Condensate piping question

Chuck_17

A condensate return for a 2 pipe system (in a church) drops from about 7' down below a floor (across a doorway) then back up to about 4' above the floor then flows by gravity back to a feed pump receiver.
Should there be an air line up over the doorway?
There is currently not one.
Does it make any difference with the end of main contraction in the photo? The condensate pipe goes to the left about 10 feet before it drops down. The condensate pipe after the drop does receive condensate from radiators.

nicholas bonham-carter

I'm not sure about the condensate return line configuration, but the air vent on that ham is surely too small, and probably could be removed altogether if the crossover traps are working properly.
That vapor system needs very low pressure to function properly, (6 ounces, controlled by a vaporstat, and verified by a 0-3 psi gauge).
The condensate tank could probably be eliminated, as the system was likely installed without on originally.--NBC

Pumpguy

To answer your question specifically, the answer is YES. This is called a "DOOR LOOP" and is SOP for the conditions you describe.

This is illustrated on Page 95 in my copy of Dan's book, THE LOST ART OF STEAM HEATING.

I am sure if you Google "Door Loop piping" , you will find examples online as well.

Pumpguy

See attached file

Chuck_17

Thanks.
I know what they will say - "It has worked fine for ___ years"
The down stream side has a pipe that could have been the air loop (cut off and caped). There is no sign on the upstream side though.
It was uncovered during a renovation. The pipe below the floor (in a damp low 6" crawlspace) was leaking and has been replaced.

Chuck_17

BTW - If you look at the first photo, it looks like the end of the condensate in question has an "air" connection to a condensate high up which should be the end of the condensate which goes around the other side of the church (to the right). That being the case - perhaps the air in our upstream condensate has an escape route.
The condensate that goes the other way around also has to go around a door. Now I have to go back and see what happens there.

Pumpguy

The door loop arrangement shown should be used for steam supply piping and on the return side of a vacuum return system. The upper air pipe will carry the vacuum over to the upstream side of the door loop. The lower pipe becomes a simple wet return.

When the returns are at atmospheric pressure, the air can be vented to atmosphere just ahead of the upstream side of the lower part of the loop. The lower side again becomes a simple wet return.

Dave in QCA

NBC, the device we are looking at is a Dunham Air Eliminator. The vent on it is supposed to be open to the atmosphere. Its application is on the return piping of a 2-pipe system. It contains a float that closes if boiler pressure gets high enough to back condensate up in the return piping on a gravity return system. On a system with a condensate receiver tank and pump, it serves no purpose. The location that it is in, at the apparent beginning of a return line running to the left, and an upper return line going to the right, is a mystery to me. Perhaps the venting at this point has been inserted to compensate for the lack of an air line up over the door? At any rate, someone was improvising to say the least.

Have there been major modifications in the past to this system. More pictures, showing more of the system were certainly be helpful.

Dave in QCA

Chuck, I was just spending more time looking at the original photo and discovered the air line that goes from the lower condensate pipe, which goes under a door to the left, and the upper condensate line located up high, that runs to the right. Assuming that the upper line is properly vented, that would serve as the air line, which would normally be routed up over the door. Reading back, I see that you concluded the same thing.