UPDATE: I am trying to respond to each person that took the time to answer, thank you! The system will not let me...so here's the deal. We don't know if the company where we purchased the heater will honor an exchange..if it does, then we won't have an issue with proceeding with the electrical work while waiting for the correct heater to be in stock. I was asking because I specifically asked the GC what type of heater back in September, I asked again in November and both times, I sent her the specs of the heater. It is not right that she waited all these months to now tell us the heater is too big for the panel per the plans and to let us know if we wanted to upgrade the panel it'll be an additional almost $1k. It will involve the architect writing up the revision and then submitting to the City for approval. I can almost bet that she did not answer me in Sept or Nov bc this is her way of getting more money. Why else would she not have responded back then and let us know everything she's told us now? It's Like we really have no choice, especially if the heater people will not exchange the heater!! That's why I feel like this is her error. She is the GC and should have been able to tell us this crucial info and verified the specs back in Sept and not just told us to buy any heater we liked!