Vapor System Crossover Traps

Harry_6

Ok, this is one for the deep thinking theorists. Perhaps DH himself. Why does anyone suppose that one often sees end of steam main crossover traps installed what we would consider as "backwards," with the inlet end connected to the return and the bottom "outlet" connected to the steam main? Although this always seems like a mistake, I have even seen it shown this way in some, but not all, manufacturer's literature. It seems like steam entering below the valve would cause it to "hunt," constantly opening and closing as steam contacted the thermostatic element. So what do we think is going on here?

Jamie Hall

I doubt that i t would hunt -- there is no condensate available to a crossover trap to cool it off. It might crack open a bit now and then, but would reheat and close almost immediately.

JUGHNE

Would it stay closed longer in that hot spot, creating a vacuum in the system that may be desired?? WAG

nicholas bonham-carter

Maybe it doesn't matter which way the steam flows through the crossover trap. The element will still be exposed to the steam, and close.
One consideration would be convenience in checking the trap for leakage, by cracking the union nut, on the discharge side of the trap, and checking for steam coming out.--NBC

Harry_6

Those are all food for thought.

MilanD

Perhaps @Sailah could set up one trap like this "backward" on his test station and see how it operates vs. the regular setup. I'd be curious too.

arpitkakkar1

Fume hood is good vapor system you can try it, it can remove all vapor, moisture, and other biological agents from work place. these equipment used at huge level of work like research work or hospitals some more equipments are used in that works like bacteriological incubator, incubation chamber and etc.

Sailah

MilanD said:

Perhaps @Sailah could set up one trap like this "backward" on his test station and see how it operates vs. the regular setup. I'd be curious too.

Ask and ye shall receive

https://youtu.be/XI7uiHaT25U

MilanD

Sailah said:

MilanD said:

Perhaps @Sailah could set up one trap like this "backward" on his test station and see how it operates vs. the regular setup. I'd be curious too.

Ask and ye shall receive

https://youtu.be/XI7uiHaT25U

Thanks Peter!

Harry_6

Thanks a bunch! And now we know. One less question to keep us awake at night. Perhaps some are just installed wrong!

EBEBRATT-Ed

Really nice video's thank you @Sailah

Picture really is worth 1000 words

Jamie Hall

Nothing like a real life experiment - thanks!

Noel

I had a couple dorm buildings full of those. They were called "outboard" traps and since the union nut was on the orifice end of the trap, they were designed to be operated that way. The radiator traps were also all that way. My comments; they work fine but it was a b**** to get the cap on without the element falling sideways. I have no idea why they did this, but it was only for a short while in the early 1940s. I had a new building every 4 or 5 years from 1911 through 1960 with vapor systems in them, a veritable museum of vapor systems. The 1911 had a vari-vac in it (no longer complete) with 2 zones of outdoor reset on steam.

MilanD

Noel said:

I had a couple dorm buildings full of those. They were called "outboard" traps and since the union nut was on the orifice end of the trap, they were designed to be operated that way. The radiator traps were also all that way. My comments; they work fine but it was a b**** to get the cap on without the element falling sideways. I have no idea why they did this, but it was only for a short while in the early 1940s. I had a new building every 4 or 5 years from 1911 through 1960 with vapor systems in them, a veritable museum of vapor systems. The 1911 had a vari-vac in it (no longer complete) with 2 zones of outdoor reset on steam.

Where is this? It would be a prime location for a steamheads tour!

Noel

It is active residences, so no tour. I'm not there any longer. I took Steamhead through there once.

http://studynh.com/colleges-universities/colby-sawyer-college/

MilanD

This would purely feed my curiosity... There is reading Mr. Holohan's and other old books, but then there is seeing it in person working...

Steamhead

Noel said:

It is active residences, so no tour. I'm not there any longer. I took Steamhead through there once.

http://studynh.com/colleges-universities/colby-sawyer-college/

That was one of the most interesting building tours I've taken.

What are you up to now, Noel? Been a while...............

gerry gill

Sailah said:

MilanD said:

Perhaps @Sailah could set up one trap like this "backward" on his test station and see how it operates vs. the regular setup. I'd be curious too.

Ask and ye shall receive

https://youtu.be/XI7uiHaT25U

Very cool video Peter. I have often wondered if it mattered as to the orientation of the crossover. Now i know. Thanks for the video. I'm never to old to learn something new

Dave in QCA

There was a thread on here about a year ago with a fully intact vapor system that had outboard traps on the radiators. I forget the maker, but it seems like it was Illinois, but now I can't find the information on it. The system that I recall, whatever it was, when reading the rationale on the traps orientation, it was all about the fact the traps close around 180F. In a conventional setup, the outlet corner of a radiator will never fully heat because of the trap closing early. However, with the outboard installation, it will close when steam hits the element, but as soon as it closes, the steam is separated from the element, the element cools, then reopens. Or... as the video clip shows, the traps closed most of the way, but remained open just a crack with steam leaking through, to keep the trap closed, almost.

Personally, it seems to me that in a crossover situation, the outboard setup would not be desirable. The only thing necessary is letting the air out of the main, as opposed to keeping that last foot of the main as hot as possible.

Noel

Steamhead said:

Noel said:

It is active residences, so no tour. I'm not there any longer. I took Steamhead through there once.

http://studynh.com/colleges-universities/colby-sawyer-college/

That was one of the most interesting building tours I've taken.

What are you up to now, Noel? Been a while...............

Not much new. Lisa found us a house built in 1710 and we bought it. Ripped out the steam boiler and repiped it the way I want it. Had a fellow wallie plumb us a new bathroom that son Seth remodeled. Seth is living in our other house in Sutton now.

I ride ATVs with my kids and grandson in my spare time. I have a Polaris RZR.

Steamhead

Cool! One of these days I'll have to get back up that way. Been a long time, and I'd love to show The Lovely Naoko that part of the country..