Introduction: Project AHU
This project is a manual for any and all who want too duplicate what we have done in our efforts to make a cheap and easy modifiable small scale model of a air handling unit.
For the code and further documentation this subject go to:
Step 1: Design the Case
In conjunction with the project owner we made a design for the case. This was first done on a whiteboard and later worked out as a 3D model in sketch up. During this step as well theorized the potential size of the case. However since we did not know the final dimension of the components that would be installed in the case we did not finalize it.
Step 2: Buying Materials.
After finishing the research and coming up with the dimension we made a diagram with those dimension. After that and with those measurements we pieced together a plan to cut out the pieces out of one piece of 40 mm thick 122 cm by 244 cm piece of plywood. However while buying the materials we observed that 40 mm thick would be too thin for making a sturdy case. So we went and bought 90 mm thick. This had the unfortunate consequence that since the sides are now 50 mm thicker the original plan won't totally fit. For us this wasn't a problem since the place we bought the wood made a mistake while cutting and we got a sheet for free so we had enough extra material to make up for it. But if you are replicating this build you might want too look for a bit extra plywood. These where cut in to the large pieces outlined in the plan at the shop. We as well bought some nail however we later swapped to screws for the structural parts to increase the rigidness of the case.
Step 3: The Box
We started with the box. First we drew the holes for the two tubes for incoming and outgoing air. The bottom one being round for installing the fan there. We cut out the window at this time and glued a piece of Plexiglas to it. At this time we realized that just sticking them together with some glue and nails would not give the desired outcome and would probably end up breaking at some point. So we cut up a piece of 1 by 1 stock and attached them to the underside and 2 of the sides of the cube to then attach them and the other too pieces together. These where all glued and nailed with multiple nails. Then where held together with clamps until the glue was dry.
Step 4: In-late and Out-late
Since we wanted the case to be modular as possible and add components in at a later stage. For this purpose we wanted the top of the tubes to be removable but since the bottom tube supported the top one we installed struts to support the upper tube and some support at the box side. As well we installed the 1x1 strips to support the tops of the tubes since these aren't nailed and glued in. All the struts have been screwed in place to get some extra rigidity, the rest of the joints are nailed and glued.
Step 5: Finale
When all this was done we had the skeleton of the air handling unit. This was far from a final product but everything after this highly customizable too your specific needs.
We installed for example a raspberry pie, which was mounted to the front and wiring too the varies components. Later we drilled holes for the wires too run to the different components, this are examples of how the placement can be done, but are in no way the best or optimal ways.