  We use the published Planck and SPT cluster catalogs and recently published
$y$-distortion maps to put strong observational limits on the contribution of
the fluctuating part of the $y$-type distortions to the $y$-distortion
monopole. Our bounds are $5.4\times 10^{-8} < \langle y\rangle < 2.2\times
10^{-6}$. Our upper bound is a factor of 6.8 stronger than the currently best
upper $95\%$ confidence limit from COBE-FIRAS of $\langle y\rangle <15\times
10^{-6}$. In the standard cosmology, large scale structure is the only source
of such distortions and our limits therefore constrain the baryonic physics
involved in the formation of the large scale structure. Our lower limit, from
the detected clusters in the Planck and SPT catalogs, also implies that a
Pixie-like experiment should detect the $y$-distortion monopole at
$>27$-$\sigma$. The biggest sources of uncertainty in our upper limit are the
monopole offsets between different HFI channel maps that we estimate to be
$<10^{-6}$.
