The Freshening Part 1

This week I have embarked on the final house project of the winter season: adding an ERV to my house. For those of you unfamiliar, an ERV is kind of like an exhaust fan for stale inside air, but it also brings in an equal amount of fresh air and exchanges the heat and humidity between them so you don't waste all your energy by venting nicely conditioned air into the great outdoors.

To start this off, I'm going to do a little prep work before the main event happens a little later this month, starting with making some ductwork accessories. To make those, of course, I'm going to need some sheet metal.

I originally intended to just get a 4ft by 4ft sheet, as I'd managed to lay out everything to fit, but I figured I'd rather not make two trips just in case I messed up, and I'll have another use for the rest later, so I went 4x8.

And by "lay out everything to fit", I really mean "to fit".

So let's get these parts cut out, which starts by getting the sheet marked up. I've tried a number of products that are supposed to mark well on sheet metal, but so far they've all failed miserably. Instead of all that rot, I'm going to scribe the marks using a utility knife.

First, though, I figure out where to scribe it.

Holding a steel ruler down with these welding magnets works surprisingly well.

Then comes the scribing.

This leaves a surprisingly visible and very accurate mark, and as a bonus the shears seem to naturally follow the score line, making cutting straight a breeze.

I do quite enjoy these offset shears.

They make quick work of these cuts, though admittedly at the cost of a bit of a forearm workout. But an hour or two later, everything is chopped up and I didn't need to stray into the other half of the sheet.

In the meantime the ERV showed up, but unfortunately it looks like it was shipped through a war zone.

This corner was bashed in far enough to jam one of the fans, and the collar on the other side was pretty solidly dented.

And oh wait, I guess it was shipped through a war zone.

Well anyway, they're sending out a replacement for free which should be here on Monday, so hopefully this one won't be bombarded by Putin's airstrikes.

In the meantime, let's take a little reservoir break before getting back to work.

Now that's refreshing!

So the first thing on the menu is going to be a ceiling duct boot, 10"x10" nominal (9-7/8" actual so it fits in a 10"x10" hole). The sides are going to be the most complicated part to cut and bend, so I'll call on the services of Bender Bending Rodrigues to help me out.

There's both box bends and some counter-bent flanges to deal with, and luckily a box-and-pan brake has features to accommodate both.

The main 1" flange here is to join to the top of the box, while the 1/4" counter-bent flange is just to stiffen up the edges and seat more nicely against the ceiling. The movable bending teeth give the main flange a place to go when this side bend is folded up, while the notch in the bed and bending leaf gives the counter-bent flange some clearance.

The two side pieces come together like this, and then we put a few break-bends in the top for reinforcement and pop it into place with some clecos to check how things are looking.

And next come the rivets to secure everything together without leaving those stabby sheet metal screw points on the inside.

Fun fact: if you don't deliberately rock the rivet gun backwards after each shot, it can jam up with rivet stems and then you have to pull everything apart to clear out the jam.

Anyway, I need two of these so it's second verse same as the first.

And that's the boots done. I'll cut the 5 inch holes for the collars later when I actually have the collars to verify the measurements. These will be going into my bathroom ceilings to replace the loud and obnoxious exhaust fans, which is why I chose to make them 10"x10". (One of the fans is unfortunately 12"x12" so I'll have to do some drywall work to patch around it, but there was no way to get a 12"x12" boot out of the sheet metal I got without cutting into the remaining 4x4 sheet, so I figured I'd go for consistency).

So that's the first prep week's work done, but there's plenty more to come so stay tuned for that.