Steam Radiators

Dan Foley

Nice story, Dan

https://www.bloomberg.com/news/articles/2020-08-05/the-curious-history-of-steam-heat-and-pandemics

DanHolohan

Thanks. Patrick Sisson, the report, was excellent. 

ChicagoCooperator

Congrats, Dan!

I'm wondering when that practice died out? As far as I can tell, my building, which was designed in 26/27 had the heating pretty much right sized w/o windows open.

DanHolohan

I sense the practice died out during the Great  Depression when fewer people had money to pay the coal bills. 

motoguy128

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ChicagoCooperator said:

Congrats, Dan!

I'm wondering when that practice died out? As far as I can tell, my building, which was designed in 26/27 had the heating pretty much right sized w/o windows open.

It’s also possible they realized that at design conditions there’s enough air leakage anyway and it only lasts for a few hours a day.

Realistically there was still likely enough reserve capacity for a few windows cracked open a little regardless. Older buildings often had a lot of mass with brick and concrete or stone and need less peak capacity that design might indicate.

The Steam Whisperer

I have found that in Chicago, most of the steam radiators were still oversized all the way up to WWII. In two pipe steam I nearly always size orifice plates to 60% the EDR of the radiator at design pressure for the design day. This typically results in nearly halving the size of the boiler necessary for the building. Prior to about 1900 to 1910, the radiators are much smaller. I do occasionally come across some mid 20's to 40's buildings where they seemed to size radiators much closer to load. This seems to be mostly convector systems built into walls.

Almost everything in Chicago is high mass construction, so having an "undersized" system, tends to not be a problem since the building mass prevents the full effect of low overnight temperatures from ever reaching the inside. Heat movement through concrete is about 4 inches every 24 hours, so cold nights are easily buffered by warmer days. I've always sized closer to the edge of design day loads for masonry buildings.

PMJ

I think coal fired steam systems had to have been designed with radiation a very significant portion of which was understood would never see steam. I don't see how the very sensitive pressure draft controls could have operated properly if the system ever filled. I think the design had both boiler and radiators operating comfortably in the middle of their actual capacities on design day. I think it is a mistake to assume that the dead men ever viewed the radiation they installed as ever going to be full of steam.

The coal fired boiler never could be run at "maximum" fire with respect to what the physical machine was actually capable of. Today, our intermittent fire machines ONLY run on that maximum. So, sizing a replacement boiler to replace the coal fired one by its max rating OR sizing one to be able to fill installed early 1900's radiation will always result in significantly more boiler than is actually needed.

motoguy128

Mass is definitely under appreciated. MY brick Victorian is I think 4 courses of brick in total including face brick. I find is takes a full 3 days to fully respond to a weather change. The attic heat has an acute effect due to solar gain, but the convective gain is very slow. It went from highs in the low 90’s to a couple 70f days and my AC was still running a fair amount when it was 55F in the AM, trying to cool the brick off.

I;ve actually adjusted my schedules and overcool with my downstairs system In the morning when it’s coolest outside before the sun hits. I have stage delays set at 2 hours so it runs on low stage as well.

We’ve sized system for a new construction recently and my boss was nervous that it only came out to 2 tons where he normally would install 2.5 or 3. I reminded him of all the shade trees all around the house, the high attic, high ceilings (beneficial stratification) and the walk out basement for extra mass which appears to have an insulated slab.

The Steam Whisperer

We’ve sized system for a new construction recently and my boss was nervous that it only came out to 2 tons where he normally would install 2.5 or 3. I reminded him of all the shade trees all around the house, the high attic, high ceilings (beneficial stratification) and the walk out basement for extra mass which appears to have an insulated slab.

Oversized cooling is about as prevalent as oversized steam boilers. In my previous all frame home of 3200 sq of floor area in Northern, IL, about 1400 up and the rest on the first floor, we cooled the home with a 1 1/2 tons of window air conditioners. Dark green aluminum siding, huge but partially shaded south and east windows ( not much west), r-19 walls and r- 26 ceiling. Maybe during multiple days of upper 90's we may have needed another 1/2 ton. I know any A/C contractor would have tried to sell us at least a 4 ton to 5 ton central air unit.
Of course window units tend to provide more usable btu's/ ton of cooling since the don't have to cool a big blower motor operating inside the home. Our current 1500 sq ft one story in Chicago with single wythe brick veneer stays at 75 interior or below in the hottest weather with only a 1 ton window A/C. It will be better when I get all the interior windows back in ( storms only for several windows).
I had the same experience with cooling our previous church. Contractors wanted to install between 12 and 15 tons of cooling. I did a detailed calc on the space ( tall ceilings, very high mass, and 2 to 4 hour occupancy) and ended up with 6 tons, which is what was installed and works fine ( it would work better if they staged the 3 units to get rid of theh cold and clammy feel until the space fills with heat from the people)

ChicagoCooperator

Thanks for the responses. We have convectors and were originally oil fired rather than coal. It wasn't sufficient (or the system wasn't run right) in numerous places - lots of add on radiators or convectors replaced with radiators.