Pigtail setup

vinceM

Evening all. I was watching some boiler vids on you tube and picked up on a recurring theme. Most of the vids had boilers with this setup: gauge/site glass connected to a pigtail that connected by antler to what looked like a low pressure gauge next to a Pressuretrol next to a Vaporsat. An impressive setup. My boiler doesn't have a Vaporstat and the gauge glass is far removed from the pigtail with the Pressuretrol.
Should I reconfigure my set up????

Thanks

Fred

The site glass is never connected using a pigtail. I would say that is physically impossible. You certainly can put a Tee on the top of the Pigtail and use a couple elbows and couplings to mount your Pressuretrol and Low Pressure Gauge (0-3 PSI is most accurate). If you want a vaporstat or feel th it can give you better control of the Cut-In and Cut-out pressures (it certainly will if you need to lower pressure) You can mount it on the pigtail with the new gauge and mount the Pressuretrol on a different pigtail, elsewhere on the boiler. The Pressuretrol will act as a backup if the Vaporstat should fail. They all need to be wired in series with your other safety devices. Mounting it on a seperate pigtail ensures that it will be a true backup since pigtails can get clogged and having both the Vaporstat and Pressuretrol on the same pigtail minimizes the value of a good backup. Also, if you do reconfigure, use a union on the piping for the pigtail so that you can easily remove all the devices without having to take each one off individually. Your old 0-30 PSWI gauge must remmer as well due to municipal codes.

vinceM

Understood. As a reference please look at this video from Gerry Gill. In YouTube search type in: "boiler water feed issue". I'm not saying Gerry put this setup together, it appears in a video posted by Gerry. At 0.43 seconds is when you can first see the setup.
Let me know what you think.
Thanks Fred.

Fred

@vinceM , where's the link to the video?

BobC

Here it is -

https://www.youtube.com/watch?v=XsAG_cmv2Iw

Bob

vinceM

sorry for the delay. Yes, Bob got it.

vinceM

I think I can see a Tee behind the gauge glass as the line exits the boiler. The angle makes it hard to see. I guess my specific question is since I have seen a few of these similar setups is there an advantage to it?

Fred

Thanks @BobC . @vinceM , I do see the pigtail mounted above the sight glass. I would guess there is a brass Tee mounted on the boiler before the sight glass and an equal length nipple on the bottom fitting or maybe the gauge fitting has a tapping. They come in a number of configurations. That certainly will work but if you already have a boiler tapping with a pigtail on it, I'd be inclined to use it. In the configuration in the video, they may not have had other tappings above the water line of that boiler, IDK, but that would be a bit more cumbersome if/when you need to remove the sight glass fittings.

Jamie Hall

Pretty much anything goes, provided it conforms to a few basic rules...

The gauge glass must be connected, through its isolation valves, directly to the boiler, top and bottom.

A float type low water cutoff, ditto -- and frequently is connected together with the sight glass.

A probe type low water cutoff is place in a tapping or T at the desired level; frequently a separate tapping in the boiler, but in principal it could be in a properly threaded T in a gauge leg in parallel with the sight glass.

Any pressure gauges or pressure controls should be on pigtails, to protect them; they may also have snubbers. If there are two or more pressure controls, they should be on separate pigtails, but a pressure gauge can be on an antler arrangement with one of the pressure controls.

Pressure gauges and controls often are tapped into the boiler well above the water line, although they can be tapped into the top of some float type low water cutoffs. However, steadier and somewhat more reliable results can be obtained if they are tapped into the upstream end of a drop header, instead.

In any event, pressure gauges, pressure controls, and pressure relief valves must NOT have any means of isolating them from the boiler.

vinceM

Great info. Thank you to all for the responses

Fred

THe biggest advantage to having the low pressure gauge and the primary pressure control on the same pigtail is it allows you to see exactly what the pressure control (Pressuretrol or Vaporstat) sees. The 0-30 PSI gauge, while required by code, is useless on low pressure systems so it really does not need to be on the same pigtail and can stay wherever it is.

vinceM

Thank you Fred.

Dean_7

Just a homeowner but here is mine.

SWEI

Consider adding an isolation valve between the low pressure gauge (and Vaporstat, if present) and the rest of the system. This will facilitate any future needs for pressure testing and blow-down.

Steamhead

SWEI said:

Consider adding an isolation valve between the low pressure gauge (and Vaporstat, if present) and the rest of the system. This will facilitate any future needs for pressure testing and blow-down.

Would that meet Code?

JUGHNE

If the existing original P-troll, if still installed and wired in series, was on its own pigtail, than that would seem safer. IMO

Just like a water pump...don't want to isolate the pressure switch from the pump making the pressure.

SWEI

No valve between the boiler and the safety limit (Pressuretrol) or code-required 30 PSI pressure gauge. I'm suggesting a valve between the boiler and a second, operating control (Vaporstat) to isolate it and the low pressure gauge from the rest of the system. Is that a code issue?

Steamhead

It could be. The whole idea of having two controls is that if one fails, the second one should work. But putting a valve there would defeat the purpose of having two controls. In effect, if a knucklehead left the valve closed, it would be an intentional failure.

JUGHNE

Could we say that the original safety controls/gauge are still there and cannot be bypassed and the low pressure devices are just for convenience and energy efficiency, such as a programmable T-stat might be?

And the additional last hope PRV is there, unless the same Knucklehead put a plug in it, (which we have all seen done).

While on the subject, will code allow a valve to isolate the pressure expansion tank on HHW boilers? sure is handy though.

Steamhead

JUGHNE said:

Could we say that the original safety controls/gauge are still there and cannot be bypassed and the low pressure devices are just for convenience and energy efficiency, such as a programmable T-stat might be?

And the additional last hope PRV is there, unless the same Knucklehead put a plug in it, (which we have all seen done).

Not sure. I'd get a ruling from the local Code authority on that.

JUGHNE said:

While on the subject, will code allow a valve to isolate the pressure expansion tank on HHW boilers? sure is handy though.

I believe so. I've seen this on countless diagrams and countless jobs. I suppose an expansion tank is not considered a "safety" device.

JUGHNE

In my area there is no local code authority other than for the larger boilers that are subject to annual inspection by state requirements. This inspection is also carried out by the insurance and the state will use their approval. The Hartford Insurance wants to see LWCO working, high limit temp controls working, see that the PRV is there, sometimes want to see it open and flushed, and inspect the interior of firetube boilers for safety issues. Those are the only key points I have seen.

I believe it is a good thing that an outside "expert" has a look, as it requires the boilers or large water heaters to be drained, opened up and cleaned. Without this requirement the owners would never think anything was wrong as long as it heated the building or water. (An old "Dead Man", before his passing told me, : "Kid, no one ever thinks the "local yokel" knows anything") So someone with a clipboard and who traveled maybe a 100 miles to get here is credible. This assures that the equipment gets some attention every one or two years.

As for the isolation valve for the expansion tank, I think is a good idea, especially with an old compression tank hanging from the ceiling.......But a steamfitter relative in Omaha told that the local code does not allow that valve on the tank. So it depends upon where you are and who is looking.