I had Meyers hvac come out to check my furnace for a second opinion. Another company via Home Depot had been out and tried to scare us with claims of carbon monoxide leaks. I was very suspicious because we recently had a full home inspection prior to purchasing the house and all was good. Only notation was that it was an old unit.
Meyers did not find a leak but noted maintenance issues. There was no pressure to replace all the old systems though they gave me a detailed proposal which I will probably agree to in the near future.