve anyway successfully. unfortunately the ball valve i got from the store doesn't fit the heater!...

How important is it to remove most of the sediment vs. some?

Installed the brass full port valve (needed nipples on both sides) and only the sides connected to the valve are both leaking. Did i not use enough tape (1 wrap) or need some thread sealant? Are they supposed to seal easily? Seems like people complain about leaks on these often.

  • What is the maker of your water heater? Dec 9, 2016 at 12:43
  • whirlpool--------
    – Jon
    Dec 10, 2016 at 10:25

2 Answers 2


How durable are the plastic boiler drain valves that are being used now? Maybe 20 years ago the plastic drain valve in the natural gas fired 40-gal tank in the house across the street cracked and was blown out . . . late at night. The old gate valve only partially stemmed the flow. I saw all the commotion and went across the street and opened the water meter cover so the main cutoff could be closed.

When I was getting a new 40-gal tank installed in a rent house I owned the plummer offered to change the plastic drain valve for a brass one he had on the truck. He put it in, but it leaked so he reinserted the plastic one. The plastic drain valve never failed in the 12 years the tank was in service. At that time I had a tankless water heater installed.

  • wow. i was just going to give an update and ask how to stop the brass full port valve that now appears to me leaking. not sure if i didn't use enough tape or was supposed to use some sealant. or was manufactured poorly. seems I tightened enough but i don't want to play around with it while the water is still flowing (hard for us to turn off water supply)
    – Jon
    Dec 10, 2016 at 10:24
  • Pipe dope paste will probably seal better than Teflon tape. Dec 10, 2016 at 13:40

Regular or once a year cleaning is a good way to extend the life of a water heater. Most of the sediment will flush out with the valve installed by the MFG. The large chunks are usually pieces of the Anode that has started falling apart. Checking the Anode is another thing that should be checked every few years and replaced when it starts to show heavy metal loss this will keep the big chunks out of the tank that are difficult to flush out of the system even with a larger valve.


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