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Will it last? A peak inside my Slantfin Liberty II

Took the smoke pipe off for an inspection of the boiler sections. I notice some red spots on around the nipples (and maybe a few are missing?). Is this normal? Something to be concerned about?

I need to make a decision on installing a replacement oil tank on this boiler --- originally installed by the previous owner in 2005 (brand new and well maintained, he said). Or replacing and converting to a gas boiler (we have for gas hw and cooking). Ideally I would install a replacement oil tank and hope to get another 5+ years out of this system.

No sign of leaks on the floor around the boiler. Haven't needed to add water so far this season --- had a loss of approx 1/8 - 1/4 in the sight glass since flushing and refilling two weeks ago. Appreciate any input.



    HVACNUT Member Posts: 5,026
    It's not terrible.
    Do you get it serviced annually with smoke and combustion tests?
    Rather than a new gas boiler, have you looked into a gas conversion burner to replace the oil burner?
    Jolly Bodger
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,132
    I thought think you’re fine too. I of course would stick with oil.
    If you’re investing in a new oil tank, you’d get nearly the same efficiency with a modern oil boiler.
    If you want to switch to gas, use the money for the new tank and either do what @HVACNUT said, or get a new gas boiler.
    Jolly Bodger
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 5,632
    edited November 2019
    RED = oxidation of the cast iron. This is happening as a result of condensation of flue gasses. For the first few seconds of combustion the water vapor of the byproducts of combustion condense on the cast iron. Within a short time (seconds in most systems) the flue gasses heat up enough to re-vaporize (evaporate) the condensation but the oxidation has already happened leaving a microscopic red (rust) stain. After several thousand start up cycles over the many seasons, you would get a little "red in the face" too.

    This is one of the reason for annual maintenance along with carbon buildup, and other stuff like scale., oil filter build up, electrode settings, safety checks, and 12 or more other things.

    The reason I mention this is ... the RUST is not from a leak in the boiler. It is just normal operation!
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    HVACNUT Member Posts: 5,026
    > @STEVEusaPA said:
    > I thought think you’re fine too. I of course would stick with oil.
    I should have started with that same statement. I don't know what I was thinking.
  • ethicalpaul
    ethicalpaul Member Posts: 4,668
    If I had gas already in the house and a bad oil tank, that tank would be gone yesterday
    1 pipe Peerless 63-03L in Cedar Grove, NJ, coal > oil > NG
  • Leorobt64
    Leorobt64 Member Posts: 8
    Thanks everyone for your input.

    I had planned for a gas conversion when we purchased the place and neglected the boiler as a result. Performed only minimal maintenance for two seasons -- never fully drained / flushed, never properly vacuumed/cleaned/serviced, no combustion tests.

    The gas replacement would require upgrading the undersized (3/4 in) gas line and installing a chimney liner. I also looked into a gas injector. The cost was close to 2/3rd the cost of a replacement gas boiler and unclear if there would be big gains in efficiency. That said, I'm curious to know the efficiency of the existing oil system after 15 years.

    As the current boiler works well to keep us warm and we've had minimal problems so far, I'm inclined to keep it for a few more years. Beginning this year, we will be gone between Jan-March. We will partly winterize the house and run the tstat at 50-55 degrees during that time, so I'm hoping our oil bill will be much lower.

    So now, I'm planning to maintain this system properly going forward and keeping my fingers crossed that my past neglect hasn't hurt the boiler.

  • Steamhead
    Steamhead Member Posts: 15,991
    Looks normal to me as well. That boiler is very well made, and should last a long time if properly cared for. S/F's current Intrepid model uses basically the same cast-iron block.

    These boilers run nicely with Carlin EZ-Gas or Midco EC burners, though the Carlins can resonate under the wrong circumstances. Here's a video of one we installed from scratch with an EZ-Gas:


    The advantage of a power-driven burner in a wet-base boiler like yours is that there is more available heat-transfer surface, and better control of combustion air. This results in more heat being sent into the system and less heat radiated into the basement or sent up the chimney.

    If it were mine, I'd put a gas burner in it- also I'd add baffles in the vertical flue passages if they're not already there. These would further reduce stack temperature.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • Leorobt64
    Leorobt64 Member Posts: 8
    Great video, thanks. Something to reconsider.
    Was that a new boiler, or a conversion/refit on an oil boiler?
  • Leorobt64
    Leorobt64 Member Posts: 8
    Oh, sorry, I see you said it was installed from scratch with the gas burner.
  • Leorobt64
    Leorobt64 Member Posts: 8
    I just found the efficiency ratings for this boiler. The LD-30 has an AFUE of 84%? That's better than I expected. Do these numbers hold up after 15 years?

  • Keith M
    Keith M Member Posts: 78
    Slant/Fin oil-fired boilers can be converted to gas-fired. However, please make sure your chimney is suitable for gas-fired and also the chimney must be cleaned. The boiler should be cleaned as well.
    The boiler efficiency should be the same as new provided it is cleaned. Any soot, rust or other material build up on the boiler's heat exchanger will decrease efficiency.
    If you convert to gas, please make sure the contractor has and uses a combustion analyzer to set-up the burner.
    Keith Muhlmeister
    Slant/Fin Corporation
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,132
    Also, switch to double acting baro and spill switch.
    EBEBRATT-Ed Member Posts: 13,440
    The boiler looks good to me. If maintained and serviced age has little to do with the boilers efficiency as @Steamhead mentioned above