My Weil-McLean oil boiler/burner has a tankless coil for the domestic hot water.
Question - I had a new guy clean my coil when the hot water lessened. This is only the second cleaning in its 14 years and it is the original coil - I am a one-person house. He seems to do nothing but this - his truck says "(his name)'s Coil Cleaning" on the side. He said I should do it every year or two to keep the water hot but also to keep minerals from causing pin holes in the coil and its leaking. However, someone else said the frequent cleaning of the coil with chemicals is what causes pin holes. Who is right?
Also, my domestic water gets "sticky" after a while. Is that due to minerals?