Italian to English Tech/Engineering Petroleum Eng/Sci Company registration data

I have included the full phrase in my question as I get the feeling one or two source words may be redundant in the target translation.

This list of oil company business activities includes items such as:

Trattamenti oli industriali
Vendita all’ingrosso e all dettaglio filtri aria olio, metano, carburanti
Vendita all’ingrosso e all dettaglio valvole per oli idraulici, diatermici, lubrfificanti
*Vendita all’ingrosso e all dettaglio ricambistica bruciatori per caldaie olio diatermico *

My attempt:

"spare parts for diathermic oil boilers" ??

(ps. I have used "heat replacement" to translate "Diatermico" everywhere else in my text, but I could not find anything with this term in the context of boilers)