Webasto question

[eagle10]

I finally got my Webasto unit running great after a 10 week ordeal. I shipped it off to Bus Services in Kansas and they rebuilt it for a fair price. The first place told me it was junk and I needed a new one. It is a Webasto 2020 unit out of a 1992 Liberty. Bus Service replaced the wiring harness on it for some reason which created a huge problem as we had marked the old wiring when we took it so we could just plug it in again. Two days of chasing wires and we finally solved the wiring issue.
Question now??? It has two circulating pumps on the system. The pump in the back by the engine is not working but the front one works fine to circulate the water in the zone for the interior heat. The pipes get hot until they branch off and go to the water bay for the hot water tank and the heater in the bay. The valves are all open but no hot water ruunning through to the bay. It pumps hot water through the engine and out the other side till it comes to the zone heading to the hot water bay. Any ideas???
Both my GMC 4108 and Eagle 10 had propane so this Webasto is new to me.

[Bill B /bus]

There is a valve in the way that is causing the no flow condition. The valve could be open diverting flow or closed preventing flow.  Make a line drawing of your system showing all connections and components. Most systems are built with a summer loop and an all component loop. The idea being that in the summer loop you will have the Webasto, hot water heater, surge tank and circulating pump, this prevents excess heat from overloading the AC.

Re: second pump is for preheating the engine. The pump is normally set up with an on/off switch which both controls the pump and acts like a themostat to enable the Webasto to provide heat for the engine preheat. 

Bill