Ever see an F&T trap piped backwards (and how to best to correct this)? "After" pics posted.

ted_p

Part of my off season projects this year is replacing a number of crazy-oversized 2" F&T traps with 1" H-pattern traps, piped so that they can be tested in place. When I got to this one, my first reaction was "Holy Cow! They even put a 2" trap on a 1" line!!"




Then I looked a little closer and realized that the 1" line piped into the inlet at the top of the trap is the return!!!

I'm not sure what the guy who piped this was thinking; I don't believe that trap was doing anything good. The return (on the left in the first pic) is only a little bit lower than the main (on the right), so if I lower the replacement trap to put the steam into the inlet, the outlet will be a few inches below the return. Would this be OK?

Steamhead

No. The discharge pipe from the trap must pitch down. How much center-to-center distance is available between the main and return, without messing up the pitch? And are both connections 1"?

retiredguy

Is this steam installation in a residence or in a commercial building? If it is a commercial building was there any engineering done to make certain that using smaller F&T traps will allow the system to operate properly. Also, in some installations you can run a trap discharge line vertical a short distance depending on the piping and the steam pressure at that point. so, for me to answer or even attempt to answer your questions more information is needed.

EBEBRATT-Ed

@ted_p

Trap outlet should pitch down but on a commercial system with 5psi steam you can lift the condensate. Not ideal though, Trace the return line and the line the trap drains and see if you can relocate the trap. If you do lift with the trap put a check valve in the trap discharge.

ted_p

Thanks @Steamhead.

I'm not sure what the center-to-center distance is, I'll measure it in the morning. The connection to the main is 2".

Here's what it looks like with all the gypsy rig removed.



If it really has to fall from the trap outlet to the return, and there's not enough height for an H-pattern trap, I can use a straight-thru trap (like a Barnes & Jones FTI2015). In that case I'd put a tee with two ball valves, or a single 3-way ball valve in the line between the outlet and the return for testing.

EBEBRATT-Ed

@ted_p

Yes they make inline traps that will work fine for that job. It's seldom that you need a trap bigger than 3/4" for dripping a main.

It's strange but the way to size a trap for dripping a main is by figuring the weight of the steel pipe in the main and calculating the lbs of steam needed to raise the temperature of the pipe from (example 40 deg to 212 deg) lb of steam = a lb of condensate

Steamhead

ted_p said:

Thanks @Steamhead.

I'm not sure what the center-to-center distance is, I'll measure it in the morning. The connection to the main is 2".

Here's what it looks like with all the gypsy rig removed.



If it really has to fall from the trap outlet to the return, and there's not enough height for an H-pattern trap, I can use a straight-thru trap (like a Barnes & Jones FTI2015). In that case I'd put a tee with two ball valves, or a single 3-way ball valve in the line between the outlet and the return for testing.

Another possibility is the Sterling FT-69 series. It's only 3/4" though, but that may be enough depending on how much pipe it has to drip. Its center-to-center dimension between steam and return connections is only 1-3/4". See:

https://www.sterlcosteam.com/wp-content/uploads/2019/01/ts-sterlco-float-thermostatic-ft-69-3-15-final.pdf

Barnes & Jones used to make similar units but they no longer appear on their site. This was the 4xT series- I found an ad for the 1" 42T here:

https://www.amazon.com/Barnes-Jones-Part-Number-42T/dp/B00EKVKGGI

Then there 's the Watts (formerly Illinois) 7G-15, a 1" almost-inline F&T which looks like it would fit that job like a glove. The 3/4" version is the 6G-15. See:

https://www.watts.com/dfsmedia/0533dbba17714b1ab581ab07a4cbb521/12309-source

ted_p

@retiredguy:

This system is in an early '40s, eight story, 72 unit apartment building. It was originally a Dunham Vari-Vac system, which was converted to an ordinary vacuum return system in the mid '80s, or earlier (based on the age of the Shipco vacuum pump/condensate receiver). The original giant round steel boiler was replaced with a Weil McLain 1288 in '92. No engineering was done, but I just can't see the need for 2" traps to drip the mains, any one of which can handle significantly more condensate (at a 2psi differential) than that boiler puts out.

@EBEBRATT-Ed

The more I think about it, better to spend money on an "inline" (I couldn't remember the right name) trap and extra valve, than on the fancy piping required to make an H-pattern trap work properly.

Thanks.

Ted

EBEBRATT-Ed

@ted_p

Check with Tunstall Associates. I had bought many in lines from them a few years ago. One thing I recall is that in lines seem to have less capacity than other traps of the same pipe size.

Steamhead

ted_p said:

No engineering was done, but I just can't see the need for 2" traps to drip the mains, any one of which can handle significantly more condensate (at a 2psi differential) than that boiler puts out. Ted

If I were you, I'd use the minimum pressure differential the trap is rated for. This will make sure it does its job even without vacuum.

ted_p

@Steamhead :

Thanks so much for your trap suggestions; after comparing them all, I went ahead and ordered the Barnes & Jones 42T from Amazon.

The center of the return is about 8" below the center of the main. Sadly, I lose 5-1/2" of that to the bottom leg of the Tee, close nipple and 90, leaving the center of trap inlet only 2-1/2" above connection to the return.





While this is insufficient for an H pattern trap, the 42T will fit comfortably, plus it has the extra outlet port for my test valve, so it's a win all around.

Here's pics from 2 different angles showing where, after the trap, the main and return turn up through the deck to the basement level.

EBEBRATT-Ed said:

@ted_p

..... One thing I recall is that in lines seem to have less capacity than other traps of the same pipe size.

Great point! I just did a quick comparison of Sterlco F&T traps, and found that the 1" FT-92 (H pattern) has almost 80% more capacity than the inline FT-90 in the same size.

Steamhead

@ted_p , looking forward to the "after" pic.

The Steam Whisperer

I always find it interesting that even in the old days, the system designers ignored the recommended 15 inch drop into the trap that was there to ensure the trap ran at rated capacity, even on systems without vacuum. On the system, make sure the vacuum is fully established before starting to steam to ensure the trap can handle the full condensate volume. I 've seen a number of systems where they cycle the vacuum pump with the boiler, so be careful. These systems usually heat very poorly.

The Steam Whisperer

Oh, and I have seen traps piped in backwards. I came across a battery of about 7 traps all neatly installed next to each other. Someone had replaced one with the identical model and installed it backwards, even with 6 correctly installed examples staring them right in the face. FACEPALM!

dopey27177

Please see my response to all of the above as there a drawings and charts included' The Title will be Steam trap usage and installation.

Jake

ted_p

Steamhead said:

ted_p said:

@ted_p said:
No engineering was done, but I just can't see the need for 2" traps to drip the mains, any one of which can handle significantly more condensate (at a 2psi differential) than that boiler puts out. Ted

If I were you, I'd use the minimum pressure differential the trap is rated for. This will make sure it does its job even without vacuum.

As it turns out, I was unable to get that Barnes & Jones 42T on Amazon, so I started looking for alternatives with this advice in mind.

@Joe_Dunham ( Joe Strapoli of GS Dunham LLC), who took custody of the archive of Vari-Vac system build records following the break-up of Dunham-Bush, was kind enough to do some research and informed me that my system's mains were originally dripped with Dunham type 30-4, 1" F&T traps.



The above table, which I found in the "Dunham General Products Bulletin of Low-Pressure Steam Heating Appliances" in the Heating Museum, shows that a Dunham type 30-4 is rated to handle 500 lbs of condensate per hour, at a 2 psi differential. So in keeping with your advice, I bought a Mepco 42-515A inline F&T trap, which can handle 630 lbs per hour, at it's minimum rated differential of 1/4 psi.


Coincidentally, this almost duplicates the capacity of the 1" Sterling FT92-4-15, H-pattern F&T traps, that I'd already bought to drip the mains in the other locations where there's more headroom; I suspect that they have the same size orifice in their float valves.

Steamhead said:

@ted_p , looking forward to the "after" pic.

I won't have any "after" pics until the end of the month; the new Sterling H-pattern traps (which I was told would be delivered before the Memorial Day), didn't arrive until late on May 29th, so wasn't able get any of them installed before I left on the 30th. I'll get back on it as soon as I return, and post after pics as they go in.

The Steam Whisperer said:

I always find it interesting that even in the old days, the system designers ignored the recommended 15 inch drop into the trap.....

The design of my system bears that out. Because of the lack of height difference between the main and the return, there's no other choice for the particular trap that we're discussing here. But at least four of the other five traps that I'm replacing/re-piping are in places where there's ample room for the recommended 15 inch drop, yet they're all mounted tight up under the mains. And that is something that I will correct when I pipe those traps (more after pics to come).

I'm indebted to you for pointing this out, and to Jake (@dopey27177 ) for the excerpt from his book that he posted in Steam Trap Usage and Installation, which made clear to me the advantage of having a priming leg.

My apologies to all who posted, for being so slow to reply.

Ted

ted_p

I finally made it back into town last week, and finished this one on Friday.





We set the trap so that the outlet is level with the return in order to maximize the drop into the inlet of the trap (thanks again to @The Steam Whisperer and @dopey27177 for bringing importance of this to my attention). This gives me a seven inch drop from the inside-bottom of the main to the inlet of the trap. Although short of the recommended 15 inch drop, seven inches of water column still provides over a 1/4 psi of static pressure.

Steamhead said:

If I were you, I'd use the minimum pressure differential the trap is rated for. This will make sure it does its job even without vacuum.

And this trap (a Mepco 42-515) has a rated capacity of 630lbs/hour at a 1/4 psi differential, which is more than the 500lbs/hour at 2 psi rating of the original Dunham type 30-4, meeting @Steamhead's above suggestion.

I'll be posting pics of the other 5 conventional (H-pattern) traps that we installed in another thread. The the whole job was greatly improved by what I learned here. Many thanks to all who contributed.

Ted

Sailah

"We're having problems with our water heaters."

ted_p

Now my wife's asking me what I'm laughing at!

EBEBRATT-Ed

My eyes suck and I can see the arrow pointing down

Sailah

This is a new customer for us for steam trap monitoring, military hospital.   This pic was sent to me by the contractors yesterday.   They were also mentioning how they kept burning up pumps in their condensate tanks. 

Hard to believe you can be a steam contractor and not see this type of stuff,  especially since it's written right on the side of the trap in huge letters and an arrow.   They were good sports about it though. 

Fortunately the other 2 Sarco 2" traps are right side up.