m1=0.5;
ms;
cp=4180;
Tin=45+273;
Tout;
To=26+273;
Tp;
Tm;
T1;
T3;
T4=60+273;
Pel;
Ptep=6000;
k=0.25;
kv=3000;
kt=300;
ϵ=2.5;
Δ1=+Tin-T3;
Δ2=-T1+Tp;
rovPredehrev={k*m1*cp*Tin+ms*cp*T1==k*m1*cp*Tp+ms*cp*T3,
Qpred==kv*((Δ1+Δ2)/2),
Qpred==k*m1*cp*(Tin-Tp)}
rovCerpadlo={Pel+ms*cp*T3+m1*cp*Tm==m1*cp*Tout+ms*cp*T4,
Qcerp==(T3-T4)*ms*cp,Qcerp==ϵ*Pel}
rovTopeni={T4*ms*cp==T1*cp*ms+Ptep,
Ptep==(((T4+T1)/2)-To)*kt}
rovMichani={(1-k)*Tin+k*Tp==Tm}

rovs=Flatten[{rovPredehrev,rovCerpadlo,rovMichani,rovTopeni}]

proms=Union[Cases[rovs,_Symbol,∞]]
Length[rovs]
Length[proms]

Solve[rovs]

45+273