Hi AC Hacker, mrd, Piwoslaw et.al.
Have been reading your exploits with much interest and thought I'd weigh in with my limited knowledge.
I too have been making and experimental HRV using plastic corrugated board (coroplast). Unfortunately, the only board I have lying around the house is 5mm thick so not as fine as a commercial heat exchanger.
The heatex core is approx 10" x 10" x 16" (at a guess... converting from millimeters in my head), layered alternately, and held together with masking tape. Good enough for a prototype.
I made the HRV cabinet out of coroplast as well though it still needs a layer of insulation. Internal cabinet height is size of heatex core across end diagonally and width is 16". The heatex core is placed in the cabinet diamond shape ie. corners towards the top, bottom and ends of cabinet. As the length of the cabinet is longer than height a divider is used to separate the core flows at each end.
The condensate drain is placed in the bottom of the cabinet on the exhaust (to outside) side. This is run off to outside guttering or drain.
Only problem I've had so far is fans. The 4" 12v PC power supply fans don't have enough force to drive air 20+ feet along ducts. Centrifugal fans are recommended for this and I don't have any in the parts bin.
Having worked for a company manufacturing HRVs (with Swedish HeatEx cores) my only regret was I didn't buy one when I had the chance... burnt bridges!
I wait with baited breathe to see how you overcome these issues.
With regards ASHRAE, you really only need to calculate the volume of your home (h x w x d all areas to be vented) and divide by 2 for a modern well-insulated home or divide by 3 for an older air-leaky home. This will give you the cfh (cu. feet per hour) required to exhaust and replace... divide by 60 for cfm. Air should be allowed to flow between rooms by open doors or door vents.
Sorry to waffle on... maybe pictures to follow.
Thanks for reading.
Mark
