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  1. #16
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    Quote Originally Posted by Stustoys View Post
    10m of 200mm, Y into 3m 150mm on each branch
    17sqm and 14sqm(but we leave the doors open because for the most part we aren't really trying to heat those rooms), just getting heat to the other end of the house).

    Yes fire is plenty big enough, built into brick so has good heat store as well.
    Another reason for some insulation improvement and some automatic control. As we currently run the fan over night there must be some points when 90% of the heat it is moving is going into the roof.


    I was thinking about it sort of thing but didn't mention it. While I cant measure airflow I can measure pressure drop to that sort of level I believe*. Do I just need to measure the pressure difference across the fan(should be easy)or do I need to measure just inside the inlet and the outlet?(I don't have enough hose.... there cant be an real difference between the two aside from any leaks...right?)

    *just checked, can measure kPa to 0.01 which I guess will give me a number to work with but only just.

    It all looks ok. Will a pressure test pick up an internally collapse?


    You just want me to "walk" 15m through the trusted roof again don't you
    I think they are pretty "squished" over, and I don't think there is the length to do much about that. I'll go check when I finish this post. I have blue tape left from installing ducting on another place(I may even know where it is lol)


    Covered this in my last post.... don't you just love trying to deal with half the story, sorry about that.



    For sure. Perhaps I will start with just the one roll this, wrap it around the 200mm ducting and just see what I get from that.
    https://www.bunnings.com.au/earthwoo...ation_p0810985



    Well I dont want to make it to easy for you! hehe



    Placing a 90 bend(elbow) above the ceiling register.(perhaps not necessary given your last post)

    Back up into the roof I go.
    as your ducting should have been next size up at minimum, no need to measure pa as we know fan and duct are not matched. Yo aint going to get any better without changing it out.

    A visual inspection and feel will pick up a collapsed duct.

    A smoke test will tell if you have any air leaks but it will stink the house out...so best to just make sure all duct joints are taped properly...quicker as well ...so up in the roof you go if you havent allready done that .

    A s you say no need for that 90 bend...just tape it up if your concerned its a tad restrictive...doesnt look like it from you pic

  2. #17
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    Quote Originally Posted by eskimo View Post
    as we know fan and duct are not matched.
    We do?
    While you do, I sure don't.
    Are you saying because of the length of the run it would be normal practice to leave the fan at 200mm and go up a duct size?

    Quote Originally Posted by eskimo View Post
    ..so best to just make sure all duct joints are taped properly...quicker as well ...so up in the roof you go if you havent allready done that .
    Will do.

    SWMBO picked up a roll of insulation on the way home. Was up there this evening. Got the insulation rolled out over the trusts, just need to slide it under and tape it up tomorrow.

    Good time of year to be up in the roof.

  3. #18
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    Quote Originally Posted by Stustoys View Post
    We do?
    While you do, I sure don't.
    Are you saying because of the length of the run it would be normal practice to leave the fan at 200mm and go up a duct size?

    IMO yes..branch ducts should be 200 min.

  4. #19
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    It turns out what I thought would be the hard part, unrolling the insulation, getting it through the trusses and around the duct, was easy part. What I thought would be the easy part turned out to be pretty painful... taping it up. So while there is a fair overlap it currently only has a piece of tape across the joint every 450mm and the ends are tied closed with string! lol

    Turns out there is 12m of 200mm duct. So there is still that and the 150mm ducts without added insulation.

    The early results look better than expected. I'm getting about an 8C temp increase. With the same fan temp the outlet temp has gone from 33C to 41C. With an inlet temp of 17C that's a 50% increase in heat. Still losing about 19C. There is some wiggle room in those figures, took awhile to get a stable fire going this evening. I likely would have been happy with that, so would seem worth getting another roll and finishing it off.

    Quote Originally Posted by eskimo View Post
    IMO yes..branch ducts should be 200 min.
    Well expect some question if I ever get around to added another outlet. While I have you here, The ducting is run through the roof trusses(wood, 900mm centers), so sits near the bottom of the Vee between the king post and truss web(yes I had to look that up https://www.carpentry-pro-framer.com...roof-truss.png). Would it be worth using so blue tape to make a bit of a cradle? or am I over thinking things? lol

  5. #20
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    Quote Originally Posted by Stustoys View Post
    The early results look better than expected. I'm getting about an 8C temp increase. With the same fan temp the outlet temp has gone from 33C to 41C. With an inlet temp of 17C that's a 50% increase in heat. Still losing about 19C. There is some wiggle room in those figures, took awhile to get a stable fire going this evening. I likely would have been happy with that, so would seem worth getting another roll and finishing it off.
    When you're done there, feel free to head on over here and crawl under my house and do the same to my ducting. You'll be right, there's at least 12 inches of clearance on the high side....

  6. #21
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    Quote Originally Posted by Stustoys View Post

    Well expect some question if I ever get around to added another outlet. Would it be worth using so blue tape to make a bit of a cradle? or am I over thinking things? lol

    and if bends are not sharp your probably okay

  7. #22
    Join Date
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    Melbourne
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    Default Who Knew?

    Guy_With_A_Problem: Guys, I have a problem. My thing isn’t performing properly. I’m thinking about some cheap, amateur ways of bodging it up.
    Guy_Who_Knows_What_He’s_Talking _About: Yep, your thing is too small and not up to the correct spec. Get a bigger, better one.
    Guy_With_A_Problem: I’ve bodged it up proper.
    Guy_Who_Knows_What_He’s_Talking _About: Look out for problems.
    Guy_With_A_Problem: Couldn’t be happier, I’ve measured a tiny improvement.
    Guy_Who_Knows_What_He’s_Talking _About: OK.
    Guy_With_A_Problem: I’m a Legend!
    Everyone Else: Who knew this would happen?

  8. #23
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    Anyone seen a bridge missing its troll? I think I've found it.

  9. #24
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    Quote Originally Posted by Jekyll and Hyde View Post
    When you're done there, feel free to head on over here and crawl under my house and do the same to my ducting. You'll be right, there's at least 12 inches of clearance on the high side....
    No thanks, installed a system in a house like that, once in my lifetime is enough!

  10. #25
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    Quote Originally Posted by Stustoys View Post
    No thanks, installed a system in a house like that, once in my lifetime is enough!
    yep...stuff that ..i always got subbies to do it

  11. #26
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    Quote Originally Posted by eskimo View Post
    yep...stuff that ..i always got subbies to do it
    I worked with a guy that used to do installs. He told stories about houses so low you started at the "door" with a spade with the handle cut down and dug your way in from there. This would have been in the days of the aluminium ducting(no idea what it was called) so even more painful I assume than the springy stuff.

    Of course, maybe thats one of those stories that gets repeated.
    Last edited by Stustoys; 26th Jul 2020 at 11:12 PM. Reason: -went

  12. #27
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    [QUOTE=Stustoys;1972042]I worked with a guy that used to do installs. He told stories about houses so low you started at the "door" with a spade with the handle cut down and went dug your way in from there. This would have been in the days of the aluminium ducting(no idea what it was called) so even more painful I assume than the springy stuff.

    Of course, maybe thats one of those stories that gets repeated.[/QUOT

    Cant think of the correct name but I call it ductboard...
    A compressed insulation that has a outer liner of very heavy silver foil...similar to polystyrene board.

    But the main lenths were made up off site, and finer ducting alterstions and making of smaller stuff was done on site...usually in the the freekin hot ceiling space...

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