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direct vent wall heater exhaust options

freshby
freshby Member Posts: 1
edited February 22 in THE MAIN WALL
i want(need) to use flexible automotive exhaust pipe to vent the aforementioned heater(17,000btu). the heater is in a poured concrete basement. the exhaust needs to run up the concrete wall 7 feet, over the sill, and exit out the home 2 feet above grade, on the first floor. so, a total run of 8-9 feet. i intend to use the manufacturer's straight pipe (1.25" ID, give or take) for the first 4 feet or so, then join the flex hose to that. it is galvanized, not stainless. the manufacturer's rigid pipe is stainless steel.
just wondering what kind of temperatures to expect on the pipe, 5-6 feet above the unit. might there be potential condensation issues? and most importantly, exhaust leakage potential into the home, due to the corrugated flex pipe? does my plan sound feasible? the manufacturer sells "exhaust kits" and 90° elbows, but 1)the lengths are fixed and cannot be cut and 2)it is exorbitantly, rapingly expensive. also with my "flex plan", i wouldn't have to have anything near a 90° jog. i already have the heater and i already made the holes, just waiting on the pipe to be shipped...oh, and my plan meets the manufacturer's requirements as to number of 90° bends and total allowed vertical distance for my elevation.

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 15,350
    I can't imagine that your local fire marshal, building code enforcement person, or insurance company would be a bit happy with that arrangement. At least I hope not.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
    bucksnort
  • Drewser
    Drewser Member Posts: 34
    Having used that flexible galvanized exhaust pipe for temporary automotive repairs, I can tell you a few facts about it: 
    1) it does not last long with corrosive exhaust fumes and high temperatures. 
    2) it is not air-tight. It may be initially, but after several heating & cooling cycles the flexible spots loosen up and start to leak. 
    3) it’s going to get hot. Dang hot. Assuming that heater is 80-85% efficient, that flue pipe could be running 300-400°F. 

    Anyway. Having just installed a garage furnace in my shop, I am familiar with the type of vent pipe you mentioned that is crazy expensive. In my case, 7 feet of vent pipe, an elbow, and termination cost almost 2/3 the price of the furnace itself. It really stung to purchase and I looked at every other option. Straight through the roof, which isn’t an option for me, I could use the much cheaper B-vent, but it’s not allowed to be used horizontally here. The stuff I used is called Z-Vent, the gasketed stainless steel double-wall stuff. It’s expensive, but if it’s what’s called for, it’s what you gotta use. Don’t mess around when venting products of combustion, the risk isn’t worth it. 


    freshbybucksnort
  • GroundUp
    GroundUp Member Posts: 1,129
    Great way to risk CO poisoning and/or burn your house down. As was mentioned, the automotive flex is incredibly leaky and will get extremely hot. At the very least you will need a thimble for the wall penetration, but double wall vent pipe that's intended for this purpose is ideal. Z-flex is another option but will still need a thimble.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 8,519
    @freshby

    In a situation like that you have to follow the manufacturers instructions. The venting system is part of the heater and it was listed and tested as such. You have to purchase the vent material the mfg calls for

    If you have an issue the first thing the insurance company is going to look at is weather the MFG instructions were followed with the correct material.

    Your choice
    szwedjZman
  • Zman
    Zman Member Posts: 6,436
    edited February 22
    @freshby
    freshby said:

    I can't imagine that your local fire marshal, building code enforcement person, or insurance company would be a bit happy with that arrangement. At least I hope not.

    some reasons would be helpful. are you one of these people who joins help forums and answers every question with "you should hire a professional"?
    BTW, this is not that kind of site nor is Jamie that kind of participant.
    Your tone is a bit sharp on this one, take some time and read the previous posts. Unlike much of the internet, this is a place where people have polite conversations about all things heating.

    I agree with the above posts on this one. This is a matter of safety.

    What is the make and model of the appliance? Someone may have a better solution.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    freshbyErin Holohan Haskell
  • bucksnort
    bucksnort Member Posts: 32
    Go ahead. Just hope you don't have a fire or CO event. See what your insurance says then or just for shiets and giggles, ask them now about what you are planning on doing. Sure, it can be "cobbed" as you suggest. I wouldn't do it for anything until the right parts arrived and I had no heat. We don't "cob" things here. We do what's right.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 8,519
    @freshby

    With all due respect I have installed a few of those but it was years ago. Venting those (if it is similar to the ones I installed) is an issue

    As I remember it they are really designed to sit on the floor and vent it directly out the back with a straight pipe.

    They do make various venting kits and parts an pieces for "remote venting". As I recall they just slip together.

    I wasn't thrilled with the venting kit either they are expensive

    But in this case you have no choice.

    I strongly recommend you by what you need from Rinnai

    We can only tell you what we think is right.

    It's your choice what to do
  • HomerJSmith
    HomerJSmith Member Posts: 1,196
    DON'T DO IT. NO, NO, NO. They are not gas certified and they leak. I just install a Rinnai EX17CT(natural gas) like yours and I used Rinnai vent kits( I had to have two) from the manufacturer and I followed Rinnai's installation instructions to the letter. I got the kits from my wholesale distributor, however, you may be able to find what you need on Ebay for cheaper. Your installation instructions should have an accessory page showing the kits.
  • Jamie Hall
    Jamie Hall Member Posts: 15,350
    freshby said:

    I can't imagine that your local fire marshal, building code enforcement person, or insurance company would be a bit happy with that arrangement. At least I hope not.

    some reasons would be helpful. are you one of these people who joins help forums and answers every question with "you should hire a professional"?
    ;Nice insult, there, @freshby . You ask for reasons. The first one, and by far the simplest, is that such an installation would not conform to most building codes. I don't think you have earned any further effort on my part to respond.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • kcopp
    kcopp Member Posts: 3,660
    Yes those vent kits are expensive.
    Is it possible to build a secure shelf higher up on the wall to help w/ the vent length?
    Another option since its in a basement is to do one of the Rinnai FC824N
    FC Vent-Free Fan Convectors.
  • rick in Alaska
    rick in Alaska Member Posts: 1,160
    The Rinnai venting kits are designed for a particular balanced pressure in the system and adding any other components are going to throw that off. The air intake hose on the back is too long to easily fit behind it, but they do not allow you to shorten it for the reasons I just stated. Also, as others have said, it will void warranties and any fire insurance you have.
    Yes, the vent kits are grossly expensive, but you need to bite the bullet and use it. Maybe you could put the heater on a raised platform to make it fit.
    And you will not find a better person than Jamie, especially for any advice he has. Heed it!
    Rick
    JUGHNEHomerJSmithZman
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