Just had 2-3" hail storm. Roof totaled and furnace vent cap destroyed. Had heavy rain and hail coming in from damaged furnace vent. Can this cause damage to 40 year old furnace? Had HVAC company come out and he detected CO leaks in multiple places and said need new furnace. Just had furnace inspected 1.5 yrs ago and was fine. Insurance adjuster rejected claim. Thanks!

Did the hail reach that part of the furnace or was it still protected by the sheet metal ?

40 year old furnace is old. Anything could happen in a year. If the efficiency was in range when inspected during a quick routine test, I'm wondering if leaks were just starting anyway, or about to. Bet the company that just looked at it needs summer work, plus sees insurance dollars dancing around. Insurance company is bound to deny the claim anyway, based on age of furnace and failure to tie this to hail and rain. So who knows? I'm no expert on HVAC. I just know people. Get another opinion, and ask for details, and ask them to show you.