Hello - looking for some advice on the boiler in our home. We are first time homeowners, purchased our house a few months back, and are trying to use the boiler for the first time. I have always had a furnace, so I have no experience or knowledge of boilers. The boiler itself is a 1971 Pennco, Series 15, original to the home. The pumps are Bell & Gossett, Series #100 - I believe they were installed w/in the last 15 years maybe. It's 3 zones (second floor, first floor, basement) w/ 2 pumps, the 1st and 2nd floors running off one. Being my first time using it, I called an HVAC company to inspect, etc. The guy came out and was looking, and put a carbon monoxide detector on the unit, while he turned it on and inspected. After about 10 or so minutes, his detector was going off, and he told me he by law he needed to shut it down, and that we needed a new boiler, which he quoted me for, to replace the whole thing. (I have a CO detector in the basement across the room that was not going off) The home came w/ a home warranty, so I had their vendor come out and look at it, and the guy basically said it was fine, and that the detector only went off b/c the inspector had it right next to the unit, and that he was probably just trying to make a sale. I am uncertain what to do here, but obviously want to make my decision before it really starts to turn cold. While I definitely don't want to take any risk w/ CO, I'm also not crazy about spending thousands of dollars. So my questions are: -Is it normal for CO to be present right around the boiler itself? I believe his meter showed '49'. -How long should it take for the baseboards to heat up on the second floor? (2400sqft house, had it on for over 30min, and the upstairs baseboards did not heat up) -Safety issues aside - am I wasting money by using a 45 year old boiler? Is it beneficial to replace with a new boiler? And if so, worth getting a high efficiency one, or will a standard model work just fine? I have to assume either will be better than the model I have now, just not sure how big a difference. Sorry for the long post - any help/advice/insight is appreciated!!!