Completing the Furnace Conditioned Air

In my last HVAC/furnace post, I had described the conditioned air plenum, and my efforts to create and then attach one. Today, I get on with the rest of the "conditioned air" venting. As before, I call it that so there's no confusion between the venting that has the output from the furnace and the venting that is the cold-air return side that feeds the furnace.

Rectangular Vent Prep

long arm

Recall that the crawlspace in this house had been infested with rodents. I mean it was bad. We had it emptied of rubbish and insulation by a team who seemed borderline hazmat. The work was disgusting, that team was amazing. They replaced some, but not all, of the circular vents with insulated flexible venting, but left the larger rectangular trunk lines. Perhaps they thought those vents were clear and clean or maybe they just wanted to complete the job (not that I blame them). Those vents were unobstructed, but far from clean. I had intended to clean them in-place with a microfiber cloth on an extendable pole. Once I got to really looking at them, I knew this was simply not going to be sufficient, and chose to ignore the fact that these vents were used last winter. Yuck.

ga-ross

To remedy, I dismantled them, and hauled them piece by piece out of the crawlspace into the backyard. Using the highest pressure setting on my hose-end sprayer, I jetted off the worst of the caked on filth, inside and out. Then, with a scrub brush and dish-soap, I cleaned each piece inside and out. Once rinsed, they were set aside to dry and I took one of my most-needed showers ever. The insides are clean, but I noticed a very slight brown staining. I concluded that it's probably from many years of people smoking tobacco in the house. I considered spray-painting all of the inside surfaces, but decided that the off-gassing of the paint was worse than whatever caused a stain (but was now gone). I did, however, spray paint bits of the outside of the venting which had rust or remnants of the old fabric (asbestos-imbedded?) tape which was removed by the hazmat guys.

Rectangular Vent Install

cleaned

Once cleaned, partially painted and moved back into the crawlspace, I was ready to start installing. I started at the furnace and worked by way out. First were the bits that connect the plenum to the rectangular vents. These are angled and change shape from one end to the other, converting whatever size hole you had in the plenum to the size of the vent. I found that by bending the lip wide open, the piece fit easily, and then just fold the lip back against the inside of the plenum. With high-end foil tape, I sealed the seams from inside the plenum.

I read about and considered using a brush-on goop to seal the seams but decided that painting goop while army-crawling around a filthy crawlspace just did not sound like a great idea. Consider too, the goop seals as well as tape, for the most part, and it's effectiveness is directly tied to user application. So, again, lying prone (or supine) with a brush of goop sounds like errors would abound. Taping is hard enough when you're lying down.

Once the 2 main bits were connected to the plenum, I first did a 90* turn bit on the smaller distribution arm (8 x 12 rather than 8 x 18) and then shifted to completing the larger arm. This took many hours, even though there were only 4 sections. For each section, I would wrestle the rectangle into the connectors on the end of the one prior. I used another section of HVAC to hold the far end up while I fastened the new piece to the old with sheet metal screws. Then, I suspended the far end from the floor with nylon webbing stapled to the floor joists above. Once free-standing, I sealed the seams with that high-end foil tape and then wrapped the vent with (R8) foil-wrapped closed cell HVAC insulation. I expected the venting to take a little while, but did not anticipate that the insulation step would take maybe twice as long as the venting assembly. I took care to seal up the insulation seams, but the time was consumed by, again, lying down and wrestling large rectangular insulation panels, trying to wrap them around a rectangular vent which had circular vents jutting out of it. I don't know if having the insulation sealed up tight matters much in the grand scheme, but I made sure they were relatively well sealed anyway. I spent probably 8 hours in total getting the larger arm assembled and insulated.

original round vent

Before I moved to the smaller arm, I attached the round vents to the larger arm. I had initially intended to remove the original remaining round vents, believing they were not up to snuff. While I was assembling the larger arm, I looked at the 2 remaining larger circular vents (picture on the right shows what condition they were in) and while there is some dust and more brownish stain, there is no rodent evidence. What I did not expect was just how close the rectangular venting is to it's original location. The round outlets on the rectangular vents are a few inches off center and less than a foot away from the original. So, I placed a short stretch of insulated flexi-venting between, taping both the inner hose and the outer insulation wrap at both ends. I did not capture a close-up picture of that, but I found that these sections were so short that it was actually easier to remove the inner sleeve from the insulation, attach it to both ends and then wrap the flexy-hose with the insulation jacket afterwards.

Smaller Arm

When I changed the vents around on the larger arm, I inadvertently removed the vent intended for the bathroom. I will re-integrate that later. The bathroom floor vent has not been connected since we first got the house. Recall above where I described where I made the cut in the plenum, I removed another vent access, which was direct-connected there, to the bedroom. Since it was not part of the air design plan for either arm, adding it to one or the other could upset the pressure for the other destinations. Since the bigger arm distributes to the west side of the house and the smaller arm goes east, I decided to tie it into the east (smaller) arm simply because that's the side of the house the bedroom is on. As it stands, the smaller arm only had 2 destinations (the kitchen and one main living space) so I felt adding a 3rd there would be less intrusive than adding a 5th destination to the larger arm. Also, I considered that the kitchen is an uninsulated space, cordoned off from the rest of the house with plastic. I decided to connect the bedroom to the used-to-be-kitchen vent in the smaller arm. When the kitchen is ready for a vent, I'll cut a hole and tie it in or I will move the bedroom connection back to the plenum.

short arm completed

The smaller arm took less time, and other than threading new stretches of flex-hose from the arm to the vents, it was a reflection of the larger arm work. Each arm-piece-to-arm-piece connection was metal-screwed in multiple spots, foil-taped and suspended with webbing. The entire arm was insulated with the R8 closed cell stuff, each circular connection was double-taped (inner tube and insulation jacket). The only real anomaly was with one rectangular-to-circular connector not aligning between the floor joists because of the furnace move. To remedy, I simply flipped it upside down (see picture on the right) so it is on the bottom instead of the top. I'm sure some HVAC person somewhere doesn't like this, but it fits, and it's sealed. All told, building the large arm took a weekend while attaching the circular vents to it and doing the entire smaller arm took a second weekend.

At this point, it had grown dark on a Sunday afternoon/evening. So, I picked up my tools and supplies and put everything away. With some scrap paper and a pen, I started contemplating the cold-air supply side. I will start that work next, but I think getting the "conditioned air" / distribution part completed was a significant milestone. Sure, I still need the gas hooked up, the exhaust re-assembled and suspended, the cold air return I just mentioned, the trigger wiring done and, last, the electrical (and walk thru by our electrician / HVAC guy). Yes, that is a lot, but I feel like the largest, hardest part is now behind me. I know... "famous last words".

Thanks, as always, for following along-

New Seat, What a Treat - Part 3

Today, I'll complete the story of getting the driver seat stripped, recovered and installed. When we left off (See New Seat, What a Treat - Part 1 and Part 2) , the old covers had been removed and set aside with the old padding, hog rings and ratty hard-back. The upper seat had been re-foamed with a heat unit, and recovered with a new hard-back. Now held in place with hog rings, it is a completed unit.

Back to One Frame
Before getting to the lower seat, the upper and lower halves need to be put back together. This is quick work with a couple of 1/2" spanners per side. Over each of the hinge points, a plastic protective cover is installed. These keep fingers, cover material and grime from getting into the hinges. They are held on with a single Phillips screw each and are side specific. I had washed these with dish soap, removing 30 years of gross beforehand. At this point, I tested the action of the seat release lever and the movement of the hinge to make sure nothing was binding and that it had a smooth movement. Check.

Lower Seat - Webbing
The upper cover was similar to a pillowcase, with an opening at one end (the bottom). The lower cover only has 4 sides: top, front, left and right. So, it is more like a fitted table cloth. No forceful stuffing to get everything to fit this time. While that sounds easier, the material does not stay put as easily, so I found myself double and triple checking everything at each step.

First, we start with the webbing. I found little advice for how to do this, and based my entire plan on pictures I found on the internet (like this one on the right from MGExperience). The webbing has 4 straps which run left-right and 2 straps which run front to back. These straps are loosely threaded onto a thin, 3-sided, u-shaped metal bar (I'll refer to as the U-bar). The replacement kit arrives with 12 little hooks which hold the webbing contraption to the lower seat frame. The frame has 16 little holes: 2 along the front, 2 along the rear, 5 along each side... and one in each front corner. Apparently, those corner 2 are unnecessary and there is an extra pair along the sides for personal comfort configuration. The bottom of the "U" faces the front of the seat, so the 2 holes in the rear of the frame are for floppy straps that are not dire-connected to the thin metal U-bar. I started at the front, threading one hook each through the gap at the end of the strap, around the U-bar and then into the hole in the frame. With the front done, I worked my way down to the rear, doing holes a strap at a time, one side, then the other. I left the last pair, closest to the rear unused, choosing for the more forward pair thinking it would be more supportive. Last, the rear-end of the straps are hooked into the frame. To help prevent the straps from cutting through the foam, I put a small thin white hand towel on top of the webbing. Others use burlap or canvas. The hand towel was available, free, fit, and will do the job at least as well. There was nothing between the foam and the webbing when I tore the seats down.

Foaming
Unlike the upper seat covers, the lower seat covers and foams are side specific. On the underside of the foam, you will find either LH or RH embossed into the foam. This is because the little notch-outs nearest the seat hinge are not the same. Also, the seat edge along the transmission tunnel is more straight and narrow than the seat edge which runs along the door sill. This allows the seat to move forward and aft on the seat guides much more easily, without hanging up on the transmission tunnel. Since your backside sits in the wide center anyway, you may not really notice. The covers are cut differently, just as the foams are, so match them carefully or you'll be re-doing part of the job. Ask me how I know :)

Lower Seat - Covering
With the webbing in, I pushed the lower seat foam onto the frame and took a seat. Wow. It was like the difference between an old saggy couch and a nice new desk chair. Firm, but totally comfortable; I felt I could sit in it for hours. Those few minutes were inspiring. I pulled the foam and attached the other seat heat unit to it. Similar to the upper, I didn't cut the heater. Instead, I ran it from just behind the front edge all the way to the front edge of the upper cushion. I'll have warmth from the back of my knees to the top of my shoulders. Ha! Once I got the double-sided tape figured out, it attached and held well through the process. For more wiggle room, I tilted the seat upper slightly forward. I took out the new cover, oriented it where it belonged on the foam/heat unit pair and pressed it onto the frame. I say "pressed" because with the seat upper, it took more than just setting it. There was resistance to my getting it all the way back in place. Again, there were many cycles of fitting, adjusting and re-fitting to get the foam aligned with the seams. Minutes taken here are where you'll see the difference in the finished product.

Ring It Up
With the seat bottom where I wanted it, I tested it again (Ohh.. soo nice). If you are following this as a how-to, I strongly encourage you to try this in-the-car! You may find the seat too high. I, regrettably, didn't do this test. Instead, I started on the hog rings. I made sure the heat unit wiring was on the transmission tunnel side, like the upper. With the seat upper helping hold the rear in place, I started there (along the rear) with the rings. Like the upper, I pulled the material until it was well aligned and put 2 rings about a fist apart in the center. Again, following the pattern from before, I did each side of the rear, checking for alignment. Then, I switched to the front, and followed the same pattern: center first, then outer edge, checking for alignment, no wrinkles, etc. Last, I did the rings along the sides, starting with the edge nearest the transmission tunnel. Since the hog ring pliers I got at Harbor Freight were useless, I used my fingers to get them in place (not easy) and channel-lock pliers to snug them down.

Install
So, there were things I did, and things I would encourage others to do differently. I changed my disposable gloves often so I would keep the seat clean. I covered the seat with a large trash bag for the same purpose. One of the things I had failed to do was test out the seat in the car before hog-ringing the lower cushion. Had I done that, perhaps I may have omitted one or more of the webbing straps. I say that because with all of the straps in, and the seat tilted fairly straight up, my line-of-sight out the windscreen is too high. Since the straps are what hold the foam up, I could have tested, removed one, tested again, etc before putting on the cover.

Instead, I carried the finished light-cream-colored seat into my cramped, filthy garage. I held it overhead and found that getting it into the car with the top up was simply frustrating. So, the seat went onto the dinner table while I lowered the top. Take 2: carry the seat high overhead, lowering into the cockpit. For some reason, all of the challenges I expected when I put in the old seats on top of the new carpet happened this time. I couldn't find the holes, then, when I found them, I couldn't get the bolts to thread. Then, once they were finally threaded, I realized that the seat runner was oriented incorrectly.... Last, one of the worst things happened: the front outer bolt and captive nut pairing got stripped.

Fix It

The bolt wouldn't come out of the captive nut, so the captive nut had to be separated from the new floor.... while holding my light-cream-colored seat loosely on top of it. I went the brute-strength method and used a pry bar. In retrospect, this was a great test of the welding of the floor we had done; the welds held better than the sheet metal. The nut released from the floor, the seat was returned to the table and I went looking for a replacement nut. I found one, and, with the welder I had used 18 months earlier to install the floor, I welded that nut into the hole created by the removal of the old one. I covered everything with canvas painting tarps before I welded so any possible errant spark would not land on my new top or new carpet. Since the top of the new nut didn't sit exactly flush with the floor, I slid a washer on top of the other front seat-mount hole to level the front of the seat. I left it alone overnight and the next day the seat went in easily.

I fiddled with the seat incline and found a spot that, while tilted a little further back than I usually drive other cars, the angle totally suits the MGB. This little car has a deep foot well and a short reach of the steering wheel, so it is almost designed for someone who has long legs and a short torso and arms... until you tilt the seat back a little bit. Now, instead of having the steering wheel nearly against your chest, you have some living space... and the angle lowers your line-of-sight through the windscreen such that your eyes are below the sun visors.

That's it for today. I will wrap up with a post about the head rests. Thanks, as always, for following along-