The Freshening Part 5

So it's about time I got this project fully wrapped up, and a little ahead of schedule as I managed to get an early start today which meant I could burn some time before lunch, and thus before the attic turned into an inferno that would cook me alive as soon as I poked my head up above ceiling level.

Of course, the first task didn't even take place in the attic itself, but rather in my car hole, where I bent up a piece of sheet metal into a 5 inch round splice.

Fun fact: you can make round things on a sheet metal brake... Well, sort-of-round things. Round enough.

Anyway, that piece goes in between the too-short piece of duct I installed a few days ago and the new piece of duct that arrived on my doorstep.

So this area over here is no longer a hideous octopus of aluminum foil ducting.

And what did I do with the remaining 15-or-so feet of duct from the 25 foot box?

I shoved it back in the box. I'm sure I'll find a use for it at some point. It can live up here until then.

Speaking of boxes, I installed the relay box which allows me to adapt the 120v timer switches I installed last time to the 24v control lines that the HRV uses.

It's just a pair of relays with 120vac coils (which is apparently a thing) wired up exactly how you'd expect them to be.

And good news: even at full zoot with the "Taco Tuesday" button switched on, the HRV is still barely audible down in the occupied portion of the house. In fact, I think removing the duct-o-pus from the output actually made it a bit quieter than it was initially, which is pretty sweet.

So the only other question is: how efficient is this HRV? Well, it was a little over 28c outside the other day so I pointed my thermal camera at the fresh air vent.

Hmm. Well, I guess I can't really expect miracles when there's only 4 degrees difference between the inside and outside temperature. And, let's face it, this is California; the main goal here, which I achieved, was getting more air circulation inside the house without having to open the windows and let a bunch of pollen and pollution in.

But while I've got the thermal cam out, let's see how the insulation in the car hole is performing (which is still an ongoing project).

Well now that's a bit more of a dramatic difference. The face of the insulation (left) is only 25c while the underside of the roof (right) is roasting at 42c.

Now that the HRV project is done, I'll hopefully be able to wrap up the insulation project over the next few weeks before spring really kicks into high gear and the hot days become more inconveniently frequent.

But in the meantime I've got some fresh air to enjoy.

The Freshening Part 4

When we last left off on our HRV installation adventure, we were staring at the underside of a piece of cardboard blocking up a hole in my ceiling that was a bit too large for the vent that was about to go into it.

Since this will be another long one, click through to continue reading.

The Freshening Part 3

Parts have arrived, the week has been booked off, so let's get things moving for real. We'll start by yeeting the HRV up my shiny new attic ladder.

But because this will be a long post, not until after the break. Click through to continue reading.

The Freshening Part 2

If I'm going to bring fresh air into my house, I want it to be actually fresh, and that means I'll be filtering out all the pollen and pollution that tends to be mixed with the outside air. To do this, I'll need a filter and, more importantly, a plenum to install the filter into.

So it's back to the sheet metal grind to use up the other ~3/4 of the metal I cut up last week. A basic box is a good place to start.

As we can see this is sized precisely to fit a 12x20x1 filter diagonally inside the 1 inch flange. Coincidentally, the size of plenum needed for this fit is 12x20.

Go figure.

Anyway, the removable fingers of the box and pan brake are really coming in handy here, especially when it comes to the double-fold on the door panel.

It's actually going to fit folded side out to the front of the plenum so that the flat panel sits up against the side of the filter, otherwise the air would just blow right around it through the gap.

And we can also see the rails in this picture that the filter will slide into.

Those rails get riveted to a set of corner panels, and a pair of braces goes lengthwise between them to support the filter and block the air from going around the edges.

And the whole assembly will look roughly like this.

But that's going to need a lot of rivets, so before we get there let's take a quick newt break.

And refreshed from that, I'll add the cross breaks to the panels. I had initially contemplated not adding them as some of the panels were slightly too large to fit into my brake diagonally, but in the end I decided to go for it and employed the other method for adding cross breaks: using a window screen roller.

Which works surprisingly well, all things considered.

Then, about a hundred rivets later, everything is secured together nicely.

Was it actually 100? I don't know, feel free to count up the stems and let me know.

I do still need to attach the door to the plenum. I already have the hinges and latches, but I want to get the weather stripping first so I can space things out correctly.

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.