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Failed steam boiler and chimney too small to vent


I have an 114 year old New England house that has a steam boiler with single pipe steam radiators which I bought a little over a year ago.  (Natural gas.)  The 30 year old steam boiler has rusted through and needs to be replaced. However, the chimney which it and the new gas water heater are venting to is too small and it is not fully lined - the chimney is partly split and could only be vented with a 3 inch vent - without insulation.  (Unfortunately I was not told about this problem when the house was inspected or when the boiler was serviced last year or when the gas water heater was replaced in this April or I would not have been doing this in the fall.) The chimney experts all agree I can't vent a new boiler in the chimney as it is too small. So that leaves me with several options. (Rebuilding the chimney is not possible right nowi).

the options seem to be:

1:  Install a class A external insulated chimney which would attach to the side of the house and the metal roof with brackets and install a new steam boiler (Burham Independence model or a Weil McClaine) and use the existing steam radiators.  The chimney would need a special piece to vent both the existing water heater and the new boiler.  The location of the chimney would be right over a walkway leading to the main door of the house and would be very visible.  The bracing would have some kind of angling behind it on roof to divert the snow. (My metal roof is really good at losing snow). As in nearly all options, the venting would have to be through a brick foundation and a secondary decorative stone wall foundation. I haven't been able to find a picture but I was told it would be shiny stainless steel.  Aside from looks, biggest concerns are snow coming off the roof and snow building up around the chimney itself. 

2. Install a steam boiler that can power vent out the side of the house either through a basement window. Meaning the window would have to be removed and covered over with pressure treated plywood which would be ugly. This contractor said I would have to remove my gas water heater because it can't be vented through chimney and install an electric one.  (City won't allow only water heater to vented this way).

3.  In talking with another heating specialist, I think I may have another power venting option of power venting a boiler out the foundation wall and power venting the existing water heater.  It sounds like this requires two different power venting locations as they can't vent near each other  (or the windows above the two basement windows).  I don't know if this saves money now but adds parts (fans or blowers that fail) that could be expensive to repair.

4. The last option would be install a high efficiency heating system that uses hot water baseboard. That would have an intergrated water heater as part of the system so only one hole would be needed to vent out and it would not be power vented so no mechanical power vents to fail. It would however require removing all of the steam radiators and black iron piping running all over the basement and replacing them with baseboard throughout the house. The steam pipes were insulated last year.  This would allow for multiple zones. it would however mean losing the radiators.

Some radiators are on inside walls, some on outside walls.  It appears that at some point some may have leaked as there is damaged wood where the pipes are.  However, I can't tell if they were fixed or if they stopped because of the leaking boiler (eg there really isnt much steam in them anymore)  There seems to be new parts on some of the them.  They did not bang or clang at all.  Aside from the themomstat being along the wall with the chimney was and therefore being a warmer location, the system did seem to work last year.  It would take about 30 minutes to get all of the radiators to turn on and sometimes the system would shut off before the heat reached the last radiators because living room would get warmer faster and the system would shut off.  I like having radiators but I have no idea how well they work (eg leak or not) if the boiler was working properly. 

What advise can you give?  What option would be best?

Thanks for your help!


  • SWEI
    SWEI Member Posts: 7,356
    Without seeing the house

    or at least having some drawings and a few photos, one other option comes to mind:

    Install a steam boiler that comes factory configured for power venting (Burnham Independence PV comes to mind, which works with 3” AL29-4C) plus an indirect water heater.  This will simplify the venting and may allow you to use the existing chimney.  It will also give you more hot water at better efficiency than most tank heaters.
  • ChrisJ
    ChrisJ Member Posts: 15,670

    Just wanted to chime in on this.  Last year I had a similar problem and it ended up the same price to tear the chimney down and have a B-vent installed in its location as it was to have an A-vent installed outside and leave the chimney abandoned.

    Have a look at the pictures in my signature.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    boiler repair

    in some situations, the boiler may be repaired, without the chimney arrangement being changed. this repair would include replacing the sections of the boiler. have the installer see if new sections are still available.--nbc
  • MyOldHouse
    MyOldHouse Member Posts: 3
    boiler has completely rusted out on the inside

    it is leaking and now has a very nice pile of rust under it....so sadly I am forced to replace it.  I believe we are also possibly getting carbon monocide through the chimney (someone tried to line it and couldn't get the liner down it so it is jammed up at the top part and is ripped).
  • MyOldHouse
    MyOldHouse Member Posts: 3
    this is what I wanted to do

     I do like what you did. I wanted to do this and if the plumber who serviced the boiler and installed the water heater earlier had caught the chimney problem, I would have had time this summer to do this option. I wasn't able to find anyone willing to do a full chimney replacement this fall and I got the sense that there are few here who do this and the cost is much higher than my other options.  My heating system is gone so I can't wait til next spring when someone is avaiable to replace the chimney.

    I am hoping someone will provide thoughts on the existing options I have been given so I can decide what is the best option. 
  • ChrisJ
    ChrisJ Member Posts: 15,670
    edited October 2012

    If I were you,  I would call around some more.

    While I realize chimney outfits may be getting a lot of calls now it took my guys two days to completely tear the 150 year old brick chimney down and install the B-vent.  ONE guy did 98% of the work, which to be honest in my opinion he was and is "the man".

    Remember this will be something you have to live with, it will be worth the extra time making calls. 

    Can you post some pictures of your boiler and its piping, as well as of many of the radiators?  It will help everyone give you a better answer on how to proceed.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • John Mills_5
    John Mills_5 Member Posts: 951
    save the WH?

    To save the water heater, can a metal liner be installed in the existing chimney for the water heater to vent in then get a power vent boiler?

    We are constantly taking a furnace out of the chimney in favor of a PVC vent 95% and then dropping a 3" or 4" liner in the chimney for the orphaned water heater. Codes are pretty lax around here though but that's following the National Fuel Gas Code.
  • ChrisJ
    ChrisJ Member Posts: 15,670

    Unfortunately this doesn't completely help him make a decision, there are no direct vented steam boilers.

    I believe he is trying to decide weather to convert the system to radiant heat (I hope if converting at all) or leave the steam system intact.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Bob Harper
    Bob Harper Member Posts: 1,034
    chimney vs vent?

    If this is Cat I gas then you don't need "class A" chimney--you can use the much cheaper B-vent.

    Chimney is required for oil and wood> venting for gas (unless you use type 'L' vent for oil)..  Confusing but a big difference.

    With regards to power vent options such as retro fitting the WH as a power vented model, you can do that only if it has been tested and listed for that application and the venting approved for positive vent pressure. You can NOT use any type of 'chimney', B-vent or L-vent for positive vent pressure applications.
  • John Mills_5
    John Mills_5 Member Posts: 951
    Burnham Independence PV

    It won't vent in PVC obviously but it is a steam boiler that will vent out a basement wall. 
  • Enreynolds
    Enreynolds Member Posts: 119
    Power burner

    You could also go with the Smith G-8DV with the Carlin EZ-Gas option for a wet base power burner option with up to an 85.6% AFUE.  Unfortunately, you apparently cannot have the DHW coil in steam trim.

This discussion has been closed.