Vapor Vacumm system flooding

Scott McGuire

I have an old Webster vapor system that had an H. B. Smith oil fired boiler that the owner said always flooded. We converted the house from oil to gas and installed a Weil Mclain LGB-6 gas fired boiler. All the original Webster parts are still installed. We ran the sytem after skimming and cleaning and had no issues. The system would make pressure and heat all the rads. The house would make temp and shut down. The system would than pull a good vacumm. Never saw an issue with the water line.

The owner has called twice to say the system flooded. We have a VXT feeder wire to the LWCO. Once the feeder added 20 gallons and yesterday again added 10 to the system. The feeder is set with a 4 minute time delay to allow condensate to come back. All the wet returns have check valves except for one which is fairly close to the Hartford loop tie in.

I was wondering if anyone had any ideas as to why the system would flood this way. Should there be a check valve on that one return. Is it possible the LWCO is being held down when the sytem goes into a vacumm. Maybe the system just needs a boiler feed pump instead of a feeder. I just can't figure out why when we run the system and observe it that everything seems fine and then a call from the owner comes in saying it flooded. (Overfilled). Thanks to the digital feeders which give us the gallons used. The system is running a #75 main line air vent.

Dave in QCA

follow-up questions

The question probably is whether the boiler is pushing water out while steaming or whether the current setup is causing the condensate to hang up.



What is your cutout pressure set at?  Have you tested to see exactly what the pressure is when the cutout switch opens?

Are all of the original Webster devices present?  Return trap?  Webster vent trap?  Webster Vent valve



You say you are using a Hoffman 75 for venting.  Is it located at the end of the steam main, or in the return piping.  Are you sure its a #75?, or perhaps a #76?



Also, it always helps to see pictures of the piping, devices, etc., so one can get a better idea of what you're working with.



Here is a link to a Webster booklet in the heating-help library.  http://www.heatinghelp.com/files/articles/1337/320.pdf

Scott McGuire

more info

The vAporstat set at 8 inches cutout and 2get cut in. Seems fine by the gusts. All Webster parts are there. Is a 75 vent for sure located at the vent trap. I will try to get some pics. Thanks for the help.

moneypitfeeder

pics are very helpful

Where in the return are you suggesting a check valve?



Sidenote, if there is a clogged wet ruturn it won't come back in a timely manner causing the autofeed to kick in and the flooding the boiler can happen when the condensate finally gets back. Does this sys. have a return trap/ air eliminator? If so, check the return lines directly connected across them and associated check valves.

clammy

Check for water seal

Check your boiler water line against where your drips and wet returns tie together ,make sure you have a water seal or that all these connection are well below the boilers water line .if they are not then this may be the issue ,i have ran into this a few times it is mostly due to a differene in boilers water level from the original boilers water line to the newer boiler.Usually the way to corret it is to fiqure the original water line and build a false water line to cover all those formerly wet returns and drips . Remove check valves from the returns and install a hartford loop make sure that your equilizer is properly sized and that the return lines are not  clogged.Last but least make sure your near boiler piping exceeds the manafactures specs most vapor systems perform best when the steam is dry .Hope this helps peace and good luck clammy