To be honest HEET is nothing but Isopropyl alcohol, But it really depends on how much water was in the tank, Although with the introduction of ethanol in our fuel these days water from condensation really isn't such a problem, as it absorbs water just as well, Did you do something really dumb like dump water in your tank? That can in the garage you thought was fuel turned out to be water? If that's the case all the alcohol money can buy wont solve your problem, your going to need to drain the tank and flush the fuel system, Sorry.

Depends on source of heat. Temperatures I loved. Nearness of fuel lines. Insulation, material of lines , air flow around etc

Are we talking about say a diesel car that has heaters in fuel line? Petrol car that us suffering from heat in fuel lines?

More specifics will enable a better answer eg make. Model. Year. Fuel type , section of car or area involved any issues?

It is over 80 degrees Fahrenheit today. Why would you need "Heet" in your fuel?

HAving troubles with water? Next time, dump a half bottle of isopropyl alcohol in the tank. Cheaper and works just as well.