Saturday, August 20, 2016

Eberspacher Hydronic MII Install

It all started with finding an auxiliary fuel tank to feed both the generator and the hydronic furnace. What we ended up with was a custom 50 gallon aluminum marine stern tank we found used for $225 that I had the width adjusted to 84 inches to fit in the cargo bay. I also added a sight gauge on the fill side along with a return fitting for the diesel generators fuel return line.    

The wiring harness was anything but straight forward. Customer service is seriously lacking when it comes to dealing with the direct consumer instead of flleet mechanics or dealers but I was able to find an old O&M manual that gave a pretty close idea of a wiring diagram for the harness to controller interface. mounting the controller was a breeze.


After a lot of deliberation, I decided to mount the furnace in the opposite bay to the generator to simplify fuel delivery issues as well as access to the coolant lines which had been previously tapped for some previous accessory. I also installed a Racor filter/water separator to keep things clean. Intake air is drawn from the adjacent bay while exhaust exits the passenger side via custom hangers and a 3 1/2 inch marine thru hull. Exhaust temps are about 450 degrees on high and it takes around 45 min to heat all the coolant in the coach to around 160 degrees without ever starting the engine. All this heated coolant costs .05 gallons of fuel per hour on high and can be used as a very efficient source of heat on cold days or through the heat exchanger in the hot water tank. So far this has been my favorite and most time consuming upgrade considering I've been buying and installing parts for this system for three years.  

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