Freaking Out Over High Pressure in One Pipe Steam System

Rob_40

Started up the gas atmospheric boiler, cold, as we are having a first cold night of the season. Two story house, eight radiators in all, with two main circuits. After it fires up, I watch some tissue paper I placed on the two main vents to see when they blow off. After 10 plus minutes, both vents are cold. I look at the boiler and am surprised to see the pressure gauge reads 30 PSI and the needle is still moving up. I check the vents, and lightly tap them with a hammer. Nothing seems to happen. I check the boiler, and the pressure gauge is pegged at what might be 40 or more psi (gauge's highest number is 30). Maybe I am noticing for the first time something that has happened all the time, but the highest I have ever seen it when I was paying attention, was maybe 15 psi. I shut off the emergency switch and waited a half hour. Gauge still pegged. I lower the thermostat and turn on the electricity, and the now the pressure has lowered to just above 30 psi. The pressure is slowly falling. Half hour later it is 27 psi. Pressuretrol is set at 2 psi and .5 differential. What is going on? I am leaving the thermostat all the way down. Not too happy about a cold night, but I cant stay up and watch it all night either.

mattmia2

Pictures of the boiler and piping, especially the relief valve. It should have opened before it got to that pressure. Is there a king valve on the outlet of the boiler that is closed? Even with no venting it is unlikely to be able to make that much pressure in the whole system unless the boiler is massively oversized.

Don't run it until you figure it out. If it is a residential boiler the relief valve should blow off at 15 psi(that in itself can be very dangerous, a room full of steam can burn lots of things including the inside of your lungs). It is time to call a professional that knows steam well

Rob_40

Here is a picture just after the burner was installed. The pressure relief is rated at 15 psi. No sign that it discharged. Pressure this morning is about 5 PSI.

https://us.v-cdn.net/5021738/uploads/posts/14488/New boiler 006.jpg

Jamie Hall

It is not clear if this is the first time this boiler has been fired or the first time this season.

Whatever, it is quite clear that for some reason or other your two (or, I hope, more) primary lines of safety didn't function. The pressure relief valve should have opened at 15 psi. The pressuretrol, if there is only one, should have shut off the burner at 2 or 2.5 psi, depending on the type.

Neither thing happened. That boiler is, in the present state, completely unsafe.

Unless you yourself are really good at trouble shooting, I'd leave it off until you can get a pro. in there. That said, however, there are a couple of things you can look at

First, the pressure relief valve. What is it rated for? There should be a tag on it which gives the pressure at which it opens. What does that say? Then check the piping to it. Is there any possibility that it is plugged, or that there is a closed valve on it -- or even (we've seen it) that there is a cap or plug on the outlet?

Second, since your pressure gauge seems to have moved, it's probably OK, though since it has apparently been overpressured it will need to be replaced.

Third, what is the water level on the sight glass? Is it correct?

But anyway -- shut off the emergency switch. Pull the fuse (or open the circuit breaker and put tape over it). And call a pro.

ChrisJ

If it was mine I'd be inspecting the gauge.
Was the piping to the boiler still cold? Any heat in any piping or radiators?

Do all of the radiators have vents and are all of the valves open?

You said it's still reading 5 PSI or so, is the boiler cool?

Rob_40

pressure relief rated at 15 psi, no sign it opened. Water is level is halfway between min and max. This is a boiler I've had for about 10 years. First start up for the season. So boiler started from room temperature.

Rob_40

ChrisJ: near pipes are slightly warmer than room temperature. No radiators have any warmth. Tested the lever on the pressure relief, and no discharge. Gauge still reads about 4 psi. Opened skim valve, a little dribble but no steam. Gauge still at 4 psi. So, the gauge seems faulty.

JUGHNE

My first guess would be that your gauge is junk.
If your system went into a slight vacuum on the last shut down, it could have pulled the needle down under zero.
There usually is a stop peg to prevent that.

So the needle may be just flying in the wind.

Most steamers that size would not get much pressure, if any up, in 10 minutes from a cold start.
Were the risers warm at all?

Could you post a picture of the gauge?

Jamie Hall

Have to admit that I suspect the gauge, too -- and as I noted, if it wasn't before and was telling the truth, it's junk now anyway.

But I would surely want to check everything else...

pecmsg

Got a pic from the front?

Rob_40

View of the front

https://us.v-cdn.net/5021738/uploads/posts/14486/New boiler 003.jpg

Rob_40

view of the gauge

https://us.v-cdn.net/5021738/uploads/editor/cn/zzl02xzd0kra.jpg

Rob_40

Gauge after ten minutes from restarting boiler:

dopey27177

After the gauge is changed drain out all the dirty water from the boiler. Flush the boiler until water is clean.

Jake

Rob_40

Any advice on a replacement gauge? Is an "internal syphon" gauge something special?

delcrossv

Rob_40 said:

Any advice on a replacement gauge? Is an "internal syphon" gauge something special?

Just means the pigtail is built in. (and, as the passages are small, more likely to get filled with crud)

If it were me, I'd replace it with a standard gauge and pigtail set up. Use a cross with plugs for the bottom connection instead of an elbow. From the boiler: nipple, cross, nipple, shutoff cock, pigtail , gauge.

ChrisJ

delcrossv said:

Rob_40 said:

Any advice on a replacement gauge? Is an "internal syphon" gauge something special?

Just means the pigtail is built in. (and, as the passages are small, more likely to get filled with crud)

If it were me, I'd replace it with a standard gauge and pigtail set up. Use a cross with plugs for the bottom connection instead of an elbow. From the boiler: nipple, cross, nipple, shutoff cock, pigtail , gauge.

Yeah,

Internal siphon aka useless gauge that clogs fast but gets the boiler out the door.

STEAM DOCTOR

Hard to tell from pics. Is relief valve piping flush against the cinderblock or is there an air gap under that piping? Gauge is almost certainly useless. 

Rob_40

There is about six inches between floor and bottom of discharge pipe.

EBEBRATT-Ed

Pick up a 0-30 pressure gauge with a garden hose female fitting and stick it on the drain port on the boiler. Clean out the drain by flushing first.

Rob_40

Gauge replaced, and pressure barely registers on the 30 PSI dial. So, I can sleep with heat without worries that the house will explode. Anyone recommend a 3, 4 or 5 PSI gauge? Thanks for everyone's insight.

EBEBRATT-Ed

@Rob_40

You can find gauges at Amazon or Supply House.com. Big box likely won't have a 5psi gauge. Winters is one brand that I guess is ok.

Dan_NJ

I had to order a WIKA 1-3 PSI direct from WIKA, could not find the one I wanted anywhere else.

delcrossv

Supply House has a 0-5 psi Winters gauge for around $25. Putting one in today, so I'll report back.

EBEBRATT-Ed

WIKA=$$$

Rob_40

Wika is all metric, which strains my already overtaxed brain.

AdmiralYoda

Friendly reminder.....by code you are required to have a 30psi gauge. So if you want a 3 or 5 psi gauge, use a Tee and install both a 3/5psi and a 30psi gauge. Just in case something happens....your covered.

I used a 5psi gauge alone for years and the pros here gave me the advice on the 30psi.

delcrossv

Here's what I just did. Little wonky, but I didn't want to risk cracking a 60 year old pigtail. 
My system pressure is so low, I'm switching to an ounces gauge. 

JohnNY

This is my installation from about 10 years ago. Just saying.

ChrisJ

delcrossv said:

Here's what I just did. Little wonky, but I didn't want to risk cracking a 60 year old pigtail. 
My system pressure is so low, I'm switching to an ounces gauge. 

Ounces is crazy talk.

mattmia2

Is there a valve between the boiler and the pressuretrol?

KC_Jones

ChrisJ said:

delcrossv said:

Here's what I just did. Little wonky, but I didn't want to risk cracking a 60 year old pigtail. 
My system pressure is so low, I'm switching to an ounces gauge. 

Ounces is crazy talk.

I have a 15 ounce gauge and that's too much. When I have a few bucks burning a hole in my pocket I'm getting something with a lower scale.

EBEBRATT-Ed

That is my concern also, looks that way maybe there is something behind the Ptrol we can't see

delcrossv

mattmia2 said:

Is there a valve between the boiler and the pressuretrol?

You referring to me? Yes, but I know it has to be open at all times. There's a set screw to lock it (in case of idiots). Guess the inspector didn't have a problem with it when it went in.

ChrisJ

KC_Jones said:

ChrisJ said:

delcrossv said:

Here's what I just did. Little wonky, but I didn't want to risk cracking a 60 year old pigtail. 
My system pressure is so low, I'm switching to an ounces gauge. 

Ounces is crazy talk.

I have a 15 ounce gauge and that's too much. When I have a few bucks burning a hole in my pocket I'm getting something with a lower scale.

I'm running a 2" WC gauge without a pig tail, just an 18" tall air trap and it runs about half scale most of the time.

PC7060

JohnNY said:

This is my installation from about 10 years ago. Just saying.

Man, that’s a small world!

ChrisJ

@JohnNY what pipe dope did you use back then that looked dark grey or black?

It blended in with the pipe nicely

pecmsg

JohnNY said:

This is my installation from about 10 years ago. Just saying.

Then it’s still covered by Warranty!

JohnNY

ChrisJ said:

@JohnNY what pipe dope did you use back then that looked dark grey or black?

It blended in with the pipe nicely

Typically wick and Hercules Pro-Dope.

ChrisJ

JohnNY said:

@JohnNY what pipe dope did you use back then that looked dark grey or black?

It blended in with the pipe nicely

Typically wick and Hercules Pro-Dope.

So you're a pro dope user?   

Rob_40

delcrossv said:

Rob_40 said:

Any advice on a replacement gauge? Is an "internal syphon" gauge something special?

Just means the pigtail is built in. (and, as the passages are small, more likely to get filled with crud)

If it were me, I'd replace it with a standard gauge and pigtail set up. Use a cross with plugs for the bottom connection instead of an elbow. From the boiler: nipple, cross, nipple, shutoff cock, pigtail , gauge.

Why the cross fitting instead of an elbow, or maybe a T fitting? Does it serve as a cleanout?