The material used for these kind of steamers should be very heavy kind of plastic or even stainless steal. This is an important feature to look at because the steam being emitted from the steam cleaner would be of very high temperatures. Therefore, if the outer housing is made from weak plastic or sheet metal, then the chances are that the cleaner would break easily and basically have a much shorter life span.
The next feature you should inspect closely is the heating mechanism or the heating rod being used in the steamer. The heating rod is used to heat the water in the boiler to produce steam. It is important that your heating rod is easily removable from the boiler so that if it breaks or malfunctions you can easily buy a replacement without having to replace the whole boiler.
This will save you time, energy and of course money which is something we all try to save! In order to buy commercial steam cleaners that do not “suck” it is important that you buy a steamer that has an excellent warranty like the ones found here: https://www.daimer.com/commercial-steam-cleaner/. Buy from a well known and reputable company that will offer you support for your machine as well as a warranty which is at least 5+ years. It is also ideal that the company offers a separate warranty on the boiler especially if it is particularly costly.