Water hammer when boiler cycle ends....

Jack_2

When the heat cycle ends in my one-pipe steam system, there is significant water hammer at the Hartford Loop equalizer area. While the boiler is firing, the water level in the glass gauge is in the middle or above. However, when the cycle ends, the water level drops to the bottom quarter of the glass gauge and this is when it starts hammering. When I added water so that the glass gauge indicates 7/8 full, the boiler does not hammer when cycle ends because I'm assuming the water level stays above that quarter level point. What could be causing the sudden drop of water at cycle end? Is there anything else I should check for? Thanx for your responses.

Unknown

Sounds like your Hartford Loop

might be too high on the boiler . It is supposed to be piped at least 2 to 4 inches below the normal water line . When the water level drops below the water line , steam from the equalizer and condensate will meet - big hammer sounds . The LWCO ususally shuts the boiler down before this happens - if the Hartford Loop is at the right height .

Unknown

Ive also seen it happen on new installs

Sometimes we see all the water disappear from the sight glass after the boiler shuts down on a cycle . This was mainly on Peerless ECT oil boilers . Not sure what the cause was . Never had the banging noises youve heard though - we keep the loop as low as we can .

Jack_2

to ron jr.

You mean the horizontal pipe of the Loop should be 2-4" below the quarter-level point in the glass gauge? Then there will be no vertical drop at the attachment point where the loop connects to the boiler. But the real question is why the sudden drop in the water level at cycle end? By the way, I did'nt know boilers can hammer when they stop firing....!

Unknown

Sounds like you have a gas boiler ?

I know on past installs , there aint much room to install a Hartford Loop on a gas boiler - the Peerless 61 needs the tee only 5 inches above the lowest part of the boiler . How high is the tee compared to the normal water line on your boiler ? Do you know which brand boiler you have ? And yes , boilers can hammer at quite a few odd times in a cycle . Any chance you could post a pic of the piping on your boiler ? Is the equalizer pipe the right size ?

My pet theory on what happens to the water at the end of a cycle is that once the boiler water gets low enough while steaming , it hits a critical mass and just steams out past the level of the glass , even when the burners is off for a while . But I could be totally wrong .

Jack_2

to ron jr.


I experimented with the cut-in control and set it so the cut-out is at 2 1/2 psi. This seems to have eliminated the water hammer at the hartford loop-equalizer area at cycle end. It was originally set to 3-4 psi. So I don't think the piping is the problem. I'm assuming the lower pressure is not causing the water to drop as much in the sight glass when the boiler stops firing. With this new psi setting however, I do notice that the coldest area of the house does take a little longer to become warm with appx. 1 degree increase every 30-40 minutes. Is this normal? Also, there is a label in the cut-in box saying "cut-out is cut-in plus differential". What the heck does this mean?? I have a Weil-McLain model EG-55 gas boiler with no water heater. Thanx again for your responses.