ChemiX is a new generation Bragg crystal spectrometer intended to measure X-ray spectra from solar corona. The instrument is under development, and will be attached as one of the scientific equipment to Russian space solar observatory Interhelioprobe. The final heliocentric orbit will be reached after cruise phase which involves exposing the observatory to varying thermal conditions during the whole mission. Final scientific orbit is highly eccentric which results in substantial changes of solar heat flux. The power dissipated inside the instrument itself has also significant impact on thermal conditions. Furthermore ChemiX, as a component of whole spacecraft, will receive and give back some heat due to conduction to the main structure.<p> </p> Proper evaluation of temperatures and heat fluxes in this case is not only important for correct performance of ChemiX but also for success of whole Interhelioprobe mission. To evaluate those parameters a steady state analysis in satellite crucial position was provided as well as computer simulation.