Hello, I'm having an issue transferring heat from my outdoor boiler thru a 50 plate heat exchanger to my indoor Burnham oil boiler. I have 175 degrees on the feed line to the heat exchanger. The return line is 165 to 170 degrees. I turned the Honeywell controller on the Burnham down to 140 and can't get the temp in the Burnham to rise using the exchanger. I bled the lines, several 5 gallon buckets but could never get the water crystal clear. It always had some color to it. Should I have clear water after the flush? Should I shut down the boiler while doing so? I'm concerned that I still have air in the line or that the exchanger is dirty from the brown water. I'm also concerned about the 007 pump being too small between the Burnham and the exchanger. Please advise, looking for help.