SetDirectory["FileName"/.NotebookInformation[EvaluationNotebook[]]/.FrontEnd`FileName[d_List,nam_,___]:>ToFileName[d]];

struct=<<"struct";

Pel[Tvzduch_,Tvoda_]=struct[[1,1]];
Ptop[Tvzduch_,Tvoda_]=struct[[1,2]];
eps[Tvzduch_,Tvoda_]=struct[[1,3]];
Pel[Tvzduch,Tvoda][[2,0,1]]

Plot[Evaluate[Ptop[Tvzduch,#]&/@{35,50,60}],{Tvzduch,-20,25},PlotStyle->Thick]

c=4186;
rce1=Ptop[Tout,T3]==m1*c*(T3-T4);
rce3=m1*c*(T5-T3)==Pk;
rce4=m1*c*(T5-T4)==Qtop;
rce5=Qtop==kTop*(((T5+T4)/2)-Tin);
rce6=Qtop==kDum*(Tin-Tout);

rceStav={rce4,rce5,rce6};
Stav={Qtop->7000,Tout->-12,Tin->22,T5->40,T4->35};
dos=Solve[rceStav/.Stav][[1]]//N

dosrce={rce1,rce3,rce4,rce5,rce6}/.dos;
Length[dosrce]
Length@(Cases[dosrce,_Symbol,∞]//Union)
Cases[dosrce,_Symbol,∞]//Union

prores[Tin_,Tout_]=dosrce;
prores[24,-10]
Cases[%,_Symbol,∞]//Union