Coriboard Heat Exchanger

When I moved into my new house, the first thing I noticed was the dampness. The previous owners had told me already that this was a problem for them and the place was damp no matter how much the heated it ! Straight away I knew what my first plan of action was : Ventilation.
Place place had none whatsoever and with heating cranked up to max, it is no wonder it turned into a fish tank in the winter months.
You can make a pretty effective ventilation system using simple computer fans and some fexible tubes. However due to lack of time -and lack of fans, I got a small simple ventilation kit unit from ebay instead. A simple one is more than enough for a whole small to medium house (mine's a bungalow cottage). Theres absolutely no need for the big industrial size ones some company offer these days. These are overkill and expensive. worse, I've even heard of people having to install humidifiers in the house after installing one of them.

Since it was summer there was no rush for the heat exchanger part so I had time to build it myself. When I enquired, I found out that most were build from coriboard sheets stacked. Luckily, these are easily available (just wait for the next election, referendum and grab ones that were blown down by the wind...)
Cut them in squares -40x40cm is what I did, and stack them so that the ridges of the next layer are perpendicular to the ones of the layer underneath.

Make sure they're glued tight so that no air can go between the layers. I used a spray glue, I can't remember what it was, but it's readily available in most hardware stores.

 Once you got a stack of 40 layers or more, I build a case and fitted the stack in a diamond pattern inside the box. Make sure to seal all joints and edges with silicone.

Close it, leave to dry for a few days and there you have it... a perfectly functional heat exchanger. 
The idea here is that warm damp inside air comes in from one of the brown tubes, enters the ridges of the stack aligned with the tube. At the same time cold drier air comes from outside into one of the back tubes and enters the stack where the ridges are aligned with it. Since each layer is perpendicular to the other, heat exchanges and you get warm air back into your rooms.

The concept is that the fan extracts warm damp indoor air from places like the kitchen, near the bathroom and let the damp warm air escape. Since the extraction creates a vacuum in the house, cold air is naturaly sucked back into the house from outside. You want to make sure your house is air tight then and have holes in your dry room ceilings (bedroom, office, living room) so that air can come back this way and circulate naturally in the house. Since the air flux exchange heat (without mixing) in the exchanger you're getting warm dry air back in your rooms.

Election Posters Surfboard

I got the idea, while looking up for a way to make a cheap heat exchanged system. The idea is quite simple, take some of those plastic election poster that plague the countryside, overlap them so the grooves are at a perpendicular angle on each layer and voila... a simple heat exchanger:
http://www.autoconstruction.info/La-fabrication-d-un-recuperateur.html?artpage=4

When I tried this, I realized that by overlapping the layers that way, you get a structure strong enough to support my body weight, yet very light. Straight away I thought... Surfboard!!

We're not talking performance board here, but sth you can bring out on crappy days or lend to one of your visiting friends. Beats using a soft board or buying a bic.

So it's quite simple really. First you need to take a few of these. I took some of the wind fallen ones first, then waited until the election was over and asked one of the people who were taking them down. They're all 4ft long, not that it matters too much as we'll glue them together anyway. Fibreglass and resing will then provide structural strenght.

Note that it works just as good with the YES side of the campain... these were the first I got.


Then the next step is to glue them together.
One layer must have the holes in the board facing one way and the other layer at a 90 degree angle.
A simple utility knife will cut them no bother.



I use some spray glue for this. Ask your local hardware store for what glue to use.
You want the boards to really stick together as you'll need to saw and plan the block into shape after.
Here's the glue I used. I like it because it's easy to apply, you don't need a brush or a big tube, it doesn't leave a mess and pretty much sticks in seconds.




I continued to glue the panels together until I had a 8ft long with 6 layers "surf blank". In this first try, I left out some of the panels near the far ends of the blank in order to make it easier to creat the rocker. In hindsight it's much easier to make it all one block and then plan the rocker later.


Next is the cut.
I took one of my board and drew the outline onto the blank from it.
I thought I'd use a handsaw for this but it proved messy. A jigsaw seems to make less of a mess, if any at all.


You can leave the tail for last but I was so anxious to see the full shape of the board that I cut the tail anyway. You want to watch out from then on. Those tails a fragile so they need to be handled with care.


Next I started shaping the board. I initially though a sander would a lot more gentle on that corriboard material. However it turns out a planer is definitely best.

The cuts are sharper and don't leave a mess. I forgot to take shots of this stage, so here's a few pics of what it looks like after the first bottom glassing.

Since I wanted to paint over it, my next step was to find a way for the paint to stick onto the material and do a few tests

I had some leftover of resin bought at the local hardware store and an old bed sheet.
I thought I could use that at the bottom of the board to act as a canvas for paint.


This wasn't such a good idea at the end as I didn't have enough resing and the bed sheet is nowhere near strong enough for this.
The whole thing looks ugly and started delaminating as soon as it dried. Here's a few photos for posterity :)



I like the idea of using old bed sheets for this but it simply doesn't work. I will strip the whole lot and glass it properly next.