Steam

[kurt]

I know what you're saying, and yes, of course, it's independent. If you're working in a lab.

Then there's the world, where one can put the most efficient system into a stupid box and it don't mean squat. So, breaking it down into academic discussion of combustion efficiency tells you a lot. Or nothing.

Having been a builder during the first energy crisis, we never talked about independence. All discussion was of interdependence.

I got an inefficient heating mechanical plant, a box that's not got a speck of insulation, and every other marker of inefficiency, yet it works wonderfully.

Explain that through combustion efficiency dynamics, because I can't.

[kurt]

There are no manufacturers guidelines; the building was constructed in 1929, and no one had yet heard of gas fired boilers. No one knows what the original "efficiency" of the coal fired behemoth was; I hope they don't care, as it has nothing to do with what I've been asking.

Arguing? I've been asking for explanations. Hoosier guy kind of gave an explanation. Lamb provided an idea for an explanation.

You're talking about everything other than what I've been asking about, with an undertone of insistence that you're "right". Yes, it's best you're not taking it any further.

Anyone else got ideas? Like I said, thermodynamics isn't my strong suit.

[Garet]

I got an inefficient heating mechanical plant, a box that's not got a speck of insulation, and every other marker of inefficiency, yet it works wonderfully.

In other words, the equation doesn't add up. It's time to ask yourself why. Either the equation is wrong, or one of your data is wrong.

Did you own the building prior to this year? Do you have a basis of comparison from before the changes? Did efficiency improve or did it always behave this way?

Have you 'clocked' the gas meter? IOW, watch the dials turn as the unit runs? Is the meter reading realistic?

[troylandlord]

It adds up, assuming the building is more or less rectangular, there is about an R value of 2 in the walls, and it has some insulation in the attic (R-20 for materials plus insulation). See this simplified heat loss worksheet (simplified meaning windows and doors are not considered because the walls are uninsulated to begin with, the heating season is simplified to 30 ASHRAE 1% design days for Chicago for a ball park load estimate, and natural gas is priced at $13/MMBtu which is about three times wholesale at a gas distribution hub in the US today):

http://aatcons.com/~diesel/heat_loss_kurt.xlsx

This also assumes the building is exposed to a temperature differential of 70 degrees on all four sides and the top for the heating season, if one or two of the sides of the building abuts another building, or if you actually use heating degree days for this facility you may get a lower loss and associated cost.

As to why the system heats so quickly, the thermodynamics in question are the thermal conductance of the iron in the radiators (which are good - the iron is conductive and the walls are fairly thin), the specific heat of the water vapor in the pipes (water vapor can carry relatively a lot of thermal energy per unit mass), and the thermosiphon effect that helps draw the water vapor through the pipes to the radiators. The boiler fires and may make a little steam internally, but once the the thermosiphon starts most of the material actually flowing through the pipes is hot water vapor. You have a very well balanced system, Kurt, so the optimal volume of water vapor for each radiator is flowing simultaneously, which is why the system doesn't make noise but does heat up quickly.

Finally, a lot of people don't really understand these systems and assume incorrectly the cast iron radiators are inefficient (they are not - see Kurt's narrative), or that simply increasing the boiler efficiency will have a huge impact on fuel consumption (it will not - again see Kurt's narrative on overall system efficiency). A $10K condensing boiler install is paid back in 20 years in Kurt's scenario if you plug a bump from 80% to 95% into the worksheet I linked above.

[hausdok]

Grrr,

Math. I thought we'd banned anything beyond second grade math from this site. [:-banghea

ONE TEAM - ONE FIGHT!!!

Mike

[kurt]

Garet, yes. The equation wasn't adding up, but I've tweezed out the variables. Gas meter is fine, records are accurate, thermostatic controls check out with my other equipment, etc., etc. Somehow, I'm gaining in ways I'm not familiar with.

Earl, that's great stuff.

The building is "exposed on all four sides; no adjacent buildings, all single family around me. The windows are reasonably nice single pane double hung; there's a few loose one's, but for a 1929 building I'd put the windows in a top percentile ranking.

The boiler is a basic WM LGB-6, with the secondary firing option so it's not all burners cranking all the time; it monitors condensate return temps and fires on some predetermined schedule depending on the condensate temps and the programming in the RD 1400.

Not a speck of insulation on any of the pipes, but you'd probably look at the pipe layout and say "oh, that's it. The main lines have secondary condensate returns at the big elbows, and the return loop is very well vented. From all I can learn, good function is about vents, and I got them.

I also wonder if all the "inefficient" pipe throughout the basement shedding heat.....if all that heat is captured in the concrete & terra cotta floor platform, and then slowly and evenly distributing it up through the building...(?).

The efficiency of the exchange is one of the mysteries, and the thermosiphoning effect you describe....I wasn't aware that was going on too. That would explain how quick the thing heats up but at the same time I'm not blowing steam out the vent.

I'm trying to grasp how moving the heat as vapor makes such a difference. I'm not a math guy; I think through problems mechanically, and this stuff isn't in my experience.

I'm starting to get a handle on it.

One very nice benefit of steam is the boiler room. It's cold here, and I go down there and pull my chair up to all that tonnage of hot iron, and it's real comfortable.

[Nolan Kienitz]

I'm starting to get a handle on it.

One very nice benefit of steam is the boiler room. It's cold here, and I go down there and pull my chair up to all that tonnage of hot iron, and it's real comfortable.

There you go ... warm/toasty. Get a card table, play some cards or dominoes and pour a glass of Makers Mark and you will be set.

Of course, once you open the Makers Mark ... Chad will be on your doorstep in a heartbeat. []

[mjr6550]

O

What are the conditions that allow an approximately 400 lb. chunk of cast iron to go from cold to really damn hot in 10-15 seconds?

Why does such a small change in vent size mean so much in performance?

Steam is an efficient way to transfer heat. That is why it is used in central steam loops. The heating of the radiators has to do with phase change. There is a large amount of energy transferred when water changes phases.

It could be that most of the one pipe systems I see have old vents that do not work well. Not much is maintained on many of these systems.

Another important issue with steam systems is boiler size. Unlike other systems, the boiler cannot be sized based on the heat loss of the building. It needs to be sized based on the surface area of the radiators. In my area this results in much larger boilers than would be used for hot water systems.

[kurt]

Get a card table, play some cards or dominoes and pour a glass of Makers Mark and you will be set.

Of course, once you open the Makers Mark ... Chad will be on your doorstep in a heartbeat. []

Yeah. I want to have a card game in the boiler room. "Don't come to the front door....come around back."

I happen to have a teeny bit of Pappy Van Winkle; I may break it out for the inaugural boiler room card game.

[kurt]

It could be that most of the one pipe systems I see have old vents that do not work well. Not much is maintained on many of these systems.

Nope, it isn't.

I'm now understanding that function is about venting. I knew it was previously, but I didn't realize how critically fundamental it is.

Bad vents, lousy performance.

[hoosier inspector]

The condensation of steam to water on the inside surface of the radiator moves massive amounts of heat, much more than conduction. If you size the vent properly it will utilize all the radiator surface with no waste.

That's what I'm trying to grasp. I can read the formula, but have no intuitive sense of what it means. Moving heat around as steam.....what's it mean?

Thermodynamics is not my strong suit.

Hot water boilers work on the principle of moving sensible heat. 1. Heat a material. 2. Move the material to the space calling for heat. 3. Let the material radiate the heat into the space. 4. Return the material and repeat. Steam boilers work on the principle of moving latent heat. 1. Add enough heat to water to change it's state into vapor. 2. Allow the vapor to condense onto a surface which releases all the latent heat of evaporation. 3. Return the water back to re-heat.

Click to Enlarge

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If you notice the 2 horizontal sections in the chart, these are the phase changes that suck up heat without raising the temperature. It takes 180 btu to raise 1# of water (about 1 pint) from 32degF to 212degF (freezing to boiling) but 970 btu (over 5 times as much) to change 1# of water to 1# of steam. Note the steam is still at 212 degrees, just in another state. All this heat is latent heat. It's the heat you get out of condensing steam, the heat recovered from flue gas in a high efficiency furnace, the heat removed from a condensing coil in an A/C unit. This is only a way to move heat around.This has nothing to do with efficiency of producing heat from fuel, and containing it in a structure.

[kurt]

Very, very helpful. Thank you .

And now, I can say this stuff back to my customers and they'll think I'm smart. [:-angel]