How dangerous is this high pressure?

Ahomeowner

Should I shut off the boiler until the boiler guy arrives? This is a single family home and an older boiler which hasn’t had a time-up in a few years (we were supposed to be out of this house by now.) I’m very worried but it’s cold outside and this supplies our hot water too. Thanks 

mattmia2

I'd turn it off, then go to a hardware store or home center, get a gauge that screws on hose thread for testing water pressure, connect it to a drain in the system, open the drain and see if the gauges agree. it could be a seized relief valve and water logged expansion tank or it could just be a bad gauge. once it cools and the pressure goes down, also pull the test lever on the relief valve before firing it again to make sure water comes out.

bburd

It's possible that the feedwater valve is leaking and over pressurizing the heating system, but if that gauge is correct the relief valve should have opened at 30 psi. A failed relief valve is very dangerous.

EdTheHeaterMan

When was the last time someone operated the relief valve? It is supposed to be done annually. You might want to get a 30 PSI relief valve while you are picking up that test gauge. When you operate the relief valve, you may find that is does not work. Then you will have a replacement all ready. You might want to read the word that I put a red box around. I believe they put that word there for a reason. But I might be wrong!

HVACNUT

Looks like a Burnham Jubilee. The only valve is probably the boiler drain. And that's probably seized.

Is there an expansion tank in the ceiling in need of draining?

Ahomeowner

Oh, I definitely read the word “DANGER!” That’s why I posted! I just don’t know what could happen and if I should shut the boiler off in the middle of a cold winter night lest it explode in my basement! I have never operated the relief valve. It’s possible that it was operated at the last tune-up although I don’t recall ever seeing it operated. I suppose I should learn how to do that and start doing so on a regular basis. We got in touch with the boiler guy and he’s coming tomorrow. He said it might be the relief valve or the gauge. Wouldn’t it be something else causing the high pressure, which is not being relieved by the relief valve?  He also said it might be a bad gauge, but the gauge has changed. The first pic was about a half hour before the first pic I posted, and the second pic was taken recently.

i have one of those gauges that you hook up to a hose bib to measure water pressure, although it is not here right now. We have well water so the house pressure never goes above 60 psi. I thought it funny that there is a reducing valve with a max pressure of 125 psi when the house pressure cannot ever go above 60 psi. I’m unsure where I would connect the guage. There is only one spot that I see and it is under one of the expansion tanks. There are two expansion tanks, one on each side of the hydronic heat loop. There are no expansion tanks on the domestic hot water. There is a threaded pipe on the hot side of the domestic hot water, but the pipe looks smaller than a hose bib, and also, I’m unsure of its function or even how to open it since it doesn’t seem to have a shut-off valve.  And yes, HVACNUT, you are correct, it is a Burnham Jubilee.  

WMno57

Ahomeowner said:

Should I shut off the boiler until the boiler guy arrives? This is a single family home and an older boiler which hasn’t had a time-up in a few years (we were supposed to be out of this house by now.)

Can I interest you in a car that hasn't had an oil change in a few years? I was supposed to be out of it by now.
I'm sorry you are in a crisis, but you chose to roll the dice on this, and it came up snake eyes.
How cold is it going to get tonight? Can you afford to put your family up in a hotel with the money you saved on deferred maintenance?
We may be able to walk you through how to drain your domestic water and hydronic systems. That might not be necessary depending on the weather forecast.

WMno57

Most of the time there is a single root cause.
This has the look of two failed components.
If the gauge is to be believed then:

1. Something failed which caused the over pressure (pres reduc valve, expansion tank, etc)
   
2. Pressure relief valve (important safety component) failed to do its job
   

But a knowledgeable qualified person needs to be on site. Guessing over the internet isn't a good fit here.
I recommend a night in a hotel.

EBEBRATT-Ed

Shut it off until someone determines the pressure in the boiler.

It could be a bad gauge or a bad relief valve.

tim smith

Turn it off, go get a hose bib test pressure gauge, put in on the hose bib connection under the small gray expansion tank on side of boiler and then open the hose bib a turn or so and see what your reading is. Not something to fool around with. Relief may be blocked up or stuck and not going relieve anytime soon or if lucky just a bad gauge. Need to find out now! Turning off most important right now. To keep heat going need gauge to verify pressure. You might also be able to be an emergency request into your gas utility to come by and check for safety. Although many won't touch water side of boiler.

delcrossv

That's your pressure relief, for your water side. 150 psi it's set as is way too high.

do you have another relief on the boiler?

HVACNUT

delcrossv said:

That's your pressure relief, for your water side. 150 psi it's set as is way too high. do you have another relief on the boiler?

It's a domestic relief valve and 150 psi is typical. 

Ahomeowner

delcrossv said:

That's your pressure relief, for your water side. 150 psi it's set as is way too high. do you have another relief on the boiler?

Thanks. Now that you told me, it makes sense. There is a pressure relief valve on the boiler. It did open one time many years ago. I don’t recall what the needed repair was, but I do recall lots of hot water pouring onto the floor! I think it was replaced after that.

delcrossv

HVACNUT said:

delcrossv said:

That's your pressure relief, for your water side. 150 psi it's set as is way too high.

do you have another relief on the boiler?

It's a domestic relief valve and 150 psi is typical. 

Even with Pex? OK!

EBEBRATT-Ed

You should shut this boiler off. It's probably a bad gauge but you should not take that chance.

Ahomeowner

Our boiler guy didn’t seem overly concerned when we reached him (after I made my first post here.)  But you guys had me so worried that we contacted him again and he still didn’t insist that we shut off the boiler. He said the worst that can happen is it could start to leak somewhere. He is a licensed HVAC contractor. To clarify, this is oil heat, not gas. His ideas about what could be wrong are similar to yours. He only differs in not insisting that we shut down the boiler.  My main reason for posting was a concern about the possible danger that this might pose, as we had not yet reached him and the pressure gauge does read “DANGER.”

EdTheHeaterMan

Your old cast iron boiler is rated to withstand 30 PSI max pressure. This means that it will actually hold 3 times that much pressure. But what if it fails and for some reason the high limit does not turn off the burner in the heater (that may also be very old like the gauge). and what if the relief valve does not open when it is supposed to.

Being in the trade, many of us have witnessed or have found in our local news paper a story about a boiler explosion. They are very rare but they do happen. So your gauge is saying that the relief valve is not working. Can you know for sure what is wrong? Is it the gauge or is it the relief valve? I would not stake my license or reputation on the gauge.

Now you can have something else fail on an old boiler. Stranger things have happened. And I met with a potential customer in Stone Harbor NJ. I wanted to offer them a complete rebuild of the heating system. 2 weeks later they called me because the boiler actually exploded in the garage and blew a 2" deep crater in the block wall across from the boiler, when the side that blew apart ripped thru the sheet metal cover and hit the garage wall. I could not believe it even when I saw it with my own eyes. It turns out that the relief valve did not work.

Now my lower cost rebuild of his old boiler was no longer an option. He needed a complete replacement boiler. Oh well!

It is apparent that your HVAC guy has not experienced this type of failure or he may not be so confident that you are safe.

Here are some facts about water explosions.
1. Dynamite increases in size by a factor of 900 to 1000 times it's original size
2. When water changes to steam it becomes 1700 times larger that the water it used to be.
3. Water will boil at 212°F at sea level if not in a sealed container (like a boiler or pressure cooker)
4. Water at 50 PSI will not boil until the temperature increases to almost 300°F.
5. If the boiler were to fail from hydraulic pressure at 250°F water temperature, then the pressure would instantly drop to zero PSI on a gauge.
6. At that lower pressure the water would instantly Flash into steam and become more that 1700 times larger than it was as water in the pressurized boiler ALL AT ONCE.
7. That is more powerful than a dynamite explosion of the same size as the water.
8. Your boiler may hold more that 20 gallons of water and the rest of the pipes in the system may hold another 10 to 20 gallons of water.
9. How big would a 30 gallon trash can full of Dynamite explosion be?

To give you an idea how powerful a water explosion could be watch the Myth Busters blow up a 50 gallon tank of water

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

Glad I'm nt living in your home tonight.

pecmsg

Ahomeowner said:

Our boiler guy didn’t seem overly concerned when we reached him (after I made my first post here.)  But you guys had me so worried that we contacted him again and he still didn’t insist that we shut off the boiler. He said the worst that can happen is it could start to leak somewhere. He is a licensed HVAC contractor. To clarify, this is oil heat, not gas. His ideas about what could be wrong are similar to yours. He only differs in not insisting that we shut down the boiler.  My main reason for posting was a concern about the possible danger that this might pose, as we had not yet reached him and the pressure gauge does read “DANGER.”

Time to find a different service provider!

Ahomeowner

He came first thing this morning and it’s fixed. Ed, I think I see what you’re saying. Two components failed at the same time, the expansion tank and the pressure relief valve. If only one more component had failed during this time, such as if the burner did not turn off when the high limit (180F) was reached, it could overheat to the point that the pressure would reach 3x 30psi, and then a catastrophic failure of the boiler would occur.  I don’t doubt that that is possible, as anything is possible. He advised me to keep an eye on it, as there is one more possibility having to do with the hot water coil. But we have a new pressure relief valve now, so at least it won’t be catastrophic.

mattmia2

Since the pressure dropped when it cooled it is probably just a waterlogged/failed expansion tank vs a leak in the coil in an indirect/tankless coil.

HVACNUT

I see 2, #30 Extrol tanks. Both pretty old. Is one just for decoration? 

Ahomeowner

HVACNUT said:

I see 2, #30 Extrol tanks. Both pretty old. Is one just for decoration? 

He said one is separated from the system by a check valve (he used a different name) so it’s essentially useless. He replaced the other expansion tank but not this one.

mattmia2

One looks like it is teed off a port on a flow check but as long as the valves are open they are still open to the system and can take and return water to accommodate expansion if they are both charged and have intact diaphragms. Is this something like a converted gravity hot water system that has large pipes and cast iron radiators so it has a lot of water volume?

Or currently gravity hot water since I don't see a circulator.

EdTheHeaterMan

mattmia2 said:

One looks like it is teed off a port on a flow check but as long as the valves are open they are still open to the system and can take and return water to accommodate expansion if they are both charged and have intact diaphragms. Is this something like a converted gravity hot water system that has large pipes and cast iron radiators so it has a lot of water volume?

Or currently gravity hot water since I don't see a circulator.

MUST HAVE CIRC PUMPS. or the flow check valve(s) would never open.

There was a tankless coil in use qt one time too