Self Destructing Boiler... (ME)

[Deleted User]

we have LOT of these systems out there and this is the only one we've had this issue on. We're actually only 4,000 btuH oversized after you consider altitude and combustion efficiency. Th epump logic drops the circs out when discharge reaches 105F. Thats the Buderus way. If it were an issue, we'd have known long ago. Remember, this is the worlds OLDEST boiler maker.

ME

[Deleted User]

What would cause this??

My partner, Tom Olds, went to a job site yesterday that we commisioned in July of 04. Its a propane fired boiler doing radiant floor heating in high mass cementitious materials. The boiler has a factory logic on it that eliminates that possibility of long term condensation, so I feel I can safely say that what you're about to see is NOT condensation corrosion.

The brand name of the boiler is not relevant, and I'm sure that those who have worked on them before can identify the brand. It's NOT a manufacturer defect.

Take a look at these pictures and tell me what you think is causing this degradaiton. I have my ideas, but I want to pick your collective brains first.

I've also solicited the brains of the manufacturer to take a look and see if they can help in identifying what is causing this boiler to go away.

What say ye?

ME

John McArthur_2

Contaminants in the combustion air?

Anthony Menafro

Wet gas

Does the gas line come from the outside of the house(outside gas meter) causing the gas to condensate from cold to warm conditions?

Anthony Menafro

bob_50

Combustion air contamination

could be pool chemicals, beauty shop stuff, contact cement fumes, dry cleaning solvents. I've seen failures from all of the above.

Plumdog_2

could the flue gases be recycling into the combustion air?

S Ebels

Tough to say

without seeing the whole install piping included but possibilities include, low return temp causing condensation, combustion byproducts not venting, indoor chemical contaminants, a control failure allowing the afore mentioned condensation.......... Details man, details, give us the details of the complete job. What type of control was protecting the boiler?

Cosmo_3

need more pics

All the above guesses are my thoughts also, however where was the return temp sensor placed? I have been surprised in the past that this can make a difference, such as when placing sensors near closely spaced T's.


Cosmo Valavanis

Dependable P.H.C. Inc.

hr

More info about the \"logic\"

that prevents long term condensation. it sure looks like an issue caused by cold return temperatures and ice cold combustion air.

hot rod

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Cosmo_3

cold combustion air

Thanks for mentioning this Hot Rod. I have always thought that sealed combustion although great for protection from indoor contaminated air, etc can be all that good for the burners. What kind of long term experiances do you have? Most of the sealed combustion gas products I have installed admittedly do not have many problems.... so far. I have installed a lot of Weil Mclain gold GV boilers, now Crown CSC series, Vitodens, etc. So far I have not noticed this kind of corrosion in them, but I wonder what happens in colder climates where the incoming combustion air could be below freezing most of the winter?


Cosmo Valavanis

Dependable P.H.C. Inc.

S Ebels

Good point

The cold combustion air situation points out a big advantage for concentric type venting rather than two pipe. The exhaust pipe in the center can "temper" the incoming combustion air as it moves through the vent.

Guy_6

Outside air

Keep in mind that the air drawn from outside is not ALWAYS better: Recirc is a huge issue that plagues these situations, and not always from the appliance itself. Kitchen vents, dryer vents, heck, even moisture pouring off of a roof and "spraying" up in to the intake can give you headaches. I guess that you would have to think along the lines of "Would I want to sit here and breathe what my boiler is breathing".

[Deleted User]

More info....

OK, now that we've established that it is not a product specific problem, it's a 2 year old Buderus atmospheric, 160 K input dealing with a 110K load. It's using a 4 way mix valve with a Ecomatic Mix Card, and the onboard Ecomatic Pump logic set at 105 deg F. The reason I say it's not a condensation issue is because there is not a trail of rust running from the fire box over to the floor drain like we typically see in a condensation issue boiler.

The vent terminates on the roof. Not a gas recycling issue.

The combustion air is fine, not terminated near any other temrminations, or seeing dust etc.

There are NO hot tub or cleaning chemicals in the vicinity of the appliance nor the combustion air intake.

As for piping, it is in compliance with the manufacturers recommendations.

It is doing DHW through the prioritized 2107 logic.

It is on LP, and the two 1000 gallon tanks were recently buried (1 month ago) for aesthetic reasons.

Additional guesses please...

TIA

ME

hr

Something about the LP

and specfically the buried tanks has me wondering.

LP stored at ground temperature say 55°. Travels via copper through the cold air...??

hot rod

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Dale

condensation

I think that there's condensation on the castings. Perhaps from a shot dhw draw. Anyway, I would put a temp recorder on the outlet to make sure it didn't stay below 140F for too long.

Paul Rohrs_4

Calorific content of the LP fuel

any additives to the LP fuel? Is this additive decreasing the potential energy of LP. I know the Gas Co "juices-up" the nat gas content on occasion.

Regards,

PR

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Dirk Wright

Combustion analysis results?

What are the combustion analysis results? I would suspect moisture in the fuel, but I'm just an amatuer....

John McArthur_2

I too am suspect of the LP but would there not be other customers with similar problems? Poor quality gas would not be an isolated problem.

I can see very cold combustion air creating condensation. FWIW I had a job once that the intake air was ducted through a heated joist space to a fan-in-can. The duct condensated so badly that the HO thought there was a plumging leak. The two Burnham atmospherics are still humming along though. The job is about 8 years old now.

Brad White_9

My gut says

1. Condensation (visible in photograph? seems moist), but from too-short cycling; not enough burn-off time maybe? Given load to capacity ratio this may have merit, especially in that it is not "winter" yet. May be enough burn-off to forstall visible floor dripping which may hide that clue. Pull out your State-Reading HOBO's and see

2. On DWH, is the return blended with any other HWR? Or is the HWR from the domestic heater the first one back with no real mixing. (Again, thinking condensation).

3. Pitting to me points to chlorides although you noted none seem to be present. Looks nastier than just water meets iron. Were the buried tanks salvaged? Thinking they might have been used for something else such as halogen storage. A reach, sure, but that buried tank variable begs other questions.

4. Does the damage seem to be consistent across all sections or does it skip them now and then (hard to tell despite photo clarity). If so, what might be happening within those sections to lower the temperature?

5. A question really: Do you know how long this has been going on? Dumb-A-- question for why would you look if there was no problem? But just trying to assess if there is a timeline when variables such as the LP tank burial took place -versus the start of the corrosion of course.

6. Water make-up ever an issue? Pin-hole leak of treated boiler water? Another reach.. all that comes to mind for now.

leo g_13

Hmmm..

what comes to mind for me, is remembering one of your latest posts. The derating one. It appears that the boiler may be too big. So as others have said, to short a burn times.

Leo G

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Ed_26

boiler

Would there be a floor drain close by? Perhaps dry & venting sewer gas thru the boiler by natural draft up the chimney? Or.... floor drain used for water treatment drain?

S Ebels

All the LP issues aside

Such as firing rates and de-rating still should be adressed by the 2107 and pump logic. It should keep the condensation at or below maximum acceptable amount.

A combustion test would be valuable info to have whilst trying to cipher this on out.

[Deleted User]

BINGO!!!

Ed wins the Cupie Doll... I too suspect that the floor drain trap went dry and this is the byproducts of sewer gasses, laden with chlorides from the washing machine and dishwasher on the floor above being drawn into the combustion proccess.

I say this because the bucket of oxides that Tom brought back were relatively carbon free and relatively dry. Just BIG scaley chunks of rust that had accumulated int eh bottom of the combustion tray.

I supposed a person could try an do a chemcical analysis on the rust particles, but at what expense...

The only other time I have seen this side stream of oxides was from a water heater that was exposed to fluro carbons from laundry prespray materials.

Whoodathunk... Sewer gasses.

Thanks all, please continue to asses and diagnose. Unfortunately, no C/A was done because the tow analyzers we have were in different parts of the state. Not really sure that it would have shown anything anyway.

Thanks for the input.

ME

Paul Rohrs_4

Wow,

Sound like one more reason to sell condensing boilers, keep the traps primed.

Thanks for the lesson.

Regards,

PR

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jerry scharf_3

why not rule out the condensation

ME,

Speaking to the man with the HOBOs, why not set them up for fast poll and take a days worth of supply water, return water and vent temps (if the sensor can nadle it.) Then you can rule out the controls rather than guessing...

jerry

Keith M

have you thought about

the condensation happening in the summer.
Some people think they are drying their cool and damp basement during a nice hot summer day by opening doors and windows. If the boiler has intermittent pilot ignition the cast iron HX is the basement's ambient temperature and the HX could easily become a "condenser" while absorbing all of that latent heat.;-)
Check out a psychrometric chart, a quick check shows on an 80F day with 70% RH the dew point is around 68F. This is at sea level.
Just a thought, check it out.
Keith Muhlmeister

Keith M

have you thought about

the condensation happening in the summer.
Some people think they are drying their cool and damp basement during a nice hot summer day by opening doors and windows. If the boiler has intermittent pilot ignition the cast iron HX is the basement's ambient temperature and the HX could easily become a "condenser" while absorbing all of that latent heat contained in the water vapor in that hot humid air.
Check out a psychrometric chart, a quick check shows on an 80F day with 70% RH the dew point is around 68F. This is at sea level.
Just a thought, check it out.

Keith Muhlmeister

Mike T., Swampeast MO

Dare I suggest that proper sizing of the boiler may be the culprit? Perhaps the "factory logic" breaks down when the boiler isn't typically oversized and is driving a high mass, low-temp system.

Cosmo_3

son of a biscuit......

I feel like zuppy the pinhead... I had this exact thing happen to me years ago. Couldn't figure it out, then I noticed that I could hear the water rushing everytime the HO flushed the toilet. As a plumber I am a little embarrassed that I did not guess this right away!!!


Cosmo Valavanis

Dependable P.H.C. Inc.

[Deleted User]

Brad

In the same order asked...

1. It's not a condensate issue. Note the bottom of the fire tray. No signs of continuous condensation.

2. Yes, DHW is a dedicated circuit and prioritized pump. No blending necessary or possible due to DHW priority logic.

3. You and I agree on the chloride pitting. It is SEVERE. Although there are no chemicals in storage in the basement, they are used in the laundry and dishwashers whiich share a branch of the sewer, not on the same floor, bu tin the slab of the basement. Hence, when the clothes washer discharges, and th eboiler is running to satisfy the DHW load for said washer, and the floor drain trap is dry, boiler IS exposed to chlorine gas as the washing machine or dish washer drains.

4.Dame 1 photo shows the TOP of th heat exchanger, just under the flue gas collector. Dame 2 is of the fire box below the HXer, adn dame 3 is the bottom of the heat exchanger, just above the fire box. What condensate that appears in the picture is a consequence of hte plugged heat exchanger. The boiler WAS rolling out of the combustion chamber, but not in a position that would have caused the flame roll out fuse to go.

5. THere does appear to be some what of a corelation between burying the tanks, and the problem if having to hard reset the boiler, but I really don't think its a fuelish problem. NOt yet anyway. We commisioned the boiler 2 years ago and were called back recently because the consumer kept having to turn the power off and back on again to get it going. When he called us, he told my pard that the flames appeared to be bright white... now THAT got MY attention in a hurry.

6. We do not allow permenant make up connections to our boilers at our insurance companies request. Instead, we provide a reservoir tank to compensate for the loss of system volume during initial start up and deaeration. Once deaerated, system volume becomes stable, and if leak is developed in system, low water pressure cut off activates, shutting down the boiler before the LWCO gets a chance to activate. Worse case scenario, we lose 5 gallons of fluid, which WON'T cause a major catastrophic amount of damage.

THanks for the thoughts.

ME

[Deleted User]

The combustion air...

comes from two 6" vents with hooded screens on them. They;re NOWHERE near any other vent terminuses etc. just clean outside air.

ME

Mt. Falls Mikey

Not very scientific but...

Is this boiler in a cellar with stone construction,or an old coal bin area?? These enviroments kill boilers fast.

[Deleted User]

2 year old cement basement...

no dust of any sort. Family computer room right next to boiler room.

ME

Mike T., Swampeast MO

Just thinking off the top of my head without concern for who made.

Tom R.

Sewer

Mark, I can't believe that the HO was at a computer next to a room with a dry trap and didn't smell anything. Are you sure they aren't shutting the boiler off on weekends, if they go away?

Brad White_10

Once the sewer gas part became evident

it was so clear, Mark. The moisture just looked like condensation but not enough to drip in the pan. Good exercise in en-masse troubleshooting, wasn't it? Yes we agree the nasty pitting just HAD to be chlorides. Amazing what just traces in vapor can do! Wonder if a trap primer in the FD will be enough now? I would plug it and not take the chance.

I like the insurance companies idea of no direct fill. I am thinking of specifying Axiom feeders on my design jobs from now on.

Always learning. Glad you could share their misfortune with The Wall.

[Deleted User]

The solution....

Fill trap with fresh water. Pour a few teaspoons of 30 W motor oil into trap. Oil will not evaporate, nor mix with water and always floats on top of water. If floor drain gets heavily used, replenish oil seal.

Before everyone on a septic system jumps my case, I had a waste water treatment specialist tell me they would prefer we use MOTOR oil instead of VEGETABLE oil because veggy oil hydrolizes and makes it virtually impossible to seperate. Motor oil will always float on top of the surface.

ME

Brad White_9

Can you actually pour oil

in a sanitary fixture, Mark?

Here in Mass. we have a name for people who do that:
"The Defendant".

[Deleted User]

Laws vary from state to state...

Notice I said a few teaspoons, not a few barrels:-)

The second process after the raw sewage hits the treatment plant is oil/grease seperation. It's much more environmentally sane than one would expect.

I guess a person could use a trap primer, but that seems like SUCH a big waste of our most precious resource...

Robert Simplicio

Now I'm going to have to go and check my floor drains!!

I've got two I'm pretty sure are dry, and one is less than a foot from the combustion chamber of my 50 y/o boiler!

Cosmo_3

Try this instead

Jones STevens manufactures a product called "Trapguard". It is essentially a piece of rubber tube that curls up and seals against sewergas, but with only a couple drops of water opens up under the weight of the water. I was a little skeptical of them at first, and when you can't sell trap primers these are a good drop in solution.


Cosmo Valavanis

Dependable P.H.C. Inc.