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  1. #14
    Join Date
    May 2004
    Location
    Rapid City, SD
    Posts
    7,415
    Just curious, but if it's a 90% furnace, with both exhaust and intake being pulled from outside. If the exhaust froze up, how would the pressure switch make and let the next step come on?

    If it was a 80% or maybe (big maybe) a 90% pulling freshair from inside, I could see it happening... maybe.

    Just wondering, not doubting you at all.

  2. #15
    Join Date
    Feb 2004
    Location
    southern illinois
    Posts
    5,536
    even if it did make you would think roll-out or venter limit safety would trip......must of been natural draft..older unit or somethin'..?

  3. #16
    Join Date
    Apr 2004
    Posts
    7,680
    I didnt rerad anything about that case but unless it was vented incorrectlty or safties were bypassed or defeated somehow, it wouldnt have happened.

    As for the vent. You know its part of the system, I am sure the installers will discuss your options and together you and they can select a place where it is less obtrusive and safe. The more difficult you make this, the more likley you are to have a problem. There are limits to what you can do and I personally dont suggest testing the vent tables by adding a bunch of elbows or extending it under the deck.

    Find a closet and go through the roof.

  4. #17
    Join Date
    Feb 2005
    Posts
    655
    First off all those pressure switches are Vacume switches on condensing units that I have put in,and would stay in open position if exhaust were plugged.
    Unit will not operate. [Safety]
    Also rollout [Double safety]

  5. #18
    Join Date
    Jan 2005
    Location
    Massachusetts
    Posts
    514
    I understand the house was two years old. I have a friend who is a Captain on the Fire Dept and I guess there is alot of talking being done about direct venting. They said they just go by manufactuers specs at the moment but now snowfall amounts are going to become a bigger factor. All i could get was it was a natural gas hot air furnace vented out the side wall. I dont know if it was 80 or 90%

    From what I remember from the news story. The husband worked for the town and was out plowing snow. When he came home the whole family (wife & 3 kids) were found unconscios in the house. They were air lifted to Boston and put in a atmospheric chamber. One of the children died.

  6. #19
    Join Date
    Feb 2005
    Posts
    3
    Just giving an update: the furnace was successfully installed. After seeing the vent, I decided it should go on the back wall since it was pretty big. The installers said the best place would be where one of my basement windows was, so they boarded that up & put the vent through that. I'll paint it in the spring. I'm very happy with the vent placement - it's sort of behind a bush and thus is not really noticeable. Thanks to everyone for their replies.

    Just passing this along (since I had no idea): forced hot air gas furnaces are closed systems. There is a slight, but real possibility that the heater exchange can crack. If it does, carbon monoxide literally pours from the furnace, through the vents, and into your rooms; it can fairly quickly be a threatening situation. Both the installers and a plumber said that if you have a forced hot air furnace, you should *definitely* get one carbon monoxide detector for each floor. You all probably know this, but it was news to me! And I've had a forced hot air furnace for over 20 years with no CO2 detector!!

  7. #20
    Join Date
    Feb 2005
    Posts
    655
    The sugestion you have carbon monoxide detectors in your home is a great idea but I question your contractors statement that carbon monoxide will poor in if heat exchanger cracks.
    These new Condensing furnaces are designed so inducer fan is on downstream side of heat exchangers which will create suction on Both heat exchangers not pressure if a crack were to occur.

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