Cause of dry firing considered

Heathapless

I do general contracting for a home with steam heat. Their new boiler failed after three months by dry firing and triggering a new smoke alarm system. The current working hypothesis is that sludge in the bottom of the boiler prevented the low water sensor from registering an empty boiler. Does this make sense?

BobC

Never skimmed?

For a 3 month old burner to have enough crap in in it to foul the LWCO I would think the system was never skimmed after the install. After installing a new boiler it has to be skimmed a few days after the install to remove any sediment caused by the installation and some times it has to be skimmed several times. I would ask the installer some very pointed questions.



This reinforces my habit of inspecting the boiler no less then every other day. The owner should contact the boiler manufacterer and scream bloody murder.



Bob

Jamie Hall

Somebody bungled...

but I wouldn't be too quick to blame the manufacturer or the installer; in fact, I suspect that a nice round of finger pointing will go on here.



A LWCO should be blown down regularly -- it should have been blown down at least three and as many as 12 times since that boiler was installed.  Even if the boiler was not properly cleaned (which it may not have been), that should have kept the LWCO functioning.  It's not a bad idea to check and see that it is, by blowing it down at least once in a while while the burner is running.  It should shut off.  That is usually the building maintenance person's (in a home, read homeowner) responsibility.



You don't mention an automatic water feeder.  Did the boiler have one?  If it did, is it connected to the LWCO (it should be)?  Does it work?  If not, why not?  I know some people have a some disagreement with automatic feeders, but the newer ones record how much water they are feeding so you can detect slow leaks.  And, in my humble opinion, if one is not installed one is asking an awful lot of the average homeowner (sorry, Joe Average, but...).



Does the boiler have a lower level, manual reset probe type LWCO?  (in my opinion, every boiler should... but...).  If so, what happened that it didn't shut the burner off as it should have?



Was anyone checking the sight glass, as Bob suggested?  Unless there was a fairly rapid loss of water -- that is, a leak -- that should have prompted someone to wonder why the water level was dropping long before the boiler dry fired.



Your working theory may be correct as to the ultimate cause.  However, you need to connect the dots and find out why the safety controls didn't do their job before assigning even partial responsibility for the problem.  Sorry about that.

Heathapless

The plot (or sludge) thickens

Thanks for your responses. The installer did a very good job on Monday replacing the boiler sections that had dry fired the day before. No discussion yet about the cost of the work. I am assuming it is under warranty, but we will see. I could use clarification on a few issues:



1)I was told that the LWCO was a probe-type and that it was covered with sludge which caused it to give a false reading that it was immersed in water. However, another source told me that these false readings are more common when surface foam gets on the probe. Given the location of the probe, that makes more sense to me. I have read that sludge plays more havoc with float-type LWCO. Sludge potentially puts the homeowner in the loop of responsibility, foam does not.



They installed a second float-type LWCO opposite the original probe-type (re-used, in fact). I am always in favor of redundancy.



2)Is there a sensor that feels the boiler overheating in the case of dry firing and can shut-off the gas supply?



3)They have the homeowners on a every other day half bucket bottom blow down....slap on the wrist or caution following costly warranty work?



4)I know that steam systems require more homeowner involvement, but I question the wisdom of putting older homeowners, who travel frequently and have little mechanical training in the critical role as the last line of defense before their new boiler melts down. That is not my idea of an intelligently-designed heating system.



Thanks.

will smith_4

New boiler dry firing

First of all, is the new boiler's near boiler piping correct? Is it per the manufacture's spec's? Make sure they haven't used only one tapping on the supply-if so, if they used the tap on the same side as the low water cut-off/ feeder, when the boiler fires, you can have a low water condition on the opposite side which the low water cut-off will never see, as the water level will tilt towards the LWCO. As per the thought that sludge can affect the LWCO-absolutely! If it's a float type and gets impacted with goo, the float won't drop properly to either bring in water or shut off the burner. If it's a probe type and gets encrusted with mineral deposits, it won't allow the burner to shut off either.

Gotta ask yourself-what killed the old boiler. Might have just been age. Might have been something external to the boiler. If I saw a section/boiler fail in only three months I would be looking outside the boiler.

BobC

Pictures?

Can you post some pictures of the boiler and the piping around it? Take

the pictures from a few different angles so we can see how it's piped.

It would be nice to catch any serious piping errors before they can

cause more problems. Also what make and model is the boiler and what is

it rated at in sq ft of steam?



Does the boiler have an automatic water feeder on it? If not, do we know

if the homeowner ever added water to the system and how often?



That second LWCO should insure fail safe operation as long as the boiler gets blown down on a regular schedule.







Bob

Jamie Hall

With regard to heathapless' Feb. 1 post...

I hope you all will excuse me if I say a word or two about the paragraph numbered 4.



First, the problem of poor maintenance and inattention is not confined to "older" homeowners.  I know a number of bright young homeowners who are very capable and conscientious.  I also know a number bright young homeowners who don't even know where the boiler is, never mind check it.  Ditto for older (a category into which I would place myself, by the way).



Second, any heating system requires a certain amount of attention -- and equally, any reasonably well maintained heating system will, barring catastrophic failures, withstand a month or two of total inattention.  Yes, one should blow down a float type LWCO more or less routinely, but it certainly doesn't have to be every other day (unless, possibly, one is adding a good deal of makeup water -- which suggests that there are other problems, eh?).  Yes, one should check the boiler water level by eye from time to time.  But one can leave a steam system to run itself for months, if need be, just as one can leave hot water or air.  That is, of course, in each case that the system itself has the proper checks and safety devices.  If it doesn't, all bets are off.



The worst damage (barring fire) I ever saw related to a heating system was from an hydronic system.  The homeowners, a reasonably intelligent young (thirties) couple had left the house unattended to go skiing for a week.  No problem there.  Unfortunately, not long after they left, the oil burner locked out (we never did find out why -- the damage was too extensive) and, of course, the house dropped below freezing.  A water pipe burst.  Unfortunately, the water pump was running just fine.  After considerable head scratching, the house was declared a total loss, together with all contents.



Is there a moral to the story?  Yes, stuff happens.  One can only do one's best to try to prevent it from happening, and we all have part of the responsibility for that.



There should, incidentally, be an overtemperature sensor near that boiler, which should shut it down in the event of a dry fire and complete failure of the fire box.  Along with the other safety controls.

Dave in QCA

LWCO and dry firing thoughts

Jamie, I agree with you.  And the time that a boiler needs the most attention is probably when it is brand new.  If it were mine, I'd be down their twice a day just to check things out.  But then, I'm not the normal home owner.  Normal homowners do not spend 4 hours a day on Heatinghelp.Com!  



This leads me to a thought that I have had for a while.  Given all of the safety devices that are required on boilers, it puzzles me why no manufacturer of a cast iron boiler offers a high temp shut down.  It could be any simple thermostatic device, hopefully with a manual reset, attached anywhere in the cast iron block.  It could be set for 230 F, well below the point when and damage is done, or the home is burned down.



Additional comment, in the winter time, whenever I am away, I alway have a neighbor check on the house.  If the weather is above 20, every other day, if colder, once a day.  Any system if capable of breaking down, and in the winter it does not take long for broken pipes to destroy a home.



I think there is a remote device, haven't seen much about it for a while.  But if measurable parameters were being broken, such as too cold, too hot, too noisy, etc, the device would call you on the phone and play a digital recording.  The messages were along the lines of "Brrrrrrr!  It sure is cold in here!"  

Jamie Hall

Robocallers...

Dave, there are indeed robocallers out there -- primarily sold in the agricultural markets (I see them at Teksupply.com, for instance).  They take a number of inputs -- ones typically which you might associate with agriculture! -- and call anywhere up to 8 telephone numbers with appropriate messages.  I know there are temperature sensors (too high, too low), water on the floor, open dampers, fan failure, etc. etc.



They aren't cheap, but for a big agriculture operation -- beef, horses, dairy, poultry -- they are almost mandatory.



No reason why they couldn't be adapted to a home or business perfectly well!



There are also sensors and base stations which allow you to interrogate all that stuff off the internet.  They really aren't cheap!



I like the idea of a boiler temperature sensor as a safety.  I do wonder why one isn't available?  Hmm...



Who spends four hours a day on the Wall?  ah... oh well!

BobC

Build one

It would not be rocket science to set up a temperature sensing chip on the surface of the boiler and use some circuitry to alert you to a potential problem. It would probably take about $20 worth of parts and some solder. You could use the output to trigger an alarm or trip a robocaller.



35 years ago i noticed a "hot smell" in the back hall of the apartment I was living in at that time. I went downstairs and found the landlords boiler with a cherry red spot on the side. I killed the power and cut the tank safety line to stop any more fuel from feeding into it just in case. That cost him a boiler but at least we saved the house from burning down.



Bob

Dave in QCA

I had something more "off the shelf" in mind

Such as a honeywell manual reset aqua stat with well.  It should thread into any unused port in the boiler.  Even though the well is intended to immersed in water, it would still pick up the temperature of a boiler block that was starting heat up from being dry.  If it was set at 230F on a boiler set for 2 psi or less, I cannot imagine any false trips.



Something such as this.  I am surprised that it is not mandatory, given that some codes require 2 pressuretrols, 2 gas valves, kill switch by the door, etc.

http://www.pexsupply.com/Honeywell-L4006E1067-High-Limit-Aquastat-130-270F-range-Manual-Reset-1707000-p

David Nadle

not great

Sounds like the installers offloaded some crucial work to the owners. Did the installers of the brand new boiler ever come back and skim? Not fair to blame the homeowners for that. I'd be pretty mad if my probe LWCO fouled due to installer negligence and was forced to accept an additional float LWCO (and the associated maintenance) due to their cover-your-**** move.

Draining half a bucket every other day will do nothing to prevent the lighter than water gunk from fouling both cutoffs this time.

BobC

Awful short capillary tube.

You could probably just lay that on top of a boiler casting and use a good thick bat of insulation (between the casting and jacket) to hold it in place. Problem is the capillary tube is very short. I wonder if they make one with a longer tube?



Maybe like the L4008 - http://customer.honeywell.com/honeywell/ProductInfo.aspx/L4008A1015



Bob

Heathapless

Some photos posted for comment

Thanks for your comments. I have watched Dan's video, as well as some others. I have included two pictures of the old boiler and several photos of the new one.



Even when I am not the GC for work at the house (as in this case) the owners invite me to be another set of eyes, hopefully with a bit more experience to draw upon. The installer is not inexpensive, is well-known in the area, and has a reputation for competent.steam work. Having made my share of mistakes, I am not out to blame or undermine the installer...just gather a few, more experienced , comments.



Most of the systems I have seen and read about show one or two risers coming off the top. In this install, the steam comes from the top right, and the header pitches down to allow the wet steam to return and the dry steam to rise. Is this set-up familiar to anyone?



The automatic water feeder shows 12 gallons added after one week of operation. I was told the feeder showed 300 gallons, after three months, prior to dry firing.



The owner is on a twice weekly (both sides) blow down schedule. The water is still quite dirty as can be seen from the gauge glass.



We had some short cycling of the burner caused by surging that was temporarily remedied by reducing gas to the boiler. The probe LWCO on the left was clicking on as soon as the burner fired but the house was not heating. Heat is comfortable now. Skimming is scheduled for this week.



The returns are nearly horizontal as they approach the boiler. With hindsight, I am sure we all wish the system had been flushed.



Thanks again.

Heathapless

Probe-type LWCO video.

I found this useful video which shows how the Hydrolevel CycleGard can be fooled by foaming on the surface of the boiler water and how it attempts to test around that condition. This is the probe-type LWCO used in our set up.



http://www.hydrolevel.com/pages/cyclegard.html

BobC

Great find!

That LWCO video was very interesting.



I think I'll implement an over temperature fault locking cutout on my boiler just in case.



Bob

Mark N

How much?

The boiler used 300 gallons in 3 months. Is the picture of the old boiler the one that lasted only 3 months or the boiler that was originally replaced? That boiler looks to be rotted out from to much feedwater. Has anybody figured out where the 300 gallons of water got to. My boiler uses only a few gallons a year.

Steve_175

A few Q's

What kind of system is this? Looks kind of like a down feed. See link.

http://www.bellgossett.com/literature/files/7250.pdf



As others have stated loosing that much water is a sign of a leak somewhere. That kind of water loss introduces a lot of fresh air and oxygenated water into the system which accelerates corrosion and all the muck you are having to flush out.

Are the rad vents hissing or spitting?

I would be willing to bet you do not have enough main venting either.

Heathapless

That is not a three month old boiler. Lucky for us.

The home was built in about 1925. I don't know that the corroded boiler in the picture was the original one, but it is possible. It is not the boiler that lasted three months.