Wet Return/False Water line Question...

SteamCoffee

Hi Folks, been studying LAOSH and such and am trying to figure a nagging question out. Mainly this; Page 28 of LAOSH says that when you turn a wet return into a dry one,by (ie swapping boilers) you create a "storage tank" for condensate while the boiler is firing. Why is this? Why would the condensate not just run down to the Hartford Loop? Is this because the Wet Return is not normally pitched down? Why make the False Water line if the condensate can just run back by gravity? Can seem to find out why this would be a problem. Thanks!

JStar

Water line

The idea is that if you don't have the proper A Dimension, from exposing a wet return, you'll need to prevent steam from causing water hammer in the horizontal condensate lines. You use the false water line to "water seal" the steam, and prevent it from entering the return.