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  1. #1
    Stanley Chow's Avatar
    Stanley Chow Guest

    Default Trane XR90 missing vent??

    Do both vents need to be extended to the exterior? This is a Trane XR90 direct vent furnace. Yeah...the condensate drain is missing a trap.

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  2. #2
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    Default Re: Trane XR90 missing vent??

    forget the furnace--any more pics of that water heater venting?

    As always, refer to the listed instructions. Many CAT IV furnaces are 'allowed' to vent this way even though it is not recommended as it can depressurize the room, which btw has a backdrafting machine installed (water heater).

    Looks like insufficient vent rise and insufficiient clearance to combustibles for starters on the WH.

    Keep the fire in the fireplace.

  3. #3
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    Default Re: Trane XR90 missing vent??

    The combustion air intake on the furnace does NOT need to be extended to the exterior. It is a non-issue that gets plenty of discussion.


  4. #4
    Stanley Chow's Avatar
    Stanley Chow Guest

    Default Re: Trane XR90 missing vent??

    Rod....The furnace is located in a room in the basement, which typically has minimal combustion air supply. Although allowed, should I report that it would be an improvement to extend the air intake to the exterior? Also, how do I know which pipe is intake and which is exhaust?

    Bob....I've already noted the lack of a 12" vertical rise in the flue vent connector off the draft hood. As confirmation for myself....the 12" rise is taken from the TOP of the draft hood, not the top of the heater....right??

    Thanks guys.


  5. #5
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    Default Re: Trane XR90 missing vent??

    Quote Originally Posted by Stanley Chow View Post
    Rod....The furnace is located in a room in the basement, which typically has minimal combustion air supply. Although allowed, should I report that it would be an improvement to extend the air intake to the exterior? Also, how do I know which pipe is intake and which is exhaust?

    Bob....I've already noted the lack of a 12" vertical rise in the flue vent connector off the draft hood. As confirmation for myself....the 12" rise is taken from the TOP of the draft hood, not the top of the heater....right??

    Thanks guys.

    No doubt it would be better to extend the combustion intake to the outdoors but I'm not sure that is a call for HI, others should chime in here. It's a matter of what's best vs what is incorrect.

    Also code says you need 50 cubic feet of volume per 1,000 BTU, if the space falls short of that then it's all a moot point, it's gotta be extended.


  6. #6
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    Cool Re: Trane XR90 missing vent??

    Quote Originally Posted by Stanley Chow View Post
    Rod....The furnace is located in a room in the basement, which typically has minimal combustion air supply. Although allowed, should I report that it would be an improvement to extend the air intake to the exterior? Also, how do I know which pipe is intake and which is exhaust?

    Bob....I've already noted the lack of a 12" vertical rise in the flue vent connector off the draft hood. As confirmation for myself....the 12" rise is taken from the TOP of the draft hood, not the top of the heater....right??

    Thanks guys.
    You can draw combustion air from the CAZ only where there is sufficient MUA. Even then it is stupid and lazy. You are deliberately depressurizing the house, which will pull in more cold air which will trigger a call for heat thereby consuming more energy. Meanwhile, if you have any other combustion appliances it may tend to backdraft them.

    the exhaust is the one on the right vented all the way out. ;-). If you pull the panel, you'll see which one is connected to the exhaust blower. On Trane, the intake dumps cold air right into the collector box with the clear plastic view hole. BTW, the joint btw the vent pipe and appliance collar usually gets caulked but not cemented. The vent pipe needs to be supported per the mfr. or use the plumbing code as a default.

    The vent starts at the top of the draft hood--not the flue gas outlet of the appliance. The vent is not directly attached to the flue gas outlet with water heaters--they are deliberately de-coupled. Problem is, it works. A draft hood can allow spillage into the CAZ. That's what makes gas water heaters so dangerous.

    Stanley, what is going on with that combustible wall and chimney with this orphanned water heater? It should be relined or replaced with a power vented model out the side of the house.

    Keep the fire in the fireplace.

  7. #7
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    Default Re: Trane XR90 missing vent??

    Stanley,
    I'm a little surprised you had to ask which one was the exhaust vent. It's also an indication that maybe you need a little more training on inspecting HVAC systems. This is really HVAC inspecting 101. If you removed the front cover, it would be obvious which pipe went where, and you should be able to identify the components of the system.

    You should also have a basic knowledge of combustion venting requirements, especially the size and locations of fresh air intakes, and size of rooms where the units are installed (or getting their air from). I'm can't say I agree with Bob that it is stupid and lazy to have the combustion air come from the inside of the house, since many systems do not have the provisions to run a pipe to the outside (for combustion air).

    If there is sufficient combustion air available for BOTH units (HVAC and WH), then its not up to you to tell someone they need to change something.


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