TY JOUR TI CALCULATION OF UNDERFLOOR HEATING FOR SELECTING A CIRCULATION PUMP KW water underfloor heating KW individual housing construction KW hydraulic calculation KW circulation pump KW pressure losses KW flow rate JO Construction and industrial safety AU Careva, O.S. AU Andreev, A.I. PY 2025 IS 0 PB V.I. Vernadsky Crimean Federal University