Old, low-efficiency heating systems. With ge’s boilers, our customers can burn a wide spectrum of fuels, from high-rank coals to low-rank coal wastes, and from oil and natural gas to opportunity fuels such as petroleum coke, biomass and oil shale. Regular maintenance and servicing is a wise precaution, we can ensure that your current system is operating to peak performance, ensure against carbon monoxide leaks and prolong its lifespan. How to buy the best baby carrier or baby sling. Boilers that.