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This past fall we had a new HVAC system put in along with new duct work and insulation. There were a lot of people in my attic, and over the course of the project, the collar that sits above my whole house fan was cracked in a few places.

Before the last guys left, I ran the fan and realized the fan was rubbing against the collar, making a horrific noise. They adjusted it and it was fine. Since that was the fall, we haven't actually had a chance to run it since. My attic will get upwards of 120 - 130 degrees in the summer, and I'm worried about how this collar will hold up in that heat.

I had the company over two days ago, and one of the guys put some duct tape (the shiny kind, not the standard gray) over the cracks to reinforce them. I told them it was fine for now but come summer, if things start moving around because of the heat and there's a problem, that I'll be expecting them to come back out and fix it. They complained about not being able to find that collar, about the unit being so old they couldn't replace it, etc. etc.

I'm wanting to know two things:

  • How would you expect a fix like their's to hold up in the heat? Am I worrying about this too much?
  • Are these types of collars able to replaced, contrary to their opinion?

There's hardly any clearance between the fan blades and this collar, so I'm worried that eventually the rubbing will start happening again, long after they've been paid. I'm trying to be reasonable and work with them, but I don't want to end up with a busted fan two years down the road.

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Here's what it looks like now:

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As cheesy as the tape looks, it will do ok, It is made to resist the temperatures that blow through the duct work. At worst it may fatigue over time, but I think it will remain intact. To be certain, later when it is running check it out up in the attic. If the plastic shroud that has the tape on it is jiggling, the tape may fatigue. Aluminum can't take a lot of movement.

The tech is possibly quite right in their remark about the part not being available.

If there about an 1/8" of room between the shroud and the blade, it will do well over time. Should it ever strike it, it will be in the near future, within weeks, if not sooner if it decides to touch again. Then the fix will be a heat gun to get the plastic to stay.

I really think that it will be fine. What I describe would be worst case scenarios

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As long as you stop bending it with your thumb it should be fine as a permanent fix. That aluminum tape doesn't dry-out & release like duct tape. Plus, that drop-on collar really isn't doing anything nor is it needed.

On the flip-side, plastic welding would work, but you won't get that tape off easily so forget that. You can cut-out the broken areas with tin snips or a Dremel in a U-shape. Or, even just cut-off that entire top bevel all the way around, which would give the collar more liberty to move around without interfering again.

  • That drop on collar is the shroud that concentrates the pull of the air coming through the fan. It acts the same as the shroud that helps keep the fan in your car from letting the engine overheat. Pretty important for the efficiency of the fan... – Jack Jan 18 '16 at 6:28
  • Come on Jack, you know it's just yuppie dressing to make the HVAC guys look good. I never had 1 growing up & that 1-horse puppy would blow you out of bed 2-floors away with your window cracked just a few inches. – Iggy Jan 18 '16 at 6:35
  • Are you talking about the 3 sided metal stack or the cracked plastic shroud the OP posted about? The 3 sided shroud is to keep the insulation from dropping through the blades or being stirred up by the fan. A little tall but if that is what they had on hand.... I never had one either, but my cousin had one, and I experienced it in the 1300 sq ft house, it had a nice breeze coming in. Nothing like what you suggest. – Jack Jan 18 '16 at 6:41
  • Just the useless black plastic shroud, that should've been centered tested & securely clipped down. Yeah, if all the windows were open then there was just a good breeze. But, close down the house to just a few bedroom windows & WOW. – Iggy Jan 18 '16 at 6:48

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