Bill: Since at least the 1990s. Within the OPE arena Champ (easily identified) has for decades pretty much does OEM'd for all the OPE manufacturers (I'm aware of 2 small exceptions). Tell you what - why don't you show us someone the DON'T OEM to... If Allied Signal has made inroads this is a new development.

YYour systems need fresh air to be efficient. If units blowing up a tree do not need to block air flow or it with return back to the system MFG rule of thumbs if units is 36" tall at less 36" from ANY plants ( but being a service tech. We love dirty unit and lack for air flow "SERVICES CALL" OF DIE SYSTEMS. UNIT THAT CANNOT GET FRESH AIR TAKE AWAY EFFICIENT. COST YOU MORE MONEY ON YOUR LIGHT BILL. TREE SHADING UNITS MEAN ON RAIN TO HELP CLEAN THE COILS. COVER UNIT NO ROOM TO WORK ON OR TO WASH THIS UNIT WILL PUMP THE OIL OUT OF THE COMPRESSOR :) MONEY :) TO MAKE. PS IF NEW SYSTEM THIS WILL VOID ANY MFG WARRANTY.

Well I'm back, after having consulted with 2 geothermal installers. One is doing a complete load calculation and evaluation for geothermal versus an air-source heat pump, for us to compare against the quotes we have for just doing a/c. The other guy won't do a full analysis, including potential cost savings based on our individual usage patterns, without us paying a large fee for that service (US$700), but he was definitely there to try and sell it. Both gave a ballpark of the cost being about 3x (at least) of our a/c-only quotes, and both said that we'd have to have a split system (two systems?)--one in the basement going up to the first floor, and the split being in the attic coming down to the second floor. And because of that, the cost goes up. The first says we have enough room to trench, while the other says he prefers drilling vertically, saving horizontal loops for unlandscaped/non-lawn areas (like for brand-new construction). Both did say that our access in our unfinished basement and attic are generally good. We have one more home visit by another geo person, but I can already tell that my husband thinks it's way out of reach, though he loves the idea of geothermal. He's now back to thinking that we should just buy window a/c units, as the easiest and cheapest option (he also thinks it would be more energy-efficient if we only get 2 for the hottest 2 rooms). I guess I won't discount geo until I see a hard number from the first guy and compare it to the air-source heat pump option (which I had not considered, either). But there's the update, anyway. I'm very envious, Pyropaul, that your cost did not end up being prohibitive for your old house retrofit! Do you have a split system, too?

Sorry the furnace had two numbers on a sticker attached to the side. The first is TUH2B080A9V3VAB the second is 9391NGP1G. All of the units quoted are 3 tons. The manual J came back for a three and a half but all three said that the current ductwork would not support the larger unit. Also, they all asked how comfortably the house heated and cooled. My lot has a lot of trees and I feel like the house was very comfortable both in the winter and summer. My highest electrical bill during the summer is usually around $220. So based on my input and the fact that there would need to be major ductwork they all felt comfortable keeping a three ton unit. Let me know if you need anything else or if those are not the right numbers. I am about as ignorant as it comes where HVAC is concerned. Thank you