[rw4smithers]

I want to install a 1 1/4" flushometer to my existing residential 1/2" line. I read that adding an expansion tank will do the trick. Will it really work? Any suggestions are greatly appreciated!

 

[AllanJ]

I would say, yes it would work. You would have a 1-1/4" line between the expansion tank and the plumbing fixture while 1/2 or 3/4 inch lines would be used everywhere else.

I think you would need an expansion tank of at least five gallons.

If the expansion tank is exactly half full of water when ready to flush, just before it empties out the water pressure at the fixture will be about half of what it was before. It is more common for the expansion tank to be 1/3 full of water when ready to flush giving less of a pressure drop (about 33%) just before it empties out. This gives 1-2/3 gallons for your flush (is that enough?)

Use an expansion tank with a bladder or diaphragm. Most tanks are like this. A non-bladder tank (e.g. tank not specifically intended to be an expansion tank) will lose most of the air if the flushometer takes too long to shut off and then the flushometer then won't work until you go through a calibration procedure to repressurize the tank.

Check the flushometer instructions for required water pressure.

 

[AllanJ]

deleted ................................

 

[rw4smithers]

Hey,
Thanks for the reply. I have yet to find or talk to anyone who has actually done this, but it absolutely makes sense to me. If there is anything else you or anyone wants to comment, I'm all "ears."

Again, thanks for the time and thought:smile:

 

[AllanJ]

One more detail, the expansion tank needs a 1-1/4 inch opening to connect to the (1-1/4 inch) plumbing with. This may be hard to find.