Will a 30amp 2-pole contact relay work in the place of a 25 amp 1-pole contact relay? Both have 24 volt coils.

I need to understand this a little more... are you replacing the breaker for your A/C or funace? Your A/C should already be on a double pole breaker... Your furnace however would be on a single 25... could you clarify a bit more? Thank you.