Up-Feed versus Mechanical/Pumped Return

NewlyPuzzled

Is it possible for our system to be an 'Up-Feed' *and* a 'Mechanical/Pumped Return' Parallel Flow System???



Would it be correct to say 'Parallel Flow Up-Feed Mechanical (pumped) Return'???



With this type of piping application, is there still a need for air vents on the supply main and/or the risers?



This is on a 12-unit apartment building (3 stories and a basement), with a Weil-McClain 480.000 Btu boiler.



Thank you for any help you can provide!

Paul48

Brian

It's a one-pipe steam system, and those are characteristics of a system.Unless you start posting some pictures, we can only guess and assume you are properly identifying things. Show us some pictures of the near-boiler piping and the ends of the mains as they transition to the returns.

nicholas bonham-carter

Getting the air out

No matter what sort of steam system, there is always the need to allow the air to escape so the steam can enter the pipes and radiators. In 2-pipe systems there are steam traps which release the air, but in your case, it can only be the main air vents, and lastly the radiator vents which allow the escape of air. This air removal cannot be done by the radiator vents alone, without paying the gas company extra to squeeeeeeze the air out of the constipated little openings of the radiator vents.

As you have a 1-pipe system, then you probably have a parallel-flow system, in which the pipes above the boiler start out as high as possible, and continue around the building, feeding various risers, sloping down, until they arrive back close to the boiler (dry-return), and drop down below the waterline of the boiler(wet-return).--NBC

NewlyPuzzled

Confused

Okay, thanks NBC, that helps a lot. You have confirmed my thinking, but; I was just really confused after looking at all the schematics.



On the schematic for the 'Mechanical Return' there are no air vents on the supply main. There is a "Y" strainer and a F&T Trap, which we *do* have, but no air vents (other than the one coming out-of the condensate holding tank - we have a vent on ours).



I was just confused on whether we do in fact need air vents on the main since we have a 'mechanical return' application.



The way you describe the radiator air vents trying to get the air out is exactly what we are experiencing!



Both the steam mains end at an F&T Trap, drop down and run to the condensate holding tank and are pumped back to the main condensate tank.



Thanks!

NewlyPuzzled

Will Do

Okay, will do...thanks!

Paul48

You're OK

The F&T trap is used on a mechanical return, and has the ability to vent large amounts of air. Do some searches for F&T traps and you'll find lots of info about them. There is site that will show the internals, and how they function. Let us know if you don't find anything, and we'll locate it for you.You may be in better shape than you thought, but we still need pictures.The size and placement of the trap is important and may be a source of problems if not done correctly.We'll seek the help from the experienced steam pros, once we get a look at that configuration.

nicholas bonham-carter

F&T trap

That sort of trap must then have a double exit, one for condensate back to the tank, and another for air. if the element inside is not working properly, then the air will not be able to get out. High pressure could also prevent it from working.--NBC

Paul48

nbc

His description leads me to believe it is installed in the wrong position, but we need to see it.

NewlyPuzzled

Thanks!

I wanted to thank you both for all your help with this. Unfortunately, the owner has decided to go in a different direction. He has decided to let the mechanical company decide what needs to be done and not heed my advice. So, I am backing-off of the project and letting them figure it our on their own. I may very well be leaving my position and residency at the building as well. Right now, we are experiencing wild temperature fluctuations, water hammer, water in radiators, etc. I really have no desire to continue to manage or live in a building that is operated so poorly!



Thanks Again,



Brian