The reason I have a 2 pump flow center is that I was able to get that center for the same price as a single and even with just 1 pump running the flow was what I needed. I can turn on both pumps and purge the loop pretty good. With the latch relay circuit I figured the pumps would last a long time since they are alternating the work. Maybe not the best design in hindsight, but for the first 1.5 years the system has worked great! I have checked to see that only one pump is running at a time and that is the case. I have also slowed the flow to see what difference that would make and it made a 1 degree difference in the LWT but no difference in the temperature of the air being sent to the living space. I feel pretty confident that the field and pumps are not the problem ( My incoming water temperature is good). I think it might be time to have someone come and check the refrigent levels as you have suggested. Thanks for all your help and I will let you know what I find out.

Best,
hp