Our installations come with a CO detector interlocked with the boiler. This is extremely important as the boiler will shut down if CO is detected. About 2 years ago we installed a boiler in a loft in Manhattan (apartment 5R). As a precaution we installed two CO detectors, one inside the boiler room and one outside the boiler room. There were also 2 CO detectors installed in the loft as additional precaution by the owner.
Recently the tenant in the apartment claimed that the CO detector outside of the boiler room had been going off and he was very worried that the system was producing dangerous levels of CO. We came out and checked our heating system and didn't find any evidence of CO in the boiler room. A few weeks later, the CO detector went off again. This time he became very nervous and moved out of the space until the issue was resolved. The apartment owner purchased a CO monitoring device which records levels of CO and keeps the highest one in memory. On a warm day when our system was not operating and the tenant was not in the space using hot water, the CO levels reach 89. The owner of the property called in a very knowledgeable building investigator who went through our system and all the systems in the condo building. What they found was extremely disturbing.
Below is an excerpt from their report:
"After thorough examination of apartment 5R's heating system, a high efficiency condensing hot water boiler with a tankless domestic hot water component. This system has a carbon monoxide detector in the equipment room. The system was found to be in good operating condition, there were no observable signs of combustion gas leakage.
... The first issues I observed was that the direct vent gas boiler for apartment 3R boiler has a cracked exhaust vent, this is leaking combustion gases into the building and is a source of the carbon monoxide. "
The report also found that every other boiler in the building was being vented illegally and incorrectly.
"With the use of a smoke stick, I found that the combustion gases were being blown back into both the apartments for both apartments 3R and 4R. These water heaters were not installed as per manufacturer's instruction or per New York City code..."
The only reason that any of this was found out was because we had installed CO detectors as part of our installation. This instance goes to show that you can do everything right and still get into an issue because of someone else's incompetence. Buildings are required to have smoke alarms as well as CO detectors installed, yet very few of them do. The residents of this building were very fortunate to have this issue found out before any casualties occurred.