  Context: Episodic accretion plays an important role during the early phases
of star-formation. The main processes responsible for the episodic accretion
events remain, however, unclear. Aims: Our main objective is to investigate the
properties of FUors and EXors by analysing observational data, along with
numerical hydrodynamics simulations of protostellar disks, stellar evolution
models of outbursting stars and thermo-chemical models of star-disk systems in
the outburst state. Our goal is to get a better understanding of the outburst
processes and their respective origin. Methods: We used the radiation
thermo-chemical code ProDiMo (PROtoplanetary DIsk MOdel) to match the dust
emission and gas emission lines originating from the environment surrounding
the FUor star Re 50 N IRS 1. Our model focusses on the observational data
obtained by Herschel and Spitzer while we use archival photometry to complete
the spectral energy distribution. Results: The modelling shows that the object
is composed of a complex combination of several heating sources with different
spatial distribution. Our model uses a massive envelope with an mass infall
rate of 1.35 $\times 10^{-5}$ M$_{sun}$ yr$^{-1}$ to explain the continuum
emission in the (sub-)mm regime. At the same time we fit the CO and $^{13}$CO
ladders from 60 \textmu m to 650 \textmu m along with the two [\ion{O}{i}]
lines centered at 63.18 and 145.53 \textmu m. To explain the strong CO emission
at shorter wavelengths and the oxygen lines, we require a very warm disk due to
a high disk accretion rate reaching 6 $\times 10^{-4}$ M$_{sun}$ yr$^{-1}$ and
an additional UV field of 3\% of the overall emission to heat the disk.
