olemus
ruumide või seadmete soojendamise süsteem
=
a system that provides heat to a building, a number of buildings or an equipment

ülevaateid
https://en.wikipedia.org/wiki/Heating_system

näiteid
https://en.wikipedia.org/wiki/Electric_heating

https://en.wikipedia.org/wiki/Central_heating

https://www.energy.gov/sites/prod/files/2015/02/f19/QTR%20Ch8%20-%20Process%20Heating%20TA%20Feb-13-2015.pdf