F&T trap

JHK

I saw this the other day. This is a district heating system and the steam is being controlled by a modulating steam valve feeding 2 coils in a Airhandler. The bottom coil’s F&T trap’s outlet is obviously below the condensate line. The steam pressure being fed right before the valve is between 12-15 psig from what I saw. There are no gauges on the condensate return side to see what the actual pressure is at the trap. I was just wondering what you guys think about it. 

EBEBRATT-Ed

Steam pressure is used to lift the condensate. It's done all the time. I's Not the best way and not the way at all if the coil is subject to freezing temperatures. I would use a check valve on the trap outlet but I guess that is what the inverted loop is for.

Mad Dog_2

Is there a specific reason it runs at 12-15 psi? Is it a high lift? Specific equipment requirements?  Or someone just jacked it up?  Just curious 🤔?   Mad Dog 🐕 

JHK

I don’t know exactly why it runs at such a high pressure. I have to download the manual for the equipment specifications. There are steam coils 5 stories up from where this one is and it works off the same steam pressure reducing station as this one. 

EBEBRATT-Ed

@JHK

You have two choices. Experiment during cold weather and find the lowest pressure that delivers the heat you need.

or

Find the original specs or the engineer that designed it. Not unusual to run commercial steam at higher pressures. But the lower the pressure you can run and still deliver heat will make the system easier to control The height og the coil above the boiler makes no difference to the steam. Its strictly pipe size and load

JHK

Ok, good info.

JUGHNE

You might be leery of Engineer specs.

For instance, I have a print that was made for construction use, that states to run the boilers at 15 PSI.

These boilers are fitted with 15 PSI relief valves as stated on the same print.........

They actually run at about 5 PSI.