Last week I fired up my 4 ton Tranquility 27 system and after 5 days of collecting data I wanted to check with folks about the delta T I'm seeing on the enter and leaving temperatures of the loops. I'm located in Western Massachusetts, the loops are ~7' down and are 3200'. When running in heating mode I'm consistently seeing a 4.2 degree difference. Is this OK? I've looked at a number of folks's WEL graphs online (http://www.welserver.com/) and 4.2 looks consistent with others, but being a new-bee I'm kinda curious what I should expect to see. Thanks -David

Delta-T is mainly a function of heating load (i.e. stage1 versus stage2)
and flow rate (GPM); it has very little to do with the loop field itself.
If you're concerned with loop field performance, pay attention to EWT
alone. If it doesn't get too low (during heating season) the loop is
doing its job.

FWIW, a 4.2 F delta-T sounds about right for a closed loop Tranquility 27
system running in stage1 within the CM-recommended flow rate range.

Sounds good, perhaps even low, to me as well. What is the EWT?

Thanks for the feedback already received. 

Update:  I changed the position of my temp sensors tonight and the delta T is now 6.3 rather than 4.2.  So, this is entirely within the range recommended by Climate Master for this heat pump.  The issue appears to have been related to trying to measure temps through the plastic pipe, once I put the sensors on the metal fittings used to couple the pipes to the circulation pumps I got what seems to be a more accurate reading.