Pressuretrol and Pig Tail

EBEBRATT-Ed

glad you fixed it because that is an important safety control. I was more concerned with the safety aspect than the actual setting. If someone cranked the thermostat up and the pigtail to the control was plugged (as you found it) the boiler would build pressure with nothing to shut it down and you would be relying on the pressure relief valve to keep from blowing up!

As mentioned in the other posts you may want a vaporstat. The correct settings will be as low as possible to heat the building while limiting short cycling of the burner as much as possible.


ED

Greg_27

Pressuretrol and Pig Tail

Last night I came home to a cold house. I went down to the basement and after checking a few things, I noticed the mercury switch in the pressuretrol had tripped.

So against my better judgement after reading "We got steam heat", I turned up the pressure to get the boiler to fire.

My pressuretrol is turned the wrong way on the pig tail. I knew this last year after spending some time on the wall and this site. However, last year this never happened. does the pig tail uncurl more over time?

And, What's the best method to straighten this out? Should I clean it out too?

Hope everyone had a safe holiday!
Cheers,
-Greg

Brad White_164

Something

I picked up from George Lathier (aka "Firedragon") is that the pigtails should be mounted so that the "curl" edge is aligned front-to-back relative to the control. (You would have to look at the side of the controls to actually see the curl opening if that makes sense; looking face-on you just see the curl edge).

The reason is, when the pigtail heats, it uncurls and rolls to one side, tipping the mercury bulb prematurely or holding it on beyond desired pressure.

I never would have thought of that.

And as long as you are possibly rotating it, you might as well clean it out I suppose.

One suggestion, anyway.

Brad

Paul Fredricks_3

It's probably always been close to tripping and this time it just decided to. One of the great mysteries of life.

Big Ed_3

Not the problem.....

Your problem is a plugged pigtail. Clean or replace......

Unknown

Pigtail

Ed is probably right bur while you are going to have to take it apart to check it anyway, mount it on the pigtail so the face of the control is perpendicular to the orientation of the pigtail per the drawing below.

Glenn Stanton

Manager of Training

Burnham Hydronics

U.S. Boiler Co., Inc.

Unknown

Pigtail

> Your problem is a plugged pigtail. Clean or

> replace......



Ed is probably right bur while you are going to have to take it apart to check it anyway, mount it on the pigtail so the face of the control is perpendicular to the orientation of the pigtail per the drawing below.

Glenn Stanton

Manager of Training

Burnham Hydronics

U.S. Boiler Co., Inc.

Greg_27

Thanks guys. Is there anything in the pressuretrol mechanism that i'll need to clean? Or just the pigtail itself? -Greg

EBEBRATT-Ed

I would suggest taking the pressure control and pigtail off the boiler. Blow through the pigtail and the push a coat hanger or something into the boiler connection and flush everything out with water. Look inside the pressure control connection and you should see a small hole (maybe 1/8" dia) and make sure it is clean.

After reassembling it set the control so the burner will run and lower the setting so when the boiler builds steam it will shut the burner down (this is to test the control)If the control cycles the burner and the mecury switch moves in responce to steam pressure it should be ok. Then re adjust the control to the normal setting.

This is your safety high limit control and has to work correctly. If in doubt call in a professional and don't take chances.


ED

Greg_27

Thanks for the tip. Last night I went home and disassembled everything, and in fact the pig tail was completely blocked by a wad of some black, nasty goo. I finally got it to rinse clean. I reassembled everything (with the correct perpendicular orientation), cranked the pressure down to the original setting, and all is well.

I will definitely do as you suggested and lower the pressure further. How far down should I crank it? (See picture) Where it is set now it runs smoothly. should I put the differential down to the bottom?

Unknown

Greg,

You likely won`t be able to set this model of controller much lower, I have been able to get them down to 1.5psi max, but its tricky. At this setting I could get a 1psi differential, and thats about-it(as the adjusting screws are backed right-off),,, but you can try. Only a "vaporstat" will allow you to get into the lower(oz.) range. Edit-I also needed an accurate (low-scale)pressure-gauge to verify these #s.

Dave

Greg_27

Pig Tail Importance?

So, for those of you that followed this post previously, you are aware my pig tail was plugged. After I cleaned it out, I set the pressures pretty low.

It seems that there now is more even heating in all the radiators. Would an "almost plugged" pigtail cause uneven heat? or increase the pressure in the system?

Just curious to know your thoughts.

EBEBRATT-Ed

I don't think the pigtail being plugged would change the way the building heats. The purpose of the pigtail is that it will fill with steam on the first start-up and then steam will condense in the pigtail making a water seal or trap. This water seal stays there and keeps live steam from getting to the pressure control which some say it would shorten the controls life.

Paul Fredricks_3

Well...

With the pigtail plugged, or very close to being plugged, the steam pressure could rise to a higher point than normal be fore shutting the burner off. This would be the same as raising the pressuretrol setting higher, say 4 or 5 lbs. This would probably cause the steam to slow down and make it more sdifficult for it to get to the radiators. Once the pressuretrol did shut off, then the pressure would have a tough time getting back out of the pigtail, which is the situation you found originally.

Greg_27

Sounds like I may have increased my boilers efficiency this winter!

Dave_4

With the higher pressure this boiler was seeing, isn't there also a possibility that at times it was exceeding the operating pressure of the radiator vents, which would cause them to stay closed, cutting off steam flow and adding to the uneven heating problem?