We have made our decision re our new central air and would like some advice on the installation of the outdoor unit. I have seen several home improvement shows giving their commentary, that is mounting so to avoid settling and if needed work around the house without moving the unit. Our government site has the following suggestion; "In new construction, consider installing the central air conditioner outdoor unit on a frame mounted to the house. This avoids problems due to settlement of backfill around the foundation, which causes the outdoor unit to lose its level." FYI the unit we decided on was. 11 Seer Carrier Performance Series Model 38TPA018 Puron 1.5 ton Unit + Labour -$2600.00 with all required supplies. Electrical permit $36.00 1- Condensate Pump $150.00 Total with Taxes $2950.00 (Cdn dollars) Installed. What might also help is our location, which is Ottawa Canada. Thanks again.