Your experience skimming Slant Fin with built in skim trough?

Woven

Hello Slant Fin aficionados!

Looking for input from those who’ve skimmed boilers with Slant Fin's built in tapping about whether you’d vary what Slant Fin’s manual says to do.

You can see pretty much the set up I’m working with on this old post picture from tomsloancamp (click here to view)

As in this pic, I’m working on a boiler with no tankless heater, aka “normal” in my view. (Relevant because Slant Fins with a tankless/heater provision have a different skim pipe set up). There’s a skimmer that has been built into the casting, setting up for skimming through a 3/4” N.P.T. 

1. Slant Fin reccs:  Remove skimmer plug. Install 3/4" skimmer valve, elbow and length of pipe. Complete skimming. Drain down to level of skimmer tapping, remove valve, plug skimmer tapping.
2. First alternative: From a guy who hates the Slant Fin trough. Says to use a larger diameter pipe. Says no need to remove elbow, etc. after skimming and just leave it piped for skimming. (Obviously I’d need to plug or put a valve on the added piping.)
3. Second alternative: Another person talked about the built in skim taping like it didn’t exist. Approach was to treat the boiler as un-skimmable if left as-is, or to remove the built-in skim tapping and put in something else. (I didn’t tease out exactly what he’d replace it with, the skimming set up was already just an interesting thing we were chatting about.) 

What have you done when skimming Slant Fins with the built-in trough? 

I know exactly what to do if I follow the manual directions, and yet two reasonably experienced people have said they’d do things differently. Thing is, I’m not sure how much attention they were paying and if they were going off of bad assumptions. So, of course - here I am!

mattmia2

What ever you linked to is not a skim port, it is the hartford loop and and some other tapping on the boiler that has been plugged with a nippe and cap. The skip tapping has to be above where the sections of the boiler connect together but below the top of the casting so the oil from all of the sections can float on top of the water that is trickling out the skip pipe.

Woven

In the linked picture, the plugged nipple to the right of the sight glass is the built-in skim tapping. It's the specs of this type of Slant Fin.

mattmia2

oh, i see, there is something weird about the internal design of that boiler. the sticker that is blurry and cut off looks like it explains it. if that is where they(and especially @The Steam Whisperer ) say to skip, use that skim tapping.

Woven

That would eliminate #3 (which matches my inclination), and still leaves the question of #1 vs the two options of #2 alternative as potential things to do. We'll see if anyone who's skimmed these chimes in!

(Yes, the "weird" factor is the trough)

STEAM DOCTOR

Skim through the trough. Works fine. No need to overthink this.

Woven

Yup, agree. Curious about your thoughts/experience with the options I was considering.

ie: Have you removed the skimmer valve, elbow and pipe after completing skimming, or left them on

And have you stuck with the 3/4" or gone bigger?

mattmia2

The tapping is 3/4", no point in making it bigger(there are certain boilers where you have to reduce the tapping to raise the water level but this isn't one of them). you can leave the valve and ell on and just put a cap on it as long as it isn't in the way of anything else. you should have the flow adjusted so it is just a trickle along the bottom of the nipple anyhow.

The Steam Whisperer

Actually, you can do more than a trickle flow because the internal dam inside the boiler is about 6 inches across…. much bigger than the little bit of pipe cross section in typical skim tappings. You are not skimming at the bottom of the nipple, the 3/4 inch nipple is just the drain. You can get a good skim on these boilers in 20 to 30 minutes rather than the hours for most boilers. I am having a welder make up some nipples with a dam across them in the middle to provide a much wider skim edge like the Slant Fin boilers.

STEAM DOCTOR

Pics pics pics please. Would love to see