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The importance of the radiative feedback from SMBHs at the centers ofelliptical galaxies is not in doubt, given the well established relations amongelectromagnetic output, black hole mass and galaxy optical luminosity. Inaddition, feedback due to mechanical and thermal deposition of energy from jetsand winds emitted by the accretion disk around the central SMBH is alsoexpected to occur. In this paper we improve and extend the accretion andfeedback physics explored in our previous papers to include also a physicallymotivated mechanical feedback. We study the evolution of an isolated ellipticalgalaxy with the aid of a high-resolution 1-D hydrodynamical code, where thecooling and heating functions include photoionization and Compton effects, andrestricting to models which include only radiative or only mechanical feedback.We confirm that for Eddington ratios above 0.01 both the accretion andradiative output are forced by feedback effects to be in burst mode, so thatstrong intermittencies are expected at early times, while at low redshift theexplored models are characterized by smooth, very sub-Eddington mass accretionrates punctuated by rare outbursts. However, the explored models always failsome observational tests. If we assume the high mechanical efficiency of10^{-2.3}, we find that most of the gas is ejected from the galaxy, theresulting X-ray luminosity is far less than is typically observed and littleSMBH growth occurs. But models with low enough mechanical efficiency toaccomodate satisfactory SMBH growth tend to allow too strong cooling flows andleave galaxies at z=0 with E+A spectra more frequently than is observed. Weconclude that both types of feedback are required. Models with combinedfeedback are explored in a forthcoming paper [abridged]

Feedback from central black holes in elliptical galaxies. I: models with either radiative or mechanical feedback but not both