When my bride and I first moved into our home, we rented for the first eight years. There was a big oil-fired boiler that provided both domestic hot water and hot water heat - baseboard heat, not the old cast iron radiators I grew up with in Albany, New York (loved those). Aside from having the serviceman there once a year to replace the heating element, the only thing I ever had to replace was the circulation pump - a very large and heavy pump with a large, heavy electric motor. After eight years of renting we purchased the house. As it is with Murphy’s Law, “what can go wrong will go wrong,” we started having troubles with the burner. Replaced that and several years later while my wife was doing laundry, she noticed the floor was wet around the boiler. When the serviceman came and checked it out, he said the fire brick at the back of the boiler had cracked - due to a pinhole leak in one of the copper coils. That caused water to spray onto the hot brick, thus cracking it. Of course the water continued to spray out from the hole, found its way to the outside and onto the floor. Time for a new boiler!
After going through all the specs with the serviceman to determine the size of the new boiler, I decided to go with the next size up. My thought was that it had larger heating coils (for domestic hot water and heat) and wouldn’t be turning on and off so often. My wife and I were glad we went for the bigger boiler as several years later she wanted to move her mother up here from Florida. We decided to build a 500 square foot addition (2-story, 500 sq’ each). Had the serviceman come down to see about heating it. He gave us the good news that the boiler we had installed a few years earlier was more than enough to add another zone to. Yeah! We’ve been quite happy with this boiler as the only thing we have had to do was the annual maintenance (change the fuel filter and heating element). This boiler is a McGreggor (sp?) and we are happy with it. And it’s so much more energy efficient than that old clunker the house came with.