Old house, steam heat, new boiler - still takes 1hr15min to heat all radiators...

Jamie Hall

The question of whether the air in the dry return needs to be factored in is an interesting one -- but it can be solved logically.

First, in a two pipe system (not what we are talking, but just to make the answer complete), the dry returns must be vented, as the radiators vent into the dry returns and often then mains do as well.

That said, however, the only air we need to worry about is the volume of air between the boiler and the radiators, and the air in the radiators themselves. Therefore, the only air volume we need to vent is the air in mains and the radiators -- not the air in any returns. The air in the mains should be vented by vents at or very near the ends of the mains. These should be fairly large, and should be arranged so that to the extent possible steam arrives at the end of each main (if there is more than one) at more or less the same time. The radiator vents need to cope with the air in the runouts and risers (which can be substantial) and the air in the radiators. If the radiators are perfectly balanced to the space, again, the sizes should be such that the radiators heat equally. Sometimes it is necessary to place a smaller vent on certain radiators, however, if they are too large for the space. It is also sometimes necessary to place vents on some of the runouts or risers, if they are long -- but it could be argued with some logic that in that case these are much more like sub mains than they are like runouts or risers, and should be considered as mains.

mickeylewis123

Hmmmm. Now you're really got me wondering. I think I read somewhere in this blog that there are 1-pipe steam systems that don't have main vents - that they vented via the radiators exclusively. I'm wondering if my original piping was designed not to have main vents? I just listened to Dan Holohan's Youtube video "The Lost Art of Steam Heating" and at one point he mentions how we should listen to the dead men - they knew what they were doing and designed in specific ways - we don't always know better today. I have 3 mains coming from my boiler. None of them had main vents at the ends of the mains. But I did have Gorton G1's at the end of the condensate returns on the two longest mains - but they may not have been original? Any thoughts?

Fred

When the old coal fired boilers were installed, they were fired from the start of the season through until the end of the season. They basically simmered all winter. A nice slow steam flow. Once the initial air was out of the mains and radiators, there was not a need to evacuate air out, repeatedly and every hour like todays gas/oil fired boilers require. Dead men certainly knew what they were doing but they could not have possibly know how today's systems would cycle on and off, virtually 24 times a day. Venting on a one pipe is essential to save on fuel costs and get a responsive, even temp thoutghout the structure.

mickeylewis123

I sit in my office day after day. There is a smallish radiator in the office - about 20" high, 9 sections - whenever the heat is on, it is the slowest radiator in the house to heat up - and it makes a constant noise, not banging, hot hissing, but like a gurgling, not in the radiator, but more from the pipe and the valve to the radiator. It just stopped, the vent hissed a little bit, and it went quiet. Any ideas as to what it might be?

Fred

Either the valve isn't fully open or the horizontal pipe under the floor is not pitched back to the main or the pressure is still too high and the condensate just can't, get back to the boiler until the end of the heating cycle. Did you clean the pigtail under the Pressuretrol? set the Pressuretrol to .5 Cut-in and "1" differential for a Cut-out of 1.5 PSI? Check the pitch on the horizontal pipe that feeds that rad?

mickeylewis123

i think you might be right on the pitch of the main. the take-off comes out of the header and angles up to the ceiling, then turns and goes level with the ceiling. Should the main be pitched away from the boiler? I think it is either level, or slightly pitched back towards the boiler. It's hard to determine the level since it's insulated.

Fred

The radiator run-out should pitch towards the main and the main, in that area should have some pitch in the direction the rest of the main pitches. Level or opposite direction will cause problems unless there is a drip leg, that drops to a wet return, in that area.

vibert_c

@miskeylewis123 Congratulations you are learning quickly. Here is a snip from you first post in this thread.

I'm doing as much reading as I can, and attacking this systematically, but a little frustrated that I haven't made any real progress.

I started by checking the basics - all radiators level, all radiator valves completely opened, all radiator vents are in good shape - mostly new, boiler recently serviced for the season.

Page 80 in "Lost Art of Steam Heating" says "One Pipe Steam - A Matter of Detail" Well the "dead men" never set your emitters level. Why did no one who scanned your first post not pick up on this important piece of information that you supplied?

I miss "@Icesailor" He taught me a lot.