Abstract: An air-fuel ratio programmable control method for a fuel burner installation, and a fuel burner installation adapted to operate by the control method. In the method, an error (Ep) is determined by subtraction of an input (Po) representative of the existing firing rate and an input (Pn) representative of the required firing rate; depending on whether Ep is positive or negative, fuel and air supplies to the burner are modulated in either air-led or fuel-led manner, respectively, to set the firing rate to the desired value (Pn); in addition, the error (Ep) is compared to a predetermined breakpoint (Xp) so that if Ep exceeds Xp fuel and air supplies to the burner can be modulated simultaneously for fast control action.

Abstract: A solar heat utilized air-conditioning system comprising: a solar heat collecting unit for producing warm water by heating a circulating heating medium water by solar heat obtained by collector plates disposed in parallel with each other; an absorption type refrigerating machine for producing cold water by provoking a refrigerating cycle, using the warm water produced by said solar heat collecting unit as the heat source for a generator; a main heat exchanger which indirectly heat-exchanges an intake fresh-air for a circulating cold or warm water in an air-conditioning unit disposed on the way of a fresh-air intake path to a space to be air-conditioned, thereby to produce cooling or heating air; an air-cooling and heating apparatus capable of selectively supplying the circulating cold or warm water to said main heat exchanger; and an auxiliary heat exchanger capable of selectively flowing either warm water produced by said solar heat collecting unit or cold water produced by said absorption type refrigerating