Steam not reaching 6th floor

bayridge

In a six story apt. House the top floor radiators only reach 170 degrees. This is a one pipe steam system. The sixth floor radiator air valves were all replaced with Hoffman "C" air valves. The basement steam horizontal risers are all insulated. There is master venting at the end of the risers. The boiler is set to 3 psi reaches 3 psi and turns off within 4 minutes. There are all gravity dry and wet returns.

EBEBRATT-Ed

How does the boiler rating compare to the heat output of the installed radiation?

Did this just stop working or has it always been a problem?

What controls the boiler a Heat Timer or a thermostat?

bayridge

the boiler is controlled by a heat timer platinum with heat sensors throughout the building. The heat timer achieves the desired average temp. Problem is the lower floors are in the 80s and the sixth floor only gets to 72.
When the boiler gets to 3 psi after a few minutes the automatic feeder is adding quite a bit of water. Then system cycles off. We're considering adding a boiler feed tank to maintain water levels better at 3 psi.

ethicalpaul

Any boiler close to properly sized for the radiation has contained within it enough water to do the job. This is my assertion.

Something else, probably insane piping, is causing the water to exit the boiler.

In a correct one pipe system, the water simply cannot get pushed out of the boiler by pressure.

Additionally, pressure does not prevent return of condensate (again, in a boiler that isn't insanely piped).

If you add a feed tank you will just have another thing to maintain and it won't solve your problem.

But all this is coming from a long way away with no eyes on your system. You need to call someone to your site who actually knows steam.

If you're in bay ridge brooklyn you have your choice of several great contractors, see the Find a Contractor page on this site.

dabrakeman

Shouldn't need 3psi ever. What are the size and length of your mains and what main vents do you have in place? Have you tried slowing down the lower floor radiators?

Jamie Hall

Well let's see. I suggest @JohnNY / He's in New York. Or maybe @clammy or @EzzyT /

In the meantime…

First, you don't need 3 psig. 2 psig is ample — and probably unneeded.

Second, you mention that the autofeeder feeds after it reaches the 3 psig. Where does that water go? If you are adding water on pretty much every cycle and the boiler isn't flooding, you have a leak somewhere — possibly a pretty big one.

Third, as noted by others above, pressure will not — cannot — cause water to back out of a properly piped boiler in any great quantity.

And last — a cycle of only a few minutes isn't going to heat all the radiation, even if the boiler is sized properly. Just not going to happen. Something else is amiss. Probably more than one thing.

You need boots on the ground who know what they are doing.

EBEBRATT-Ed

Could be shutting down on low water before the top floors get heated.

jumper

Every radiator supplied by riser or are there "branches" ?

bayridge

thank you for the comments. The building is total about 52k square feet. We are going to add more riser vents and lower to 2 psi and increase time boiler runs at 2 psi. The system is a converted old coal boiler system with perimeter piping in the basement all now insulated and still properly pitched to a now new 4 pass 100 hp, "best boiler". The system has a water meter and we are at about 170 gallons a day persistently everyday. The returns were all replaced with new copper all pitched towards the boiler. The returns are half above ground and half below ground. All insulated and new. The below ground portions are 1/2 dry and half wet. We don't have water hammer. We can get the building very warm but I'd like to lower floors 2-5 from 80-82 degrees to 72 and increase the 6th floor temp at the same time also to 72. We do suspect a small leak in the new returns that are underground but not much. We will address this in spring. For now we'd like to get the system more balanced with more heat on the top floor and less on the lower. As mentioned earlier we have been changing air vents with new. The 6th floor all has Hoffman C and the lower floors smaller. We have a temp clamp on the sixth floor radiator and it doesn't get above 170 ever. We run 60 minute cycles. But at 3 psi the boiler shuts down in a few minutes as heat timer is satisfied by the space heater average temp achieved. We have a heat timer platinum and about 30 space heat sensors in 5 entire lines of apts. So we have to heat to average of 78 degrees building wide to achieve 72 at the top floor. As mentioned we are adding water through automatic feeder when we are at 3 psi. I believe the water in the wet returns under the boiler waterline isn't getting to the boiler at that time plus evaporation plus the small leak. And yes if we continue to run at 3 psi the water in the boiler will be turbulent and trip the low water cut off although this isn't happening now. We have skimmed the boiler throughly and measured a 7 ph last time we added chemicals. Any more advise from the forum would greatly be appreciated. Thank you

bayridge

Also: the system does has risers and many branches all original to its 1924 original build. We are running on oil now and the burner is and IC burner MMG 42p Linkageless (siemens LMV52 ) Burner. I'm learning from these posts that we need to add more master vents and lower the psi to 2 and increase run time at 2 psi. And then see how we do with the over heating of floors 2-5. Thanks again for the advice.