Customer is getting co reading of 200 ppm around this tapping at the top of an old american standard hot water boiler, he said it had a meter in it before they swapped from oil to gas. MassSave thought the CO was coming out of the hole, I think the top cleanouts on this boiler may need to be sealed with furnace cement, any thoughts?
on to something. Is that a burn mark on the side of the jacket? I would at least pull the top off and look for signs of leakage. Hard to tell from pic what the tapping is for. Is it suppose to be for air vent/steel exp tank?
If I remember correctly, the high limit was usually mounted on top, and reverse aquastat ( or maybe operating) was mounted in coil on rear. Probably leaking between sections and and exiting thru opening. That boiler will probably last another 50 years,but a new boiler will be much more efficient.
Looks like the tankless coil was taken out of service, and the control removed. That burn mark is nothing to worry about. That is an Amercan Standard Arcoliner wet base cast iron boiler. It is not efficient, and good idea to replace it, but it will outlive whatever you install in it's place.