Steam Pressure & Leaks
Our ancient boiler finally bit the dust, so we hired Keyspan / National Grid to replace it with a Burnham IN6 gas-fired steam boiler, for our one-pipe steam heating system. We have a four-story townhouse. The original system & the radiators seemed to work fine without any troubles until now. For reference we used Size…
Our ancient boiler finally bit the dust, so we hired Keyspan / National Grid to replace it with a Burnham IN6 gas-fired steam boiler, for our one-pipe steam heating system. We have a four-story townhouse.
The original system & the radiators seemed to work fine without any troubles until now. For reference we used Size No 4’s air valves on the 1st floor, increasing to Size D on the top floor.
Three of our radiators have sprung leaks since the new boiler has been installed. They hiss & whistle and water burbles from the air valves, and now water is also leaking from the pipe-to-radiator connection as well.
So the installer reduced the pressure from 5 psi to 3 psi, but this hasn’t stopped the hissing and leaks. They said the radiators were not in their scope of work, and suggested that I should hire another plumber to correct the problem.
The manufacturer literature for Burnham cites numbers like 0.5 psi to 2 psi, so the 3 psi to 5 psi range that Keyspan used seems high. Could this be forcing steam out of the radiator pipes in unexpected ways? Am I even comparing correct numbers?
I am going to try replacing the air valves with new ones, but I need to know why the radiators might be leaking. Before I call in another plumber, any suggestions what may be going on?
Thanks Master Plumber.
(Correction: I meant to say we have really BIG radiators in the extension, otherwise the next size smaller boiler would have matched.)
Lower your pressuretrol main setting to 2 and the differential to 1.
That’s more pressure than you’ll ever need.
For update, Keyspan made good.
I called in the maintenance contract for service to check the boiler settings. In turn, they called the installer to come back and skim. No sloshing, clonking, no leaks today. Knock on wood.
Also, the pressure was adjusted from 3 psi to 2 psi, and I will watch out for cycle performance and check the farthest radiators over the next while. I am reading the Honeywell pressuretrol as 3 psi on the “main”, minus 1 psi for the cut-off? shown next to it, for the final subtractive differential of 2 psi.
For reference, for boiler sizing, the original proposal was based on a larger IN7 which was sized by the contractor from a rule-of-thumb table for no. of radiator units (e.g. Total 14 – 18 no. of radiators). I downsized the actual installation to the IN6 based on my own calculation after measuring each unit myself and looking up the tables for the radiator height & number of fins, etc for a total 375 SF of radiator for a 3,300 sf house. We have really radiators in our poorly insulated extension on the back of the house, otherwise the next smaller model would have worked. On the other hand, our R40 roof insulation doesn’t figure into this method of calculation at all.
If I’ve read the specs correctly, the Burnham Boiler Model steam ratings are:
Model IN5 358sf (Steam output 86,000 BTU)
Model IN6 450sf (Steam output 108,000 BTU I think)
Model IN7 542sf (Steam output 130,00 BTU)
Experts please feel free to jump in if there is disinformation here. Good luck to everyone on their heating projects, and stay warm!!!
btw… vicki… if you want me to come by and look at your situation for an initial free consultation, this is a service that i offer… you can contact me at errol832000@yahoo.con
Thank you, Master Plvmber. I will give you a ring when we are in contract.
Beating my usual drum, old boilers tend to be oversized (olden days: leaky single pane windows, less worry about energy cost, no insulation etc.)
For steam systems, the boiler size needs to match the ‘radiation’ or radiator capacity. So after a heat load calculation, which will probably wind up to be less than the old boiler size, a few radiators should be downsized (typically on the upper floors) to match the smaller boiler (that’s what I did on top 2 rads, which are half the size of the original and keep the rooms warm just fine.)
Yes, Mopar. My company replaces or installs from scratch around 70 boilers every year. We service or repair hundreds.
The right way to replace a boiler is to ignore what’s currently installed and put pen to paper to figure out exactly what’s needed in terms of heat output, venting requirements, efficiency and control options for that particular building.
Then the selected heat sources must be installed as directed by the manufacturer. Every boiler sold comes with a piping and wiring diagram that must be followed to ensure the intended efficiency and output values are realized.
Master Plvmber, what is the right way to replace an old boiler? In a few months, I will need to replace an old boiler in an old system (possibly over 100 years old) that was originally steam and then was converted to hot water. Do you do this kind of work?
Arches: No. The settings should remain if they work.