  A recent measurement of the dielectronic recombination (DR) of W^20+
[Schippers et al Phys. Rev. A83, 012711 (2011)] found an exceptionally large
contribution from near threshold resonances (<1eV). This still affected the
Maxwellian rate coefficient at much higher temperatures. The experimental
result was found to be a factor 4 or more than that currently in use in the
100-300eV range which is of relevance for modeling magnetic fusion plasmas. We
have carried-out DR calculations with AUTOSTRUCTURE which include all
significant single electron promotions. Our intermediate coupling (IC) results
are more than a factor of 4 larger than our LS-coupling ones at 1eV but still
lie a factor 3 below experiment here. If we assume complete (chaotic) mixing of
near-threshold autoionizing states then our results come into agreement (to
within 20%) with experiment below about 2eV. Our total IC Maxwellian rate
coefficients are 50-30% smaller than those based-on experiment over 100-300eV.
