New Pressuretroll Setup-Comments Welcome

cubicacres

We just had a boiler tune-up for our single-pipe steam system and the local contractor put both our gauges & our 2 city required 0-30psi pressuretrolls on the single brass pigtail we had since the 2nd pigtail was taken away with the new boiler install & we haven't added another one yet (they didn't have one in their truck).

We have the top pressuretroll set at cut-in 0.5psi with a 1.0 differential, and that's the top one in the 2 photos now. The 2nd one is still set at 2.0psi cut-in & 1.5 differential as a a safety, we think. The pigtail was very clogged after 5 years of operation, so we're glad we we looked at it & removed the mud.

We're concerend that since they're both on the same pipe pathway now, will the higher 2.0 cut-in one become the operating controll now since it has a straight shot, or will the steam rise & still keep the operating one with 0.5 cut-in & 1.0 differential controlling the boiler? We'd prefer the lower operating pressure. The technician reccomended setting both at the same 2.0 cut-in & 1.5 differential since he didn't know which will get the steam first, so we're wondering about this. Any thoughts?

ChrisJ

A contractor did that?

mattmia2

ChrisJ said:

A contractor did that?

A contractor that didn't seem to understand that the static pressure in a connected vessel would all be the same.

Jamie Hall

ChrisJ said:

A contractor did that?

Sigh...

However, it's not a matter of who gets steam first. In fact, with a pigtial in there, neither one of them will get any steam at all. We hope. As to who gets pressure first, that is a meaningless question, and betrays not understanding some pretty basic physics. Since there is no flow, there is no pressure variation anywhere in the assembly -- the pressure is the same everywhere in there, and any changes in one place (the one place it can change -- at the pigtail) are communicated nearly instantly to everywhere else. In fact, at the speed of sound -- about 1,000 feet per second.

So... rest easy. Both pressuretrols will see the same pressure, and the one set lower will trip first, just as you want it to.

KC_Jones

To me, it doesn't make much sense to put a back up safety on the exact same connection as the primary safety. If one pigtail clogs, they both stop working.

Also, mounting it sideways like that is just chancing filling the device with crud. That is why the previous comments are asking if a contractor did that. We, as simple homeowners, are in complete disbelief of what we are seeing there.

I am not familiar with codes in your particular area, but I believe some areas even require the back up safety to be on a different tapping in the boiler. Perhaps someone with knowledge of your local codes can chime in on that.

ChrisJ

Jamie Hall said:

A contractor did that?

Sigh... However, it's not a matter of who gets steam first. In fact, with a pigtial in there, neither one of them will get any steam at all. We hope. As to who gets pressure first, that is a meaningless question, and betrays not understanding some pretty basic physics. Since there is no flow, there is no pressure variation anywhere in the assembly -- the pressure is the same everywhere in there, and any changes in one place (the one place it can change -- at the pigtail) are communicated nearly instantly to everywhere else. In fact, at the speed of sound -- about 1,000 feet per second. So... rest easy. Both pressuretrols will see the same pressure, and the one set lower will trip first, just as you want it to.

1 pigtail to rule them all?

Not to mention the control laying down creating a great dirt trap.

mattmia2

The controls should be on fittings such that they fed from the bottom and are mounted vertically, that control should not be laying on its side.

The pressure within that piping will all be the same, the controls will both see the same pressure.

You can make a trap out of tees and plugs such that it serves the same function as the pigtail but you can just remove the plugs to flush it out or check to see if it is blocked instead of having to take it all apart. That might be a good upgrade if you are having trouble with it clogging.

If you want the second pressuretrol to be an effective safety device it should be a manual reset limit control that requires a reset button to be pressed to restart the burner if it were to reach the limit. As it is now it would just start operating off the higher pressure pressuretrol if the operating control failed so that failure would go unnoticed. The code may not require manual reset since residential code usually doesn't require the secondary control to begin with and it was some local or state level addition but in order for it to act as a safety control it should be manual reset.

EBEBRATT-Ed

It's simple.

It's a hack job

Jamie Hall

Oh I quite agree, @ChrisJ and @KC_Jones . The various pressuretrols or vapourstats or whatever should be on separate pigtails and should be on separate tappings. No argument there.

I was addressing the specific question, though: "We're concerend that since they're both on the same pipe pathway now, will the higher 2.0 cut-in one become the operating controll now since it has a straight shot, or will the steam rise & still keep the operating one with 0.5 cut-in & 1.0 differential controlling the boiler?".

cubicacres

Thanks for the comments. For today until we can improve it, we'll leave it if both are working ok as a 0.5-1.5 psi single pressuretroll. The city inspector is stopping by tomorrow-we'll see if he has the knowledge to have a preference-we seem to be the only ones (including city inspectors & contractors we hire) apart from the folks here at heatinghelp.com who ask these questions or notice things on our boiler. Maybe we're spending too much time on heatinghelp.com with you guys We can buy that second pigtail & some short iron piping to put both pressuretrolls & the 2 gauges in a better position eventually, similar to where they were before they moved them to tighten the wobbly antler up
. Too bad someone with a truck full of steam parts isn't in the area we could pay to make a few changes & be all set

cubicacres

Questions that remain are: do we buy another pigtail (straight or angled) one? Do we need another boiler tapping for the 2nd pigtail & pressuretroll, or can we antler it out similar to the old setup in the photo just above?

Steamhead

cubicacres said:

........... Too bad someone with a truck full of steam parts isn't in the area we could pay to make a few changes & be all set

Travel time would be a little much

mattmia2

See how @New England SteamWorks made traps out of fittings instead of using a pigtail, this is easier to maintain:



You Ideally would find another tapping for the redundant control. There frequently is an unused tapping in the top of the low water cutout.

Jamie Hall

I honestly would much rather see separate tappings, but... you can antler it, sort of like the old one, if the tapping you are using is above the water line -- and thus much less likely to clog up. If you do, though, it would be much better to go up, then a T and go off both ways (left and right) and set each pressuretrol on a pigtail going up again. One of them could be on a leg of a T which then went on to attach a pressure gauge. Maybe it's just aesthetics, but I have to admit I don't really care for the one in the more recent picture...

cubicacres

Thanks for the advice everyone. We decided to return to our original configuration today to keep those pressuretrolls raised up. Wires are a little sloppy, but hopefully will work ok until we get another pigtail & find another tapping or antler it.

mattmia2

You could tee off the tapping that the relief valve is connected to and put the secondary pressuretrol there.