  We used the CHARA Array to directly measure the angular diameter of HD 69830,
home to three Neptune mass planets and an asteroid belt. Our measurement of
0.674+/-0.014 milli-arcseconds for the limb-darkened angular diameter of this
star leads to a physical radius of R$_*$ = 0.9058$\pm$0.0190 R\sun and
luminosity of L* = 0.622+/-0.014 Lsun when combined with a fit to the spectral
energy distribution of the star. Placing these observed values on an
Hertzsprung-Russel (HR) diagram along with stellar evolution isochrones
produces an age of 10.6+/-4 Gyr and mass of 0.863$\pm$0.043 M\sun. We use
archival optical echelle spectra of HD 69830 along with an iterative spectral
fitting technique to measure the iron abundance ([Fe/H]=-0.04+/-0.03),
effective temperature (5385+/-44 K) and surface gravity (log g = 4.49+/-0.06).
We use these new values for the temperature and luminosity to calculate a more
precise age of 7.5+/-Gyr. Applying the values of stellar luminosity and radius
to recent models on the optimistic location of the habitable zone produces a
range of 0.61-1.44 AU; partially outside the orbit of the furthest known planet
(d) around HD 69830. Finally, we estimate the snow line at a distance of
1.95+/-0.19 AU, which is outside the orbit of all three planets and its
asteroid belt.
