RM Cylinders RM Cylinders has been manufactured from the ground up to provide storage capacities beyond thier regular product line while maintaining the core cylinder the same. RM Cylinders Stelflow’s are manufactured to fit domestic and commercial duties, the cylinder proves versatile for an array of situations where there is a call for large stores of Unvented Hot Water. The installation process are no different meaning simple and hassle free installation. As well as this, RM Cylinders have continued their customer commitment and the product lines comes complete with a 5-year guarantee, enabling long trouble-free service and hot water for many years to come.