What Causes High Pressure on Steam Boiler

nycpa

Hi, i have a Weil Mclain EG45 Steam boiler. Recently, I had the pigtail which was completely clogged cleaned out and I found out the honeywell pressuretrol doesn't work. I am replacing it this weekend and replacing the main vent with two gorton 2's. Have less than 30ft of main with 2 inch pipe. While the boiler was running, i noticed the 0 to 30 gauge PSI reader has hovering around 8 to 9. I turned off my boiler right after. What's causing the pressure to be so high and how can I fix this? Thanks

Dave0176

First has anyone done an EDR (load calculation of your radiators) to see if your boiler is oversized?? Second the pressuretrol controls boiler pressure, if yours isn't working I would not be running the boiler until it's replaced.

Dave0176

As far as the pigtail getting clogged, your boiler may need to be cleaned or even skimmed out.

nycpa

Boiler was put in in 1984, seemed to work fine until recently, how would I skim it out?

BobC

What was the pressure before you had the pigtail fixed? Do the air vents seem to be making more noise? With 8 or 9 psi they should be complaining loudly and could be damaged by the high pressure. Is the gauge on the end of what was a clogged pigtail? Do you know that gauge is working correctly?

If the pressuretrol isn't working the boiler is capable of making pressure until the 15 pound pressure relief valve pops IF the boiler EDR is much larger than the radiator total EDR. If you are in the cellar when that happens you will remember it for a long time!

Your gauge could be bad but I would keep the boiler off until you get a working pressuretrol to be safe.

Bob

nycpa

Before fixing the pigtails, I never seen the gauge ever move, now I see it going up slowly to 8 psi, the air vents aren't making that much noise other than the occasional hiss, how do I test to see if the gauge works, the gauge was not the end of the clogged pig tail

Fred

Did anything else change on the boiler or system? How long did the boiler run before the pressure got that high? Did you jack the thermostat way up and let the boiler run for an extended period of time? With a defective or out of adjustment Pressuretrol, the pressure will build if the boiler runs for extended periods. I'd get the pressuretrol fixed/replaced, set the cut-in at .5psi and the differential at 1psi and I'd put a 0 to 3 psi gauge on that same pigtail so you can see what is actually happening. Your 0-30psi gauge may be defective for all we know. If the boiler worked since 1984, without pressure problems, I wouldn't be to concerned about EDR.

BobC

You would have to put a known good gauge on the boiler and see what it reads. If the air vents are not making a lot of noise I suspect the gauge might be bad BUT I would get the pressuretrol working before running the boiler.

Out of curiosity what is the pressuretrol set to work at and why do you think it is bad? If you remove the pressuretrol and turn it upside down, look into the brass fitting and make sure the little hole at the bottom isn't blocked. If that pigtail was blocked it's possible the pressuretrol is blocked also.

Bob

Dave0176

Fred said:

Did anything else change on the boiler or system? How long did the boiler run before the pressure got that high? Did you jack the thermostat way up and let the boiler run for an extended period of time? With a defective or out of adjustment Pressuretrol, the pressure will build if the boiler runs for extended periods. I'd get the pressuretrol fixed/replaced, set the cut-in at .5psi and the differential at 1psi and I'd put a 0 to 3 psi gauge on that same pigtail so you can see what is actually happening. Your 0-30psi gauge may be defective for all we know. If the boiler worked since 1984, without pressure problems, I wouldn't be to concerned about EDR.

Yes a lot more has been explained now.

nycpa

The pressure from was set at 1differential and 2.5, it did stay on for a while before reaching the high psi, plumber said the spring was bad on it, wouldn't reset

williambarbjr

I have a Columbia steam boiler which has the following problems - start last year with overfilling & banging - replaced the LWCO and feed, did not help. Then went to every radiator and replaced every steam vent (only cause a couple of vents to drip. Noticed that the gauge read over 3 1/2 psi - pressure trol was set at .5 with diff of 1, replaced with new one (pigtail clear), went bad today because drip at one of steam vents, pressure up to 5 psi. Boiler is located in retirement home with many rooms ( all of which are extremely hot so manager has all but turned radiators off), the thermostat is located in a large open room on first floor (always calling for heat). Basically replaced all controls. What is causing the psi to be so much than pressure trol (why does it shut down boiler). The boiler has been operating for years under these conditions. I've already spoke to manager the install another heat source in room with T-stat. I'm at a lose as to why these problems have just started and what is the remedy.

JUGHNE

Your steam main vents may have been over pressurized if dripping water onto the pressure control??
Pictures of controls and main vents would help.

thermodyneboiler

A boiler is called a high-pressure boiler when it operates with a steam pressure above 80 bars. The high-pressure boilers are widely used for power generation in thermal power plants.
In a high-pressure boiler, if the feed-water pressure increases, the saturation temperature of water rises and the latent heat of vaporization decreases. The feed water can be heated to saturation of temperature in the economizer with the help of waste heat. Recovery from the exhaust gases is escaping to the chimney. Then the boiler supplies only latent heat of vaporization and superheat. Thus, a boiler operation at high pressure will require less heat addition for steam generation.

Sailah

In our steam heat world we consider over 75 PSIG high pressure. Power plant stuff is an entire other realm.

ChrisJ

Sailah said:

In our steam heat world we consider over 75 PSIG high pressure. Power plant stuff is an entire other realm.

80 bar is 1160 PSI.
That's scary.

ratio

If you think that's scary, Google "super critical steam".

Abracadabra

thermodyneboiler said:

A boiler is called a high-pressure boiler when it operates with a steam pressure above 80 bars. The high-pressure boilers are widely used for power generation in thermal power plants.
In a high-pressure boiler, if the feed-water pressure increases, the saturation temperature of water rises and the latent heat of vaporization decreases. The feed water can be heated to saturation of temperature in the economizer with the help of waste heat. Recovery from the exhaust gases is escaping to the chimney. Then the boiler supplies only latent heat of vaporization and superheat. Thus, a boiler operation at high pressure will require less heat addition for steam generation.

Obviously spam

https://www.youtube.com/watch?v=anwy2MPT5RE

Paul48

My father use to talk about 10000 psi off a reactor.

BobC

And that is why a pressurized water reactor is nothing but a bomb looking for somewhere to explode. Much safer to use a liquid metal fueled reactor that operates at room pressure - no boom.

Bob

ColinFarquhar

To keep things a little more in line... here in North America a heating/low pressure boiler is 15psi or less, over 15PSI is considered high pressure/power boiler territory. Conveniently lines up with ASME for Power Boilers or Heating Boilers (Section i or Section IV).

LORDHUMUNGUS1981

in my sisters building we had A new Super come along,My sister Lives On The fifth Floor,she s had These Holes In her ceiling,so The super Lights Up The boiler,it s been Holy Hell Ever since,Yesterday,I Went Down In The boiler room,Looked At Honeywell Pressuretrol Gauge,It s At 78,Now theres a New super

Ying

nycpa said:

Hi, i have a Weil Mclain EG45 Steam boiler. Recently, I had the pigtail which was completely clogged cleaned out and I found out the honeywell pressuretrol doesn't work. I am replacing it this weekend and replacing the main vent with two gorton 2's. Have less than 30ft of main with 2 inch pipe. While the boiler was running, i noticed the 0 to 30 gauge PSI reader has hovering around 8 to 9. I turned off my boiler right after. What's causing the pressure to be so high and how can I fix this? Thanks

@nycpa Will you mind updating what happened after you switch out the pressuretrol?

I'm having the same problem, replaced the clogged pigtail last week and pressure still climbing to like 10. Want to make sure that changing the pressuretrol will solve the problem or maybe it is just the gauge reading wrong.

Jamie Hall

@Ying -- it would be better to start a new thread... that said, there are a number of possibilities, ranging from a faulty pressuretrol (not that likely) to a miswired pressuretrol to a clog where the pigtail goes into the boiler to ...

Ying

@Jamie Hall lol, I did. Just looking to do more research on the topic.

I believe you responded on that thread a few days ago.

Was looking to do what you suggested on a low pressure psi gauge and put it on the pigtail, but none of the hardware store around me seems to stock them. Are you able to post a link to an online store that I can buy from or maybe to name of the part so I can search for it on supply house or amazon.

Also you mention throwing an elbow on it, does the low psi gauge need to be up right or can it be installed vertically.

As for the wires in the pressuretrol (Honeywell substantive 1PSI to 8PSI), there are only 2 wires. Red wire connected to the R screw on top and grey wire on B screw on bottom). Is this not correct?