I ran my spa on 110 for years and loved it! it was an 7'8" model and yes it did lose heat, about 1 degree every 10 minuets with the jets running. When I got my first 220 spa I liked it even better. The bottom line is that the spa is convertible. Try the simple way, if you like it on 110 keep it that way, if not pay for the upgrade latter. What the upgrade consists of is an additional 220 sub-panel that can be added later. The instructions for the conversion and the schematic for the sub-panel are both in owners manual and inside the control panel cover.