Old Church combined 1 and 2 pipe systems. Needs false water line.

Dave52

1st a little history. Original built 1921 with 1 pipe radiation (parallel flow) and 2 pipe with preheat and reheat Venco coils. The wet returned to the boiler below water line. The 2 pipe dry return to a in floor condensate lift station to pump back to boiler on an automatic float.

In the one pipe return piping, there were no horizontal check valves in drops to wet return from end of supply mains, just a back and forth horizontal piping before dropping into wet return.

Next thing was an expansion. Added on in 1928 expansion. Again same systems and equipment as 1921 original except now the horizontal drip leg piping taken out and check valve put in its place (horizontally about half way down) as it dropped into wet return. The dead men did a good job combining both buildings into one boiler room. They added a second locomotive style boiler, larger steam header for the increased load.

At that time pneumatics were controlling open/close on heat valves, face and bypass dampers in air handler's and air dampers to different area's.

In about the late 1930's a major control company added pneumatic (modulating) operators to all one pipe radiation and automatic control of air handler's.

From the older member's (who can remember) This was the start of problems with the system.

At some point the boiler room got redesigned with scotch marine boilers and rehab of condensate return system in same room. Now I have a boiler feed tank with one feed pump per boiler on a 150. A combined 6" return pipe, with air vents, that combine all returns into one pipe. The 6" drains into (master traps) F&T and Bucket trap, outlets rise up (12") to a mechanical lift station that pumps it back to feed tank.

Fast forward last fall (2023) when we got involved.

Made a bunch of minor changes and adds to get a better heat distribution. The very 1st thing was lower the steam pressure at the vessels to modulate fire at 1.75#. Was operating at 7#. 2nd was all radiator valves stayed wide open if pneumatic and open/close if manual. 3rd was fix all the radiator and EOM air vents

Of course church has been thru many contractors, engineer's as they keep throwing money at it with no fix to the actual problem only symptoms.

In creating the false water line to get back the wet return, Eventually I will be separating the 1928 side from 1921 side as if there were two independent boilers cycling on space temperature for each side.

Because this will act like two separate systems I would have to create two separate false water lines.

The 1921 side all the EOM except one drops into pipe tunnel and then rises 32" for a horizontal run into boiler room. The one exception is the last EOM which has a wet return at same level as the tunnel wet return.

The 1928 side all the EOM will drop thru a check valve and into a pipe tunnel return main. This main is horizontal to the boiler room. Approximately 10" higher than the 1921 side returns.

Trying to find the "B" dimension has been a challenge. On the 1921 side I don't have the 60" minimum needed.

The check valves that were added on the 1928 side, I would speculate are there to keep the wet return back pressure from raising the level up in the riser until there is enough condensate in the riser pipe to overcome the pressure to move it thru. This should reduce the need for a large "B" dimension.

On the 1921 side there never was the "B" dimension that all the books say you should have. But the system worked fine for several decades.

Yes I will have an equalizer line to the top of both false water line tanks.

Now for the big question:

Getting the correct height calculated on both false WL tanks is proving to be a challenge. Needing additional brain input.

Mad Dog_2

Pictures & Sketches please. Mad Dog

Dave52

Mad Dog_2

Could you get specific on what pics and sketches would be beneficial. Have lived with this system thru one heating season making minor changes knowing what major changes need to be made. Have tons of pictures and details.

Steamhead

Nothing wrong with having two FWLs for different parts of the system. We have a building like that and it works great. Just make sure 1- that the wet returns are actually filled with water, and 2- that there is enough "A" dimension at the ends of the various sections.

Dave52

That's one of the big questions. According to the measurements there never was enough "A" dimension on the 1921 side.

With the check valves in place on 1928 side it appears to allow a lower "A" dimension.

Mad Dog_2

The equipment. Mad Dog

Dave52

In the process of trying to get the actual dimensions of lowest horizontal main to boiler room floor. Not concerned with boiler water level. Condensate return uses a lift station and feed tank to get condensate back to boilers, hence the need for false water lines to recreate wet returns.

Dave52

New update question.

Got everything calculated to this point. My only unsure of is the actual diameter (Holding capacity) of the vertical tank. If you look at the total EDR of the existing wet return size and keep the diameter at this minimum or larger I would estimate you would be good. I had figured with a 4" and a 2" wet return, an 8" diameter tank should be good.

Thoughts???