Gas Supply for Boiler
One of the long term projects in our building is looking at a replacement for aging (but still functioning) oil-fired boiler for steam heat – potentially with a gas-fired or dual-fuel boiler. Currently, gas is supplied from the street via two seperate 2″ pipes and used for for all (25) stoves and a 2 or…
One of the long term projects in our building is looking at a replacement for aging (but still functioning) oil-fired boiler for steam heat – potentially with a gas-fired or dual-fuel boiler.
Currently, gas is supplied from the street via two seperate 2″ pipes and used for for all (25) stoves and a 2 or 3 gas clothes dryers in the building.
Is there any rough guideline for piping requirement for a gas-fired boiler? Our current unit is rated at 1,400,000 BTU/hr, but is probably oversized (based on EDR of our radiators).
Is gas line capacity something that a plumber tests? Or is this a Keyspan issue? Is it safe to assume that increasing supply can only be achieved by digging up the sidewalk and installing larger supply mains to the building?
Thanks, SteamMan…you’re right, I neglected to include a pickup factor, so I guess the 550,000 becomes 730,000 – 825,000 depending on the factor (the steam mains are uninsulated, but won’t be for long).
Plus, I imagine its the boiler output that has to match the EDR, so the input would be higher to account for the boiler inefficiencies. Assuming 83% efficiency, now the boiler need is 901,000 – 1,018,000 BTU.
As you noted, I’m not actually planning on buying a boiler based on these calcs…I was just trying to figure out the feasiblity of installing one with existing gas supply – which, sadly, seems unlikely now.
Arches,
Please be careful sizing your boiler as it isn’t as straight forward as counting radiators calculating the EDR from them. Know what a pick-up factor is and what goes into it. Get out of the boiler room and look at all the piping around the boiler. Understand the insulating characteristics of your building.
I am not trying to be condescending, only trying to help you size the boiler with proper considerations. Obviously your installer will size it for you but knowing what goes into it will help you to not only make a more informed decision but also a better estimate.
It REALLY sucks when the brand new boiler is too small!
Thanks guys. I took a closer look at it last night, and for whatever reason, one of the mains supplies 20 units in the building, while the other only supplies 5 units.
My EDR calculation shows that the boiler only needs to be 550,000 BTU (plus some additional amount for DHW, i suppose). Assuming the 5 units only draw a max of 250,000 BTU for cooking gas, maybe that 2″/1,000,000 BTU supply would be enough, afterall. Lots of assumptions, I know.
larger main will be required to increase load
Generally, a 2″ gas line is used to carry 1,000,000 BTUs.