Experimental results are presented on silica deposition in a typical domestic heat exchanger during combustion of siloxane-containing gas as a model of biogas that is produced naturally during the anaerobic degradation of organic material in landfills and waste water treatment plants. A model of silica deposition is developed. The main objective is to demonstrate that the mass flux of silica to heat exchanger surfaces is not sensitive to details of particle coagulation process and particle size distribution. It is shown that the deposition flux of silica depends linearly on siloxane concentration in input air/gas mixture. (C) 2013 Elsevier Ltd. All rights reserved.