I've seen some electric spa heaters that are only 1500 watts(1.5Kw) and 120 volts. How uch heat will this thing actually put out? Will it be enough to heat a 400 gal. hot tub a couple of degrees warmer? Say, the last 5 degrees to get it to 102*?
I've also seen Intex 3Kw electric heaters. These run on 240 volts though. They are pretty much only available in the UK though. First, will this put out enough heat to heat the hot tub? Also, can I just cut off the European plug and wire it straight to a 240v switch or timer?