biggreen1 wrote:I see most installs do not separate the two pipes and let them touch each other. I guess the overall efficiency would not change much. The hot pipe would tend to be a little colder being next to the cold return. But the cold return would be a little bit hotter when it gets back to the boiler so the water will not have to be heated as much. Any thoughts?
I agree with Yanche's comments above. I think a couple of points are worth making however. First, heat transfer between the pipes is a function of the temperature differential between the pipes. I think that typical systems operate with 20 degree heat drop--or at least that is a typical design parameter. The relatively low temperature differential tends to limit the amount of heat transfer. Second, heat transferred to the return line is not "lost". It simple reduces the net transfer from the remote boiler to the home. So long as you are able to get sufficient heat from the remotely located boiler to the home this transfer is of no consequence.