It's a one year warranty, legally from date of sale but in practice from reasonable date of first operation. After talking to them directly the chances of causing any hidden damage if a qualified commercial welder does the work are slim - the risk is over heating the core and weakening the furnace braze joints at the core to header area. If a problem were to be totally unrelated to the weld area they would tend to honor their warranty, but there is a risk. PRC estimated the two way shipping at $60 plus the cost of the bracket at $15. I guess I'm cheap, but a $60 component warranty of nominal a year or less seems expensive to me, all things considered. Still thinking, but shipping a radiator back to Indiana, with the inherent risks of shipping damage, does not make an attractive option to me.