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Condensate from chimmney

FKLaneHS Member Posts: 8
Burnham ES-25 gas boiler installed 2 yrs. ago w/55 gal.water heater storage tank. 2 zones, outside reset,new ss liner inside clay chim.When outside temps get below 40's I start getting a light sheen of water down the wall.  Absolutely not weather related. Neighbor had same system put in same time by same plumbing company on Long Island  in NY. Has same exact problem. Burnham customer service absolutely worthless. Ditto National Grid, contractor. Was told I need to keep domestic hot water [email protected] deg. by the plumber. .This is an outside chim.  that was not insulated.  Water stain is a littl  rusty--seems the Stainless Steel liner that is code----was not exactly the best on the market. Magnet sticks. Anyway, put the flue damper switch in the always open position and problem cleared up.  Shouldn't there be another solution besides resorting to this.


  • JStar
    JStar Member Posts: 2,752

    What size is the liner? How tall is the chimney?
  • CMadatMe
    CMadatMe Member Posts: 3,086
    edited December 2012
    Drain Tee

    The ES2 is 85% AFUE and due to low stack temps (the reason for the liner)

    yes it is going to produce condensate. Could simply install a stainless

    drip tee to catch the condensate. Condensate is not a bad thing just needs

    to be properly removed. You may have to also install a condensate pump as well

    as a acid neutralizer as the PH of the condensate is around 3 and will

    eat away any cast or copper drains.

    You have also created a potential hazard by leaving that damper open as well

    as paying to keep a chimney warm.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • VictoriaEnergy
    VictoriaEnergy Member Posts: 126
    edited December 2012
    Stainless liners

    Stainless Steel is a very broad term that covers a wide range of differing steels where the base iron is mixed or alloyed, with other metals like Chromium, Nickel, molybdenum etc.

    Most stainless liners for oil or cat 1 gas appliances that are expected to be exposed to condensation for only short periods of time are made from "304".  A magnet will stick to 304, but with noticeably weaker attraction compared to ordinary steel.

    Example:  http://www.duravent.com/Product.aspx?hProduct=8 


    The companies that make the liners also have specalty liners made from more exotic (read expensive) alloys with much higher corrosion resistance like AL29-4C with vent components that have heat resistant seals in the joints and condensate drain tees for applications where continuous condensing or near condensing conditions are present. 

    Example:  http://www.duravent.com/Product.aspx?hProduct=13

    You'll see there are a few options between the cheapest 304 liners and the AL29-4C system, but only the AL29-4C is guaranteed to withstand continuous condensation.

    Keeping the damper open will stop the problem temporarily, but your liner is probably already toast if you're seeing a lot of rust, and you are seriously impairing the efficiency of your new boiler by doing so.  Isn't better efficiency what you wanted from the new boiler?
    Home Owners Please Note:

    You are receiving advice from some very skilled pros completely free of charge. One of the reasons I participate is to sharpen my own troubleshooting skills. So; did we get it right? I would be grateful if you extend this courtesy back by posting the final outcome of the issue you are inquiring about. Thanks
  • Jack
    Jack Member Posts: 1,046
    Insulated liner

    And insulated vent connector are always good on a re-line. At 85% you would expect some condensate on start-up, but the condensate should dry up as the system operates. Opening the damper is altering the dew-point temp in the stack and allowing the flue gases to stay as flue gases rather than falling below the dew point temp into water. Insulating the pipe from the boiler to the chimney cap should have the same affect by preserving the temp within the stack to keep it warm enough to vent.

    The condensate you are getting probably has a Ph of about 3.2. Limestone is one of the common products used to neutralize that Ph. Think mortar mix for your brick chimney and your concrete basement floor. Over time the condensate can "eat" your chimney. Won't happen today or tomorrow, but drip, drip, drip...a slow but insidious process. Insulate, as should have been done initially.
  • Bob Harper
    Bob Harper Member Posts: 969
    chimney liners

    Chimney liners must be listed to UL 1777, which is a bit misleading. This std. covers CAT I gas, oil and solid fuel applications. For CAT I gas, a liner may be listed even though it is aluminum or lower grade stainless steel, such as 304 or 304L. However, most pros use 316Ti now. The addition of molybdenum increases the corrosion resistance without sacrificing too much resistance to intergranular corrosion or the formation of chromium carbides at the boundaries at high heat. AL29-4c is 29% chromium and 4% moly, which does great against most but not all corrosion, such as from corn stoves but this alloy does poorly against high heat and is very difficult to machine and fabricate. You need to match the alloy to the fuel and class of service.

    Since the UL STP voted to soften the requirements for aluminum liners (against my vote), I personally think alum. liners should be banned for all but direct vent gas fireplace applications. It cannot even pass UL  2158a as a listed dryer  vent transition duct.

    The new polypropylene venting systems show great promise over illegal Sch40 PVC although some are being listed under UL 1738, which is really not a liner listing but for CAT IV gas rigid venting. Stay tuned.

    Regardless, the chimney should be inspected by a pro and repaired or upgraded as needed for the class of service.
  • FKLaneHS
    FKLaneHS Member Posts: 8
    condensate from chimmney

    From bottom of 90 to top of the cap is 25 ft.
  • FKLaneHS
    FKLaneHS Member Posts: 8

    Chimney guy said he can insulate between liner and chimney with vermiculite. He has done it many times before. Also said he can add tee at base. It will evaporate at base from heat passing. I converted  from oil to gas as the only way to get gas service to the house. Otherwise would cost $6000. to get gas service.  Oil burner was on its last legs so I went with what I could afford. Got rid of patched 275 oil tank(was smelling out the house) New gas burner,55 gal.storage tank, and new liner and 2 -7day programmable stats. Licensed plumber, inspected by National Grid, and $5500. It seems an insulated liner would have worked better.
  • FKLaneHS
    FKLaneHS Member Posts: 8

    I'm going to insulate and see if that helps. Neighbor had same exact problem and had entire liner removed. After 2 years in it was still in excellent condition(chimney guy did not want to be responsible for other peoples work) Insulated liner solved the problem. Also put in 6"tee but it does not drain to anything.
  • icesailor
    icesailor Member Posts: 7,265
    Insulated Chimneys

    In Massachusetts, a replacement gas appliance that vents into a three sided outside chimney may be illegal and the only vented into an insulated flue inside the three sided outside chimney. For the reason that you are experiencing. There is no way that you can send up enough heat to warm the chimney that is exposed to the outside. Even if the chimney is inside, if the exposed part that is 4 sided is too tall, it may not pass code.

    Continuing education is a beautiful thing. Just when some think they know it all, they find out that there is something more to learn.

    The only thing that will improve your situation is an insulated liner. Pouring vermiculite is a band-aid on an infection. The liner installer knows that or else he wouldn't be so quick to just shove a liner down the flue and collect the cash. Then suggest a band-aid as soon as there is a problem. How many times did he say he has done that?

    Add the additional cost of your chimney flue problems and a direct vent boiler isn't a really bad deal. And cheaper to run too.

  • FKLaneHS
    FKLaneHS Member Posts: 8
    edited December 2012

  • JStar
    JStar Member Posts: 2,752

    The liner only needs to be 5". What size was installed? Has a combustion analysis ever been done?
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