Water Hammer at End of Cycle

djthx

I noticed water hammer at the end of the heating cycle on GB200 4L.  The slight, almost melodic gongs (about 3 - 5) were generated around the Hartford Loop area.  I installed the piping according to the manufacurer's specs, and they call for the center line of the HL to be 2" below the Normal Water Level.  Since the HL piping is 1 1/2" (the header is 2", the equalizer and HL is 1 1/2", and the return line is 1"), this meant that the top of the HL nipple was only 1 1/4" from the NWL. 



After re-reading "We Got Steam Heat", as well as reading a lot of Pro postings on this site, I decided to drop the HL a little lower..  (The top of) the HL is currently 2" below the NWL.  So now, if I drain the return line, the boiler water level drops to 1" below the "Lowest Permissible Water Line" or about 1" high at the sight glass.  However, I'm still getting EOC water hammer (though it's barely noticeable)..

    

The GB200 4L is a small boiler.  The NWL to the crown is only 9 1/2".  I've read some postings which suggest to put the HL at slightly below the water gauge.  But in my case, this will mean having only about 4" to 5" of water level left in case of a return line leak.  Should I leave well enough alone (the rest of the system is operating great), and live with this almost unoticeable sound?  Or should I drop the HL some more?

 

Unknown

Water Hammer

Why don't you post a picture of your Hartford Loop piping maybe we can see something that might cause this problem. Have you considered possibly using a Gifford Loop?

- Rod

djthx

Near Boiler Piping by a Newbie

Here are some pictures of the used HB Smith GB200 4S I installed earlier this year.  Looking at the boiler from the front, the Equalizer is on the right side, and the HL is connected to the back of the Equalizer.  I installed a drop header and am glad I did.  It was tricky to connect the system to the existing main.  But I'm sure it would've been that much more difficult if it wasn't for the flexibity that the drop header's extra joints facilitate.   I used 2" for the riser & header (I calculated steam velocity at close to 16 f/s), and 1 1/2" for the equalizer.  As this is my first installation, I appreciate any comments.

Unknown

You need Steamhead's Opinion on this,

Hopefully Steamhead or Charley from W Mass will see this as they are both familiar with Smith installations and maybe able to offer some suggestions.

The large elbow going in the Hartford Loop I would wonder about. It maybe better to use a bushing on the tee and use an elbow and close nipple the same size as the return going into the bushing/ tee. There was someone else that used a large elbow and was having similar problems as you are having though whether this was due to the large elbow I'm not certain. Just a thought

- Rod

djthx

Can a larger Hartford Loop elbow cause Water Hammer?

Thanks for your comment.  I originally planned to put a 1 1/2" x  1" tee, with a 1" close nipple and a 1" elbow at the HL, which would then tie into the existing 1" return line.  However, I followed a Smith rep suggestion which was to make the 1 1/2" to 1" transition after the HL.  Logic holds that the water flow in the 1" return line can't ever entirely fill the 1 1/2" HL elbow and nipple.  At the EOC, when the water level is at its lowest, maybe steam is getting into the loop?  But then won't this be an issue of lowering the HL some more?  Perhaps some other Pros can lend a thought?