There was a 10 year old boiler installed here on a Mouat vapor heating system. The key phrase in the last sentance was ''vapor heating system''. The boiler was not equipped with the proper controls to have it run in vapor. It was running at pounds of pressure instead of ounces of pressure. There was a faulty end of the steam main vent which wouldn't close when steam hit it. The vent would blow steam into the basement which would require the boiler to take on fresh water to replace the lost water. The extra pressure in the boiler would push the water up the return pipe and cause it to spill out the air vents. This lost water also had to be replaced. As time went on the extra oxygen in the fresh water ate holes in the boiler. This boiler died because of leaky air vents and the wrong operating pressure for the system it was installed on. We replaced the boiler with a Burnham boiler. All air vents were replaced and their venting rates increased as compared to what was there before. We also incorporated a digital water meter/feeder so water intake can be monitored.