Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

scorched siding under boiler direct vent

Dave_61
Dave_61 Member Posts: 280
We have a direct vent gas boiler (Lochinvar EBN300) that is vented horizontally through our cedar siding. I have noticed over the past few years that the paint around the exhaust is blistering. I know the vent gets hot, but I thought I would remove the exhaust to see what is underneath. The siding and trim are charred and disintegrating. The exhaust pipe from the boiler is single wall FasNSeal. I found a part # FSVL 3605.

Where the exhaust exits the house, it goes through an outer thimble with fiberglass insulation as shown in the second picture. The insulation does go all the way around.

Inside the basement, the bay where the vent exits is covered in a galvanized metal shield which has a fair amount of corrosion. This whole setup is about 9 years old.

This does not at all seem right to me.

Check out the pictures. Without making a mess of the siding, etc as our fresh air intake looks the same and is mounted on the same sidewall, can I transition from the single wall FasNSeal to a double wall pipe just for that last couple of feet and put that double wall pipe through the existing thimble? Or is there a better/safer approach?

Thanks

Comments

  • kcopp
    kcopp Member Posts: 3,996
    Look at the....

    install directions... that is the oly way to know for sure. That being said, I don't think that fiberglass belongs there around any penetraition there shold be air space to let air move around to prevent hot spots. kpc
  • Dave_61
    Dave_61 Member Posts: 280
    Unfortunately,

    the directions in the I & O manual are very vague. They just say to follow all codes, etc. If you look at the second picture closely, that is a pipe within a pipe with insulation between the pipes. it looks like it was part of the exhaust kit. When I google the kit part number, I come up with nothing.

    I would just assume redoing this 2 feet of pipe and reusing the actual exhaust vent cap so it matches the intake which is outside the scope of the first picture..
  • Slimpickins
    Slimpickins Member Posts: 323
    scorched siding

    I believe the vent termination comes with a fire stop that fastens to the exterior. There's one for the interior as well that's just a flat piece with a circle for the vent. The exterior one has a lip around the edge that that termination rests in. It may be attached to the termination that you removed. You may be having combustion problems as well. If you never had it serviced I'd get a qualified service tech out to take a look at it.  He can check and make sure the heat exchanger isn't clogged and the gas manifold press. is correct and do a combustion analysis.  Good luck.
  • Dave_61
    Dave_61 Member Posts: 280
    We had it serviced

    last winter. Everything was fine. The termination has no fire stop. It just slides over the end of the exposed pipe. Should I just have any installer come look at this? This was done by someone who supposedly is a certified installer.

    It's been 9 years without a fire, but I am concerned this could be a fire safety issue looking at the charred siding.

    If you had to retrofit this, what steps would you take? As I said, the manufacturer of the vent pipe is ProTech (FasNSeal).
  • Slimpickins
    Slimpickins Member Posts: 323
    Research

    I think the termination is a Lochinvar part. Check online for a part breakdown or call Lochinvar tech support and they can point you in the right direction.



    Not sure how the FasNSeal connects to it, not sure if it's a mechanical connection or just siliconed.
  • Plumdog_2
    Plumdog_2 Member Posts: 873
    Vent terminus

    I think that vent terminus is wrong. It is better suited for the intake (combustion air) pipe. I have found a few like that that were not only scorching the siding, but were blasting CO back into the house thru the thimble. The cap is restrictive, and the seal (firestop) behind it is leaky or missing. Take away the insulation and let the firestop go uninstalled and you have a recipe for disaster. Get a proper terminus, and seal the penetration, and get it out away from combustibles. And sniff around near the boiler with an analyser to be sure the boiler is not leaking. The entire burner is under positive pressure and needs to have a good seal. 
  • Dave_61
    Dave_61 Member Posts: 280
    What would you

    recommend for a terminus (brand and part #)? The Lochinvar part actually says "hot" on it, so I assumed it was right for the application.
  • Dave_61
    Dave_61 Member Posts: 280
    Check out page 15....

    That is the exact terminus we have.

    http://www.lochinvar.com/_linefiles/EB-EW-I&S.pdf
  • Big Ed_4
    Big Ed_4 Member Posts: 1,897
    Manufacturer

    Call the manufacturer and see what they recommend . They may have changed their view on that type of termination ...
    I have enough experience to know , that I dont know it all
  • Dave_61
    Dave_61 Member Posts: 280
    Well...

    I spoke with the rep from Lochinvar, and he said that the pipe within pipe setup was fine (picture without vent termination), but that the termination should indeed be spaced away from house. he did not have any ideas on how to do that though.

    I'm wondering if there is anything I could purchase that would allow the termination to sit a little proud of the siding and still look good. Any ideas? Maybe one of those vinyl siding protectors that are sold separately? It has to somehow prevent water, etc from getting behind it too.
  • Big Ed_4
    Big Ed_4 Member Posts: 1,897
    Tee Termination

    I Like the stainless tee type termination used on some of the other units .. Wind blowing through a tee would not increase pressure on the exit of termination .... I am thinking the wind is blowing the acid base vapors against the inside siding ... I wonder what their feeling are ?
    I have enough experience to know , that I dont know it all
  • Patchogue Phil_2
    Patchogue Phil_2 Member Posts: 303
    maybe not scorched

    From just the picture #2,   that doesn't look "scorched" to me.  Looks more like water damage mixed with some oily residue from the exhaust.



    Rain and/or exhaust moisture could have gotten under the paint on the siding via the cut edges.  The vent grill trapped a lot of moisture,  it appears.  I'll bet when you remove the thimble you will see evidense of water getting inside the wall cavity.  Maybe some rot and mold.
  • Dave_61
    Dave_61 Member Posts: 280
    How about this idea?

    True. The galvanized metal shield inside is pretty rusty. But the cedar shingles do look charred. I was thinking of the following: use a heat proof silicone mat cutto size under the termination. Then use high temp silicone to caulk where inner tube goes through termination and also between silicone mat and siding as well as between silicone mat and termination.
  • Patchogue Phil_2
    Patchogue Phil_2 Member Posts: 303
    wood rot

    I've seen a lot of wood rot,  including on cedar.  And it often looks like charring.  Water and air on wood makes it black in color.  Ever see the underside of roof sheathing in an attic with a water leak?



    Granted I'm just going on what I see in a photo,  but it looks like water damage.



    If it *is* charring,  then the exhaust is way too hot.  A silicone shield is just a bandaid.
  • Dave_61
    Dave_61 Member Posts: 280
    I'll take a closer

    look. If it is rot, how would you recommend sealing it? I was thinking of sealing all 4 sides of termination with big temp silicone as well as sealing inner pipe to termination where it pokes inside.
  • Patchogue Phil_2
    Patchogue Phil_2 Member Posts: 303
    Dry it first

    The wood has to get dry first.



    If it were my place,  I'd investigate for any inner wall damage or mold.   Make repairs,  clean and kill the mold if necessary.



    If need be replace the shingle pieces that are damaged.  There are also epoxy fillers that can repair damaged rotted wood.  Scrape and sand the adjacent areas to the damage and bubbled paint.  Prime and paint including all cut edges.



    I would think about putting a small drip cap above the vent grill,  kinda like those above a window.  Stick it under the shingle above the grill.  Seal and caulk the thimble and also the grill.



    If you do not have any new shingles to replace the damage,  consider using a flat block to inlay,  cut a little larger than the damage area.  There are cellular pvc boards that accept paint or can stay bare.  Overlay the area with the 2-by material,  scribe a line.  Trim away the shingles,  caulk in place.  Cut a hole for the thimble to pass thru.  Caulk a plenty.
This discussion has been closed.