To combine two separate ground loops? I have two 4 ton climate master heatpumps. 1 servicing the upstairs and the other servicing downstairs. We live in the Seattle area so summers are not taxing on the system and winters are not too severe. We have 4x100 foot slinky loops in the back yard for down and the same in the front yard for up. Our problem is that in the winter, the downstairs unit's supply air temp is 5-8 degrees cooler than the upstairs unit (of course the downstairs unit has a larger heating load in the winter). During the summer, the downstairs unit's supply air temp runs 9-11 degrees cooler when cooling. (of course the upstairs unit has a larger cooling load) Based on the unit having the largest load not performing as well as the "off load" unit, I'm thinking that the loops may be undersized. My question is....would it be possible to combine the two loops into one? The heatpumps are on two different levels, but both sets of header lines enter In the crawl space. Another piece of info. In the winter, the downstairs unit ice's heavily, upstairs barely any frost. In the summer the upstairs entering coupling is warm to the touch. The downstairs unit barely has a perceptible difference between the incoming and outgoing connections in cooling mode. Since the "off load" pump tends to run roughly 10 and 20% of the time in the summer and winter respectively, the extra capacity will feed the main heat pump and not let the combined loop over cool or heat.