In the interests of accuracy I should point out that most CE certification is largely self-certification, and often to a surprising degree. You are even free to buy or download and print CE makings without hindrance or official interest. This is based on personal experience sinceI have organised CE marking for quite a number of things over several decades. It may come as a surprise to many that the 'Low Voltage Regulations' for example enable self-certification for any appliance operating at up to (from memory) 1200V. The only part of an E-cat heater system system as described that would not be covered by self-certification is any part pressurised at >0.5Bar.
Obtaining UL certification (where I presume UL is 'Underwriters Laboratory) is in contrast, I have been told, an expensive and highly formalised process