Naam, how deep do you have to go to get 18ºC water in the Pattaya area?

i'm at 33m but i don't think there is a big difference between let's say 10 and 50m and that applies also to different areas and countries. for irrigation purposes i had a well in Germany, depth approximately 15m, water temperature a steady 16ºC at an ambient temperature of -15º in winter and +30º in summer.

From memory, the esteemed company Electrolux, has been making these devices for approx 75 years or longer. One of the main problems is the COP (coefficient of performance = energy out / energy in), which may be slightly more than 1.

Electric aircons typically have a COP of 3.5, although some people maintain 4 is possible.

Anyway, as some posters have mentioned, the fuel cost is important, and also the calorific value of the fuel. Gas tends to have a lower calorific value to oil --- maybe 0.6 ratio, therefore the fuel price has to reflect this.

But, as all things in life --- up to you.