[jtroutma]

Looks really cool.

That should preform quite nice.

If you are up for them, I do have some recommendations for better efficency though.

First, I would try and add some sort of shroud between the fans and heatercores to avoid some "dead" spots in the heatercores.

Second, the plumping looks good; dual serial connections in parrallel. Personally, I would rework it so that all four of your heatercores are working in parrallel. That way the water will be the "hottest" in all the heatercores and can cool them more efficently than having the first heatercores cool the water, then the second heatercores cooling "already partically cooled" water.

Keep up the great work.