Nightmare fuel, anyone?

Hap_Hazzard

It just dawned on me that maybe main vents with floats aren't such a good idea if, like me, you have an automatic water feeder on your boiler. Suppose that water feeder goes haywire and floods the boiler and the flooding continues on up into the mains. Wouldn't you rather have it leak out of your main vents than to proceed on upwards in search of an outlet?

And what if the radiator vents all have floats, and they all work. Would the water pressure just keep building until something blew apart? Would the boiler relief valve be the first thing to open, or might the pressure blow a radiator apart first?

Welcome to my nightmare.

Long Beach Ed

Float vents are notoriously poor at stopping flooding. We've had many haywire feeders and the float vents didn't stop the stream of water from reaching the ceiling.

Jamie Hall

Long Beach Ed said:

Float vents are notoriously poor at stopping flooding. We've had many haywire feeders and the float vents didn't stop the stream of water from reaching the ceiling.

That's encouraging. I think...

Hap_Hazzard

So the float can stop steam but not water, or does the bimetal strip exert more force than the buoyancy of the float?

Guess I need to do some testing.

ChrisJ

That's why I never understood why anyone was concerned about the Big Mouth not having a float. I constantly hear the floats don't really work.

JUGHNE

You could install an F&T spill trap on your boiler. Place it a few inches above your water line. Steam would keep it shut. Excess water out of the boiler would drain out thru the trap discharge piped to a floor drain...even install a wet floor alarm there.

Also a PRV ahead of the feeder would limit the pressure to the feeder components. The F&T may be limited in discharge flow rate.

Patent Pend BTW.....

JStar

I've done this once before. You integrate a high water control with the water feeder. You use the NC contacts (closed during low water condition) on a LWCO in series with the feeder circuit. Stick it right on a high tapping.

JUGHNE

But if your feeder was stuck mechanically or if you had an old school float operated leaky feeder or by pass valve leaked by .....powering down would not stop water adding.

JStar

Yup. You can install a extra solenoid valve. Or just hope it never happens.

ChrisJ

> @JUGHNE said:
> But if your feeder was stuck mechanically or if you had an old school float operated leaky feeder or by pass valve leaked by .....powering down would not stop water adding.

You could use another solenoid but that might get stuck open from never being used.

Best to do what I did and manual feed only.

Hap_Hazzard

ChrisJ said:

Best to do what I did and manual feed only.

Then I can have dry-firing nightmares!

Long Beach Ed

The floats do work in concept. If the thing fills with water, they'll usually seal the vent. The problem is that the water's often a mucky, surging mess that bobs the float on and off of its seat. Often, if the mains are flooded, the boiler's still running, boiling some water in its base. This causes the surging, and the float's pin moves around, causing water to bypass it. I suppose in some circumstances, the floats are effective, though in my experience, they are far less than perfect.

The thermostatic bimetal strip may or may not exert more pressure than the float - I don't know - but it exerts consistent pressure, at least until the temperature drops.

Hap_Hazzard

If the outcome is to flood my bedroom and living room, I'm sure they'll work flawlessly.

JUGHNE

Hap you could add a second LWCO probe device.
The existing probe that calls for water is also the one that locks the burner out....yes???
If that probe system fails then no lock out......no water added.
Most comm jobs require a 2nd LWCO, manual reset.

Hap_Hazzard

I'm not sure I follow. How does a second LWCO prevent flooding?

ChrisJ

> @Hap_Hazzard said:
> (Quote)
> Then I can have dry-firing nightmares!

Chances of lwco failing are much lower than auto feeder issues. Second lwco makes it even less.

Hap_Hazzard

Oh, I see. Trade dry-firing nightmares for freezing to death nightmares.

JStar

> @Hap_Hazzard said:
> I'm not sure I follow. How does a second LWCO prevent flooding?

Certain LWCOs have an alarm circuit that will close on a drop in water. If you use this circuit, you can interrupt a feeder signal when those contacts open during a condition of sensing water. So the water rises, hits the LWCO, the relay energizes, the contacts open and kill the signal.

JStar

A LWCO is just a water activated relay.

Jamie Hall

How about what happened to Cedric? The last relay in the controller welded on -- and none of the safeties (of which there are several) could shut it down. That's what emergency power switches are for...

ChrisJ

Oh boy.........

ChrisJ

> @Jamie Hall said:
> How about what happened to Cedric? The last relay in the controller welded on -- and none of the safeties (of which there are several) could shut it down. That's what emergency power switches are for...

The irony in this is you're very pro nuclear, yet say software is dangerous and yet you're the only regular on the forum that almost had a meltdown.

Jamie Hall

True. So true... Where's my horse and buggy? (in the barn, actually... )

JUGHNE

Don't tell Hap about frozen contacts and run-away burners, he'll probably move to Arizona.

Hap_Hazzard

I've decided to start sleeping in the boiler room, so if anything goes wrong it'll either wake me up or kill me in my sleep and I won't have to deal with the fallout. Besides, it's nice and warm down there.

coelcanth

this happened to me in my old Brooklyn apartment late one winter night..
i noticed my living room light fixture starting to drip water, which seemed like an odd place for a leak so far from the kitchen/bath.
went upstairs (that's the third floor now) to wake up the neighbor at 2AM, and he answered the door in his pjs and standing in a 1/2" of water.
this was one of those times being able to turn off the radiator supply valve came in handy !

retiredguy

Geeze, why all the dooms day scenarios. Yes, float switches and low water float controls and feeders like the McDonald Miller 47's and 51's fail once in a while and will occasionally stick open due to a down stream flow restriction but why all the fuss. Crap does happen, even on the best maintained pressure vessels and boiler systems. In the 40+ years that I serviced and installed these monsters, I saw a lot of the impossible happen and I learned something new almost every day. Some failures and accidents are impossible to prevent. The maximum pressure a boiler system should see is that of the steam safety valve or relief valve setting that is well below the pressure rating of any of the devices or piping on the system.

ChrisJ

Jamie Hall said:

True. So true... Where's my horse and buggy? (in the barn, actually... )

The more I think about this the more confused I am.

You're all for simplicity for the sake of reliability on a simple steam heating system and do not trust software. And yet, you're pro nuclear for power plants. Basically a steam system on steroids that cannot under any circumstances be shut completely off. And if it cannot cool it self the fuel doesn't care, it's still not shutting off. It just keeps going, and going. They dry fire like a boss!

And all of them are incredibly complicated with software involved.

1Matthias

Fun fact: If the steam mains are high enough, by the time the water hits them a pressuretrol set to 1.5 cut out will be off due to the water pressure. Ask me how I know this...

ChrisJ

1Matthias said:

Fun fact: If the steam mains are high enough, by the time the water hits them a pressuretrol set to 1.5 cut out will be off due to the water pressure. Ask me how I know this...

If the supply tappings are blocked by water I would expect that to happen before water leaves the boiler?

Canucker

> @ChrisJ said:
> (Quote)
> The more I think about this the more confused I am.
>
> You're all for simplicity for the sake of reliability on a simple steam heating system and do not trust software. And yet, you're pro nuclear for power plants. Basically a steam system on steroids that cannot under any circumstances be shut completely off. And if it cannot cool it self the fuel doesn't care, it's still not shutting off. It just keeps going, and going. They dry fire like a boss!
>
> And all of them are incredibly complicated with software involved.

It's also monitored 24/7 by highly trained teams. Can't really say that for the average residential/commercial steam boiler.

Jamie Hall

Actually, @ChrisJ , it's not that complicated. What I want and need for myself is one thing. What I see and desire to have happen for society and mankind is quite a different thing -- but that gets into some pretty heavy philosophy.

And for the comment on tappings and @1Matthias 's comment -- quite true. But in the case of what happened to Cedric, the relay in question was the one which connects the mains power to the burner motor -- the last step in the chain. And once its contacts had welded, the burner got power come what may, since all of Cedric's controls are in the 24 volt side to the burner control box, not in the mains power circuit.

Jamie Hall

I'll add a little bit here. First, on nuclear power. It is a technology, and no technology -- I can't think of a single one -- is inherently either bad or good. Conversely, what people do with the technology -- regardless of what the technology is -- can be either good or bad; bad, perhaps to the point of being genuinely evil.

What is tragic (and genuinely evil) is when men fear some thing or some one to the point where they fail to deal with it and just hide. That is what has happened with nuclear technology (it's also happened politically and socially, time and time again -- but that's another topic!). Looking around at the various small, tentative efforts which have been permitted by that fear, I am quite convinced that in the 70 years since the first commercial power reactors were turned on we -- the western world -- could have developed far safer nuclear reactors than we have (not that the ones we have aren't pretty safe) for half the cost and effort we have put into hiding fearfully in corners, and I know we could have developed safe and secure waste storage -- if not even possibly beneficial uses for the waste.

This is the real tragedy. We have, as a society, turned our backs on a technology which could have -- and could still -- provide power safely to the billions who don't have it, never mind those who do luxuriate in adequate power today. We could have done it without damming some of the great rivers of the world (Mekong, Yellow to name two) or flooding out native peoples (Muskrat Falls is the current poster child). We wouldn't have wind turbines in dubious places, or grid scale solar power on what should be productive farm land. We wouldn't have a truly serious problem with carbon dioxide emissions. And so on.

We have damned ourselves with our fear, and where we -- mankind -- go from here I do not know.

Homily for the Friday of Christmas Week. Sorry...

Hap_Hazzard

How many Fukushima/Chernobyl magnitude accidents would it take to convince you that the technology is inherently unsafe?

PMJ

Hap_Hazzard said:

How many Fukushima/Chernobyl magnitude accidents would it take to convince you that the technology is inherently unsafe?

The "technology" is not static. It evolves as it is worked on. So your question is unfair.

Anything installed now would be Generation IV which you should read about. Different universe on safety from the equipment in those accidents. Nuclear power will eventually be the choice as nothing else can compete on any level. Hopefully we won't end up being the only country that doesn't know how it works because we were too afraid to work on it. If you want something to worry about how about being the only country who doesn't have the best power technology. Now that would be dangerous!

ChrisJ

> @Hap_Hazzard said:
> How many Fukushima/Chernobyl magnitude accidents would it take to convince you that the technology is inherently unsafe?

Three Mile Island was almost on the first on that list.

Jamie Hall

Since I separate the fundamentals of the technology -- in this case, capturing the energy from nuclear fission -- from the application -- in both the cases you cite poor or obsolete implementation -- a lot. One could make the same fundamental argument about steam boilers -- a lot of people were killed by them, back in the day. Or automobiles. The automobile, parked in the driveway switched off is just a lump of metal (well, some of the newer ones seem to spontaneously combust, but...) but once it is out on the road, it is either a great benefit -- or a lethal hazard.

We often comment -- on a minor scale -- about this when folks ask what boiler to buy for their heating. And what we say is it really isn't the boiler, it's the installation. Same principle

One could look at it the other way 'round, if one chose: there is no technology which is inherently safe. The hazard, or lack of it, associated with any technology is completely within the control of those who implement it.

It is quite true that one can eliminate the hazard associated with a technology by simply refusing to use it. This is as true of a stone axe as it is of a nuclear reactor. But this is to deny one's self or others of the benefit of the technology, and that is just plain evil (and I do not use the word "evil" lightly). And that, too, is just as true of a stone axe as it is of a nuclear reactor.

And ultimately, in the end, the only thing that any of us really has to fear is that we have been, in some way, genuinely evil and have not repented.

BobC

Boiling water reactors are inherently unsafe, operating a nuclear reactor at high pressure is just asking for it. In the late 60's a liquid fueled reactor was operated at Oak Ridge labs. That reactor was shut down on Friday afternoon and restarted on Monday morning for 4 years and did so without major incident.

Because the fuel was in liquid form it could not melt down and the reactor ran at close to atmospheric pressures. It was safe by design and ther are versions that require no water for cooling so loss of water or cooling pumps is not an issue. These reactors can run hotter because you don't have to deal with water and steam becoming highly pressurized at high temperatures, they are inherently more efficient and produce much less nuclear waste. Solid fueled factors usually use pellets that are encased in zirconium, if that gets too hot it not only swells and jams reactor rods but it out-gasses hydrogen which is explosive, most serious nuclear accidents are mad much worse when the gass explodes.

Research on these liquid fueled reactors was stopped by the Nixon administration because he wanted to move the jobs to the west coast and the nuclear fuel industry had a lot to gain by keeping us on the solid fuel wagon.

We know how to build much safer and cheaper plants, we just don't have the willpower to do so. The world would be a much better place had we gfone to liquid fueled reactors in the 70's and 80's, Chernobyl and Fukushima would never have happened.

Bob

ChrisJ

Gentlemen,

I was not intending to start an argument over nuclear power.

My point was @Jamie Hall is ok with software controlling that type of boiler, but not a simple tiny boiler in his house. That's all.


@BobC I suppose that makes sense except that we're not the only country in the world developing it so why isn't anyone else doing it?

Hap_Hazzard

@Jamie Hall, Basically, you're arguing that nuclear power would be safe in a perfect world. We don't live in that world, unfortunately, and, if we did, we wouldn't need nuclear power.

Jamie Hall

On @ChrisJ 's comment on why I don't have (not don't like, don't have) software controlling Cedric. That one, at least, is simple: it's not needed. I have no problem with software controlling things, assuming, that is, that the underlying thing is designed as best it can be. I have a big problem with software controlling things when it's being used to compensate for more fundamental design problems (an example would be the 737 MAX's use of software to compensate for a significant problem with trim changes with rapid power application -- made worse by the software itself not being fail operational, and low time pilots being asked to fly something just a wee bit more complex than a Cessna 172).

And no, @Hap_Hazzard , we don't live in a perfect world. Our task is to take that imperfect world, and use it and make it as good as it can be, for "all creatures, great and small". And that means using all the tools that our minds have discovered, not to destroy or damage, but for the benefit of our world.