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chimney condensate

Paul_69 Member Posts: 251
Will duravent stainless steel liner sweat in outside chimney? Used on weilmlain condensing gas burner


  • Tim McElwain
    Tim McElwain Member Posts: 4,628
    Which Weil McLain condensing gas unit are you referring to? The only condensing units from them have special venting requirements as do all condensing boilers.
  • Lance
    Lance Member Posts: 272
    All pipe and surfaces will condense water from vapor when the dew point is met. All chimneys will sweat when cold until they warm above the dew point. For the life of flues the question is how quick can we get above the due point to minimize condensation and re-evaporate remaining acidic moisture. Liners and additional insulation are the answer. The worst chimneys for condensation are usually exposed to outdoors on 3 or more sides, oversized, and have units making lower vent temperatures entering the flue. Condensation trouble is a result of us changing the original job of venting hot flue gases to cooler flue gases without adapting the chimney. A side effect of higher efficient heat units. The more resistant the flue liner the longer it will last. Its all in the engineering. Hope this helps.
    Ps. Beware the down draft conditions of the flue. Condensation could be a clue.
  • Paul_69
    Paul_69 Member Posts: 251
    Tim. Weilmclain 97 155. Inspector made us run duravent up a outside chimney instead of pvc
  • Bob Harper
    Bob Harper Member Posts: 1,044
    You need to tell us EXACTLY what model of Simpson DV venting you're referring to. It must be listed to UL 1738-period. This is a category IV condensing boiler that vents under positive flue gas pressure and is condensing even inside. Run outside other than a sidewall termination is really asking for trouble. Yes, this will sweat up a flood, which is why they incorporated a condensate drain in the appliance. Are you inferring this is a liner up inside a chimney or a 'vent'? If liner, again is it their polypropylene or stainless steel ?