  We present the first far-IR observations of the solar-type stars delta Pav,
HR 8501, 51 Peg and zeta^2 Ret, taken within the context of the DUNES Herschel
Open Time Key Programme (OTKP). This project uses the PACS and SPIRE
instruments with the objective of studying infrared excesses due to exo-Kuiper
belts around nearby solar-type stars. The observed 100 um fluxes from delta
Pav, HR 8501, and 51 Peg agree with the predicted photospheric fluxes,
excluding debris disks brighter than Ldust/Lstar ~ 5 x 10^-7 (1 sigma level)
around those stars. A flattened, disk-like structure with a semi-major axis of
~ 100 AU in size is detected around zeta^2 Ret. The resolved structure suggests
the presence of an eccentric dust ring, which we interpret as an exo-Kuiper
belt with Ldust/Lstar ~ 10^-5.
