Welcome to the confusing world of Castolin and what are you actually getting when buying their silver solders.. After 47 years in this business nothing has changed!
It has not been uncommon for the same alloy to have different numbers dependent upon marketing conditions.
One of the links tells me that 1801 is cadmium free with a melting range 660 – 743 C but little else, This is more closely aligned to a 38% silver cadmium free alloy
The other tells me that it is 51% silver, 5% cadmium, 22% copper, 1% tin and 21% zinc which incidentally is nothing like the composition of easyflo 2.
Is it any good for boiler making ? Possibly.
If all the joints are being made on a small boiler using the same alloy – fine. Use it but in well ventilated areas because of the uncertainty about cadmium.
If you want to use two different alloys, ie step braze, then it falls between two stools. It is too high a temperature for the low temperature joints and too low a temperature for the high temperature joints!
If you have enough, I would suggest you scrap it and with the money buy alloy that you know and can trust. Contact John Betts Refiners Birmingham.
Keith