oil and gas appliances in same masonry chimney

kev

Where can i find the code for NY state that allows or does not allow, a gas fired natural draft water heater and a oil fired boiler to share a common chimney in the same mechanical room. Thanks for any help. 

Bob Harper

NFPA 211

I don't know if NFPA 211 is referenced in any of the codes that apply in your area but it is the national standard for chimneys, fireplaces, vents and solid fuel burning appliance. It is referenced, for instance, by the International Building Code for heater flues and combustion venting other than fireplaces.



211 allows common venting of oil and gas IF:

-The common vent or chimney is sized for both appliances combined

-the common vent or chimney passes a Level II inspection, which will determine the suitability of that chimney serving both appliances.

-both appliances are equipped with "primary safety controls".



Now, it is up to your local code official (Authority Having Jurisdiction) to rule on what he will accept as primary safety controls. This generally means some device to shut off the fuel supply if the flame goes out so fuel does not continue filling the combustion chamber making it into a bomb. Another version of primary safety control is generally considered a flame proving system such as a spill switch on the vent system to safeguard against backdrafting.

kev

thanks

I located the correct paragraph ( after going by it ten times) in the FUEL GAS CODE that  is similar to the NFPA code. Thanks again.

LIBob51

Masonry/clay Chimney

Clay chimney liners were made for the venting of oil fired equipment. Oil burns between 1300 and 1700 degrees Fahrenheit, while Natural Gas burns between 700 and 900 degrees. The lower flue gas temperatures of Natural Gas tend to condense inside a clay liner, which causes the liner to collapse. I live on Long Island and work here and in the city, and most town codes are now requiring the installation of a stainless steel chimney liner with gas equipment.