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Possible Leak in Residential Boiler

Mac_7 Member Posts: 14
This is a general question about a possible leak in our residential boiler.

We have an oil fired Slant Fin Liberty L-30-PT with tankless coil that was installed around 1994.  We just had the boiler's annual cleaning done, and the service technician thought there may be a leak in the boiler and suggested replacing it.  This, because he noticed fine red (rust colored) powder that had "puffed" out of the stack where it connects to the flue collar on the top of the boiler.  He didn't remove the front of the firebox, where it would have been easier to see an internal leaking problem.

There is no obvious visible water leaking from the boiler.  After he left, I took a flashlight and mirror and looked into the firebox through the observation port.  There is some white scaling under a lot of fine, dust like, rust powder especially on one side of the firebox near the tankless water heater area. There is crusted rust with small white staining on the cast boiler directly above where the flame shoots out.

Inside the firebox in general, has a fine covering of this rust colored powder, mostly on the side nearest the tankless water heater area, where about 1/8 inch of dry, rust colored debris looks like its running down that side of the firebox.  This fine powder does stick to a magnet.

The boiler doesn't seem to lose pressure because I've turned off the water feed to see if it reduces over a few days.  Over a couple days it has not. It doesn't appear to be leaking currently, but has apparently leaked in the recent past. I have not noticed any staining or water on the floor.

I've never noticed this red staining in the firebox before.  I do check the flame and cleanliness of the firebox throughout the year.  Is this a likely sign the boiler may intermittently leaking and need to be replaced?  Is rust colored dust normal inside a boiler's firebox?  I've tried taking a few pictures through the viewing port but they only will show very small areas.

I'm now considering calling in a different company to fully inspect this boiler to see if it actually needs replacement.

Any comments would be appreciated.  Thanks


  • STEVEusaPA
    STEVEusaPA Member Posts: 6,506
    I dont think it's leaking...

    You did 2 of the tests to check for leaks.  What did the flue pipe look like? Or the base of the chimney?

    Red powder, or rust in the stack is more of a sign of condensing in the flue way.

    You need an actual professional in there, to check your equipment, and your chimney.

    What were your combustion results from the annual cleaning, specifically the net stack temperature?

    When he did the cleaning, didnt he swing the front door open to expose the entire firing chamber (and clean it)?

    As someone who owns an oil company, I would be embarressed if I left you with the feeling that you need to constantly check your boiler.

    So yes, get someone else, preferably a recommendation from this site.  Where are you located?
  • Mac_7
    Mac_7 Member Posts: 14
    edited May 2012
    Possible Leak

    Thank you for your response.

    The flue pipe had a thin layer of black soot. Although, there were signs that water could have come down the chimney at some point because there was some rust stains coming from a joint.  This has galvanized steel pipe connections to a stainless steel chimney that goes up the center of the house, and has a good cap.

    The combustion results were as follows:

    Net Stack Temperature 400º

    Gross Stack Temp. 490º

    CO2 12%

    Breech Draft .04

    Smoke 0

    Efficiency 83 3/4%

    He only cleaned from the top.  Removed the stack connector piping, and stack collar, and brushed it out, and vacuumed from the top.  He also cleaned or replaced screens, replaced the nozzle, and replaced the oil tank filter canister.  But, when reattaching the stack collar, he smeared the connection with the top of the boiler with this hard chimney paste, rather than just bolt it down like usual.  Does that stuff chip off easily?  Don't know why he used that, since, to me it seemed to fit into the slots OK.

    He did not open the front of the firebox.  It has four bolts holding it on. Nor was access gained from through the flame tube.  Only once during an annual cleaning with this company with many different technicians over the years, was the interior of the firebox cleaned out.  And that was through the burner tube area that was removed.

    Since I've been investigating this condition, Ive learned a lot.  I do plan on having the boiler inspected, certainly through a different company, with the firebox cover removed.  If a licensed contractor is in this area, please PM me with contact info.

    I live in Plymouth, CT
  • icesailor
    icesailor Member Posts: 7,265
    Red Stuff:

    Here are two boilers. One is "Cold Start". It doesn't have a tankless heater like you do. The other set is a "Warm Start" boiler. Both are cleaned annually by myself.

    Notice the red crap. Notice that the COld Start is full of Kibbles and Bits. Notice that the Warm Start has no Kibbles And Bits but both have the red stuff. The warm start has a lot more red stuff. Red stuff is normal with red dyed fuel. I have a customer that uses ULS over the road diesel in his boilers. The ash in his boilers is light brown.
  • Mac_7
    Mac_7 Member Posts: 14
    edited May 2012
    That's the Stuff

    That's the stuff.  That red residue is what it looks like inside my boiler.  I was wondering if the red could be from the dye.  The technician was sure it came from a leak, but couldn't show me any evidence of a leak.  So, I've been looking for one ever since.  There is extra red residue going down one side in mine, which I still should make sure isn't rust from a leak.

    Now it looks like I need to have the cleaning completed since there is lots of red rubble in the bottom of the firebox.  All of what was brushed from the boiler fell to the bottom and it can be seen through the viewing port.  After this experience I will certainly be finding a new burner servicing company. This company is one of the largest in this area, and since I've been a customer for many years (18) I will be speaking with the owner of the company about this recent cleaning.

    I also wondered if that cement that turns rock hard that was used when he put the boiler cover/flue collar back on will allow it to be removed when the boiler needs cleaning again next year.  It was smeared thickly around the entire connection, even though the cover fit back into the slots without problem.

    I thank you icesailor for the comments and the pictures and also steve for your comments.  I will keep watching this boiler to be sure there are no leaks or other problems.  I certainly have learned a lot so far about my boiler.  I still will have another company to inspect it, just to be sure everything is functioning properly and there isn't some kind of leak.
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,506
    edited May 2012
    furnace cement.....

    It's ok that he used that, emphasis on "ok".  He shouldve used a gasket material to do it the right way.  If he didnt have any, he shouldve got some and came back.  The furnace cement will dry up hard, then probably crack. leaving you with a less then ideal seal, lowering your combustion numbers/efficiency, and lead to a little more sooting.

    There really is no excuse to not swing the door open every year and clean out the bottom of the boiler.  Even if it's not a swing open and just a plate, removing the oil line and 4 bolts should be a part of every cleaning, especially a boiler with summer/winter hookup.

    Bring that up when you talk to the owner.

    Edit:spelling mistakes.
  • Mac_7
    Mac_7 Member Posts: 14
    edited May 2012
    some pictures of the red stuff

    Thank you.  I was wondering if anyone would be able to chip that cement stuff off in a year or so.

    I've got a few (not very good) pictures that may show some of what I've been trying to describe.  The first is taken through the viewing port while the boiler is firing, so it's hard to really determine the color.  That red crusty stuff is what is coming down that one side of the boiler on the side where the tankless water heater is.  The other side of the firebox looks like the back... fairly clean.  The second picture is taken with a flashlight and mirror, mostly so the real color can be determined.  The red powder is also seen on the second photo just inside the viewing door, on top of the insulation.  It sticks to a magnet.  You can also see some of the white staining in the second photo also.

    Yes, I tried calling the owner of the company this morning.  He's gone for the weekend, so it will be next week when I bring my concerns to him.

    Edited to add details.
  • Mac_7
    Mac_7 Member Posts: 14
    edited May 2012
    firebox cleanout

    As a follow-up to this issue, I did talk to the owner of the company.  He stated they don't routinely clean out the firebox unless it's full.  And then, they don't like to take the bolted firebox plate off because it can be difficult to place back on without damage.  He said they can usually clean it out through the viewing port, or by removing the burner flame tube if it's necessary.

    Still not sure if this boiler needs replacing.  It still hasn't lost pressure for almost two weeks now with the feed water valve turned off.  The red powder is definitely rust because it globs onto a magnet, and it (the red powder) is still puffing slightly out around the stack connection when it starts up.  So, it's still blowing around in there.

    I'll be having someone else out to look at it for a second opinion.
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