Hi all- Been reading this site for a while, great resource, finally have a question of my own. We built our home in 2010. It's 2 stories plus full finished basement, approximately 5000 sqft. 2x4 exterior walls with spray foam insulation, Anderson 400 series windows, R42 in the attic. Having been used to the high gas prices of the early 2000s, we took advantage of the tax credit to have a ClimateMaster Tranquility 27 (5T, closed loop) installed. I did not have the time, foresight, or know-how to supervise the install. It's been mostly trouble-free up until the last couple of years. The blower was replaced last summer (parts under warranty), and around the same time, we had an incident or two where the reversing valve would not switch to cooling. Thankfully the latter issue disappeared, because it would have been a very costly repair. This past summer, the unit went on high pressure lockout. I power cycled a couple of times to no avail. I called another company this time. He and the first technician both told me the same thing: the fly-by-night company that installed our unit was notorious for installing undersized loop fields. His diagnosis apparently corroborated this. Here are the notes from the call: Unit was locked out on a high pressure fault upon arrival. Reset power. System kicked on. Tested loop. PSI drop off 4 psi. Entering water is at 20 PSI. Leaving water is at 16 PSI. 12° temp split on loop. Entering water temp is 84° Leaving water temp is 96° Unit is moving 15 GPM. Both loop pumps are working correctly. Recommend adding water to the loop to bump up loop pressure. 80 uF compressor capacitor tested @ 78.9 uF. Pumped loop up. 56 PSI IN. 52 PSI OUT. 4 PSI drop. 84° IN. 96° OUT. 12° spilt. Unit is operating @ 15 GPM x 12° split x 485 brine = 87,300 BTUs This is way too high. Unit is rated @ 64,000 BTU. It appears there is an issue with the side of the loop in the ground. Unit is cooling with a temp drop of 23°. He said it was possible to add more loop, with the associated cost and destruction of the yard. Adding on, we've had a cold snap these last few days. I've been watching my desktop electric meter, and it's been running on backup nearly the whole time. Our electric bill can reach $450 after a very cold month (appx. $300 of which is heat). I am all for efficiency, but wonder if it's performing even close to how it should. Plus, parts availability around here is terrible, and most companies aren't very familiar with them. Knowing what you all know, should I kick this thing to the curb? Is it costing me too much money to operate, and/or is it a ticking time bomb? It would not cause a financial hardship to have it replaced. Greatly appreciate any input.