District heating in Russia

DanHolohan

have knowledge of the district heating systems in Russia?

Steamhead

I read somewhere

they have a district hot-water system in Moscow, but that's all I know..........

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DaveC

I have many Russian co-workers here...

Any specific questions that I can relay to them?

DanHolohan

That's what I thought

but I have a friend who's telling me that it's steam. I've searched the WWW and come up with mixed answers. I suspect it may be a combination of both (heat exchangers). It's been around since the 1920s, which makes me wonder.

So much to learn.

DanHolohan

Thanks, Jim.

I'm curious as to whether it's steam or hot water, or a combination of both. Also, anything they can share about the piping systems, and the size of the systems. Thanks.

DaveC

Got this so far...

The heating plant is a single boiler, usually oil-fired, in a garage type of structure. It supplies hot water through a continuous circulation system underground. Cast iron radiators are in the buildings, which are goverment owned. There is no thermostat in the buildings, but the rooms never get warm enough, anyway. Once in a while it is chilly outside over there ;^)

bert

Kiev

I was involved in exporting B&G pumps to so called modernize a large gravity system in several 8 story buildings about 20 years ago. I vaguely remember it had
8" and 10" risers in the system, but didn't really work well.

What I do remember clearly was that the $ came from one of our good old USA programs, in other words, we all paid for
a little of it.

DanHolohan

Did you hear of

any steam? Thanks.

Dan Peel

Copy cat systems

In northern China, right next door to Russia, all I saw was district hot water primarily produced as a byproduct of coal fired electric generating stations. The building I was staying in was being refitted to include isolation shutoffs. Apparently with the adoption of freer market trading the state now charges for heat but had no way of shutting down individual apartments for non payment - only complete buildings. Enjoy.....Dan

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DaveC

No steam recalled...

wouldn't the condensate return lines be prone to freezing? And you would have to supply the steam through horizontal runs for a few blocks - that doesn't sound feasible, does it?

Weezbo

our Next door neighbours:)

If like us they have steam and 210 ?atilde;F continiously circing glycol. This is my best guess.downloaded heat from power plant.... and dedicated steam for specific buildings or purposes... JUst called me electrical aprentise going Betern most journeymen an lad ssays the guess is good. they have bothe but mainly cirulating water no t stats,controls at building,if like us they have flow meter cicr seter sibie with X changer in meck room... Lads from Russia.My nearest neighbour:)Oh he says control is piss poor ...and that the new and remodels have radiant slab and staple up the rest have CIrads..with more of a say Boom HEATearly and late winter.. no (LOW) heat cold controls must be marginal at best.outside injection temp must be the new order of the day.

DanHolohan

With district steam

they waste the condensate, Jim. In NYC, for instance, they'll cool it with a heat exhanger, preheating the domestic cold water, and then dump it. It runs through a condensate meter first, and that's how Con Ed charges.

ConEd runs horizontal mains for many miles. Not a problem as long as the condensate is handled properly.

Jack_21

Klamath Falls OR

Not in Russia, but Check out the Geo-Heat Center, at OR Inst Tech. They do it with geothermal deposits. using a hairpin, downhole HX. Great application.

Clif Heeney_2

District Heating in Estonia

Dan,

I live in Tallinn, Estonia. Estonia was formerly a part of the USSR, so I believe that the heating systems that we have here are probably basically the same system as in Russia today. We have district heating serving probably half the city, which is 435,000 people. As far as I know the boilers are all fired with oil and only make hot water, which is then piped into the district that that particular plant serves. There is a power-generating plant on the outskirts of the city, which of course utilizes steam to fire the generator. I believe that they then use the steam through a heat exchanger to make hot water for the district heating in that particular area of Tallinn.

Each building has a meter and pays for the amount of hot water that is used. Some of the apartment buildings that have been renovated have also placed individual meters in each apartment so that the bill can be divided evenly. Without the individual meters, then the apartment owners pay a percentage based upon the size in square meters of their apartment.

The temperature of the hot water produced by the district heating plants is based upon the outside air temperature. So just imagine a giant sized outdoor reset!

Sorry that I can't answer your question about Russia though. My wife's favorite aunt lives in Moscow, we'll send her an email tomorrow and see what she can find out for you!

DanHolohan

That's so helpful, Clif.

Thanks. And thanks to your aunt.

Were you born in Estonia?

leo g_13

WOW!!!!

the world is truely turning into a village! I am feeling the same feeling right now that I use to get as a child trying to think about eternity!

Clif, do you have any pictures?

Leo G

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\"Maine\" doug

I know of one in Canada though

My parents lived in a company house that was heated with water from a central plant using electric boilers. It was scary as a kid to go into the plant with these huge transformers humming and pumps running. In another town, the mill sent steam to the company houses and in my Uncle's place, there was a little metal ring on the floor in the front hall with a small hole in it, almost like an escutchon (sp). Steam came out cool enough to see the vapor to humidify the house. These houses were always warm and cozy in the dread of winter. Never appreciated till now how all this was accomplished.

Wild Bill

District heating

Dan,
My wife and I adopted our son from Russia, we were in Moscow and Krasnoyarsk (due North of Mongolia -40 when we got off "De plane".

In Moscow, I believe they had central H20 heating, 20 or so kilometers outside of the city I saw a huge power plant (no camera handy as our driver sped us by).

In Krasnoyarsk, we had our hotel windows open at night despite the aforementioned temperature. The only "control" for the room temperature was a diverting ball valve on the panel radiator in our "updated" room. I could make a living installing thermostatic radiator valves there!!! We had a wonderful experience, the country was beautiful and the people SO very friendly.

Clif Heeney_2

Info about Moscow

My wife Tuuli, called her favorite aunt Evi in Moscow today. Evi or her husband Sergei believes that almost all if not all of the district heating in Moscow is with water. They have heard of a few older buildings, and some of the new ones being heated with steam, but they don't think that is being done with a district heating system. More than likely it that the individual building has it's own steam boiler dedicated for the use of that building. They weren't able to verify that though!

We asked them if they knew of anyone who works in that utility and unfortunately they don't. They are going to ask around though, to try and find someone who either works in one of the district heating plants and who has a friend who does. I'll let you know what they find out -- if anything.

They also believe that most, if not all, district heating in Russia would be with water, NOT steam. They have traveled somewhat and they have only seen hot water being utilized in district heating set-ups.

I was born and raised in Vernal, Utah. I have lived in Estonia for about 6 years and have been married to my wife who is an Estonian for 5 1/2 years. We have two children, our daughter Nancy who turned 2 years old today and David who is 8 months old.

DanHolohan

Thanks so much for the info.

Fascinating stuff. People are people, eh?

DanHolohan

Thanks, Clif

Your insights, and connnections, are really helping me understand.

How's life in Estonia? Love to hear the story of how you came to be there. Thanks.

Christian Egli

Steamy hot water - does that answe the question?

I remembered that in 2003 there was a large disctrict heating outage in Russia, I searched and I found something about district heating in Moscow. They have a plan for year round hot water thanks to new pipes.

Read on.

Thanks


Aug. 7, 2003: #7279 • #7280 • JRL Home
#21 - JRL 7280
Moscow Times
August 7, 2003
A Plan for Year-Round Hot Water
By Valeria Korchagina
Staff Writer

It's summer, and your hot water is turned off again.

But the shutoff that often bewilders foreigners unfamiliar with the peculiarities of Moscow life might not always be an annual tradition: Engineers say a solution is in sight.

However, it might take 200 years before your neighborhood has hot water all year round.

Moscow Heating Network, the subsidiary of Mosenergo in charge of the main pipes that ship steamy-hot water from electric power plants to neighborhood heat-exchange points, sees the city's savior in a new pipe that is resistant to rust -- the main culprit that forces it to turn off hot water for repairs every summer.

The pipes are protected by a special water- and heat-proof coating that is several centimeters thick and filled with rust-fighting polyurethane foam, said Viktor Tarasov, deputy chief engineer at Moscow Heating Network, or Teploseti. The pipes also are equipped with detectors that alert engineers about the need for small repairs before any major damage occurs.

All this means that the new pipes can remain in service for 25 to 30 years without any major repairs, thus allowing hot water to be kept on all the time, Tarasov said.

Just about every neighborhood takes its turn without hot water for three weeks every summer as engineers repair a vast and aging pipeline system that stretches for thousands of kilometers under -- and sometimes over -- the ground.

"The problem is that Moscow's heating and hot-water supply systems have a level of technology dating back to somewhere in the 1930s," Tarasov said in a recent interview.

In most cases, city dwellers get their heating and hot water through a complicated system in which extra-hot water -- heated up to 130 degrees Celsius in the peak of the winter -- is pumped through the main pipes to the neighborhood heat-exchange points. There, through special heat-exchange equipment, household water is warmed up -- but not mixed with -- the water from the power plants and the cooled-off steam is returned to the plants. Some of the longest main pipes stretch 20 kilometers from the power plants to the neighborhood heat-exchange points, or nearly halfway across the city, Tarasov said.

This relatively unique heating and hot-water system was adopted primarily due to the city's vast size and the area's cold climate, Tarasov said. "And since electricity is produced anyway, the hot steam is effectively a byproduct that is a free source of heat," he said. "It would have been silly to waste it."

While recycling steam from power plants sounds like a good, environmentally friendly idea, the downside is that the monstrous web of rusting pipes requires near-continuous maintenance.

Unless, of course, the pipes happen to be of the new coated variety. A few Moscow residents with these pipes already have hot water all year around, but they mostly in the outskirts of the city in newly built housing, Tarasov said.

The rest of the city probably will have to wait years, he said.

The big hitch to laying the new pipes across the capital is a typical one: money. According to Tarasov, replacing the pipes in the city's central district alone would cost about 14 billion rubles ($460 million), roughly the size of Teploseti's maintenance budget for 15 years.

In addition, the scale of the problem is huge. Teploseti controls some 2,400 kilometers of the city's mainstream pipes, which make up 70 percent of the total main-pipe network. Last year, only 10 kilometers of new pipe were laid, bringing the length of pipe replaced over the past decade to just 60 kilometers.

Factor into that all the smaller pipes connecting apartment buildings with the neighborhood heat-exchange points -- which also would have to be replaced for year-around hot water -- and the picture begins to look rather grim.

Tarasov, however, was optimistic. Mosenergo recently built a plant that can produce up to 150 kilometers of the new coated pipes per year. This, he said, should significantly speed up the replacement of pipes.

"But major repairs also would mean that the cost of heating and hot water would have to go up significantly, and the question remains: Do people want to pay more and always have hot water or leave things as they are now and opt for the lower prices," Tarasov said.




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Aug. 7, 2003: #7279 • #7280 • JRL Home

Eric Peterson_3

District Heating in Finland

Central heating is a feature of some housing developments in Finland. A friend of mine bought a new house in the Helsinki area and the whole development is heated by a central system which provides hot water. I remember walking to his house from the bus stop and seeing where they were laying the heating distribution pipes deep in the ground for a different set of houses.
The control mechanism was TRVs but I don't know how they charged for usage. I do know that these types of houses are very well made, insulated, and comfortable all through the winter. Actually winters near Helsinki are not that much colder than Chicago.
One other thing, my friend views American housing developments (especially apartment complexes with hot air heating) as somewhat barbaric in that it seems wasteful to have everyone have to have a separate heating appliance in their unit. Wasteful and noisy (hot air that is).

--Eric Peterson

Glen

Vancouver B.C.

Has a very large steam system that is piped via underground passages and tunnels to many commercial buildings. it's been years since i wandered through some of them. The boiler is on the east side of downtown and probably services a 10 square block area. In other areas of the province a central steam system was common too. Braylorne, B.C. an old gold mining town - now a ghost town - was a great example. 10 and 12 inch mains with risers to each building. Buildings for the most part are gone but the risers are still there. I am sure other remote areas were heated the same way - company town, company store, company heat. One stop shopping.

Clif Heeney_2

No Pics!

Leo, Dan and all Wallies,

Sorry, but I don't have any photos of any of the district heating plants here in Tallinn! Maybe you would like to travel here and while visiting the best preserved medieval city in northern Europe, we could go visit one of the plants. What say you?

If you are interested in seeing some of what the original part of Tallinn looks like, what we call Old Town, go to http://www.tallinn.info/html/

clammy

nurnberg

While in germany years ago i had checked out one of the engery conservatory they had layouts of high pressure high temp water systems using heat exchangers to absorb heat from steam condensate under high pressure and temp and pump it through the city to plat exchangers and modulating valves with out door resets feeding the correct amount of heat needed into the plate from the system side a main pump two stage with a pdv and a watt meter welded onto main system feed every rad in the building has one of these watt reader weld onto them and of course a trv also but once a year they come and read every one in the building and the main one on the pump outlet after the by pass they also have one on the plate exchanger main inlet with all this they figure the over all engery use and who used to much and they get billed .These watts counters are every where in germany or at least in all of the apartment buildings ,after going to germany in 96 my whole view of taking pride in your work really took a grasp amazing stuff if the fuel and the taxes created on them are raised enough things start to change huh? peace clammy

John Mills_3

here's some statistics

http://www.energy.rochester.edu/dh/largest.htm

The 2 biggest district heat systems are in Russia. Surprising to see little old Indy was 2nd biggest in the US.

DanHolohan

Great stuff, lads.

And much appreciated!

Matt Undy

Suherheated Water?

So If i've read this right, most of the hot water systems are using water under pressure heated to above its boiling point at atmospheric? This will hold a whole lot more energy per volume than steam but it will also result in varying degrees of explosion at a leak, correct? Live steam, especially high pressure, is dangerous enough but the water seems very dangerous. I'm imagining somethng like liquid refrigerant/cooling spray/"air" duster evaporating only the thole thing is scalding hot.

BTW, superheat isn't the right term, its actually slightly subcooled, it is just pressureized.

Matt

Weezbo

i am thinking 40 psi ish

Matt Undy

I am thinking I don't want to be around when a few GPM or more of water are flashing into a few thousand GPM of steam from a leak :-)

It is intersting though. Thanks for asking Dan. Iwonder if those statistics about Detroit are current. I know that Detroit Edison was cutting off some neighborhoods a couple years ago. I grew up in metro Detroit and went to Wayne State in Detroit where their buildings were on district steam from Detroit Edison. I now work for the University of Michigan and I know that we have a district steam system fed from the University's power plant but I don't know the specifics of the system. I do know that i've looked in the wondows of the power plant and seen some valves that should only be in a museum...

Matt

Clif Heeney_2

District Heating In Finland

Just got off the telephone with our Finnish friends who live in Vantaa, a suburb of Helsinki. Their apartment building is heated by district heating, as most are in Helsinki. They are not charged by how much hot heating water that they use, but rather a flat rate based upon the square meters of their flat. It is built into their monthly maintenance fee. Each apartment or flat is owned by an individual and they all pay a monthly maintenance fee, I think similiar to what a condo owner would pay in the USA. No steam is used in their systems.

Mike T., Swampeast MO

Here's some stuff culled from the Web

Currently, there are in Russia a lot of DH systems with various degrees of centralization. Some DH systems provide 100 percent of a city’s heat, others are smaller, and there are a few decentralized systems in cities (these are with the capacity below 20 Gcal/hour). However, DH systems provide almost 80 percent of the heat in Russia.

The main energy sources are co-generation power plants (CHPs) and industrial and municipal boiler-houses. District heating networks usually include central distribution stations.

Currently, there are 257,000 km of heat pipes with the diameters between 50 and 1,400 mm (average diameter is 300 mm). Of these 25,000 km are heat mains and 232,000 km of distribution pipes. (It should be noted that in Russia there is double piping -- for supply and return water, -- so all these figures should be doubled).

Basically, heat pipes are located underground in concrete tunnels (conduits) and insulated mainly with mineral wool. Only 10 percent of all pipes are placed underground and insulated with foamed concrete clued to the pipes with bitumen. Given the above technologies, pipes' lifetime is only 10-15 years which is 1.5-2 times less than abroad. Only the "rich" cities can afford pipes preinsulated by polyurethane foam. For example, in Moscow 5 percent of the pipelines in Moscow are this type.

---------------------------

Tens of thousands of Russian apartments have been mass produced since World War II using a few standard designs. The Zhukovskij blower door testing involved standard 14 story, 9 story and 5 story designs. In these designs a typical one- bedroom apartment contains a kitchen a bathroom and one sleeping/living room totalling about 33.5-m2 (370-sf). A typical 54-m2 (580-sf) two-bedroom apartment has an additional sleeping/living room and a typical 73-m2 (790-sf) three-bedroom apartment has two additional sleeping/living rooms. Most of the common areas such as the lobby, stairwells, halls and elevators are poorly maintained and barely lit, but the apartments were comfortably furnished.

The buildings tested in Zhukovskij were all constructed of precast concrete panels. In this type of building there are many joints that must be sealed after the panels are lifted into place. There are no insulation cavities in the side walls of the Zhukovskij buildings so that the total wall insulation value is provided by the 14-inch thick exterior concrete panels. Our heat flux measurements from Zhukovskij showed that the effective R value was about R-3, as expected for 100- lbm/ft3 concrete. All windows are wooden casement, double-pane, with no effective weatherstripping; windows cover over 16% of the total wall area and represent about 10% of the apartment floor area. Apartments in regions further north than Moscow were reported to have triple-pane windows. Most of the residents used foam rubber, newspaper, or tape to seal up their windows as much as possible around October 15 each year and unsealed them around April 15. This helped make up for the lack of effective permanent weatherstripping on the windows.

Heating is delivered by a radiator located below each window. The radiators receive hot water via an extensive distribution system from a central district heating plant. Apartments generally do not have individual controls or metering and furthermore, individual controls and meters cannot be easily retrofit in many buildings because radiators are typically plumbed vertically in series. Heat delivery is controlled by varying the hot water supply temperature with daily temperature at the central plant.

---------------------------------

Municipally-owned utilities are the other major market for energy-efficiency equipment. Centralized district heating systems supply 70 percent of Russian households with heat and hot water, and more than 1,000 large systems (serving at least 10,000 users) consume 450-500 million gigajoules of heat annually (approximately six barrels of oil produce one gigajoule of heat). Cities also subsidize heat and hot water services with heat subsidies now dominating many municipal budgets. Some Russian cities spend a third of their budget subsidizing citizens' heat and hot water.

The financial burdens imposed by these obligations have led cities to seek ways to reduce their energy consumption. In Chelyabinsk, which spends more on heat than on health care, municipal officials earmarked $750,000 this year for energy-efficiency improvements to their district heating system. The money saved from the efficiency program will be re-invested in further improvements to the system.

District Heating in St. Petersburg

District Heating in Kazakhstan (Pretty good description of the system starting on p. 12)

---------------------------------------

The district systems for residential use seem to be giant two-pipe hot water systems with reset based on the weather. Many? most? people live in large apartment buildings. VERY little in the way of individual temperature control as radiators are typically piped in one-pipe vertical loops underneath windows. Can't find any mention of the temperature of the water so don't know if its highly pressurized water above the boiling point or not.

Christian Egli

A round of hot water

It is saddening to read that there isn't much of steam heating used in Europe instead of the overheated water, which means, the place is a paradise for heat exchanger and pumping station manufacturers.

With no such thing as piping the steam heat straight from the boiler plant to the radiators in each dwelling, it is no surprise to me that these hot water systems have maintenance and control issues and that they go cold from time to time.

From the beginning, I think the US had it right with steam and still has it right after more than 100 years. Steam is a thing of marvel in small systems and even more so in large buildings, it must follow that it should be the method of choice in district heating... but we hold these truths to be self evident...

Talking about heat with people in western Europe and asking questions about how they - do it - over there, I have found that there is a total lack of understanding about steam. Most often, after I proudly say I've got steam heat, they tell me, oh, us, well, we just burn oil in our boiler!?

This makes sense to them because it seems they refer to the big heat exchanger in the basement that transfers the heat from the district loop to the house loop as their hot water boiler. It could burn steam, oil or natural gas, it would make no difference.

Dan, I think Europeans are waiting for your books to be translated. Thanks for asking the good questions.

Matt Undy

oops

Oops, I think I had briefly forgot high school physics yesterday. All the water leaking would not flash to steam, just enough water would flash to steam to remove enough heat to cool the water below the atmospheric boiling point.

I think I am wrong about the very hot water under pressure carrying more heat than steam but the more I think about it the more I'm not sure. There is a lot more mass of water than steam but the steam has a lot more heat to give up by losing its heat of vaporization in condensing than water does in just cooling. I think it depends on:

1. What tempurature the water or steam/condensate is ultimately cooled to
2. What pressure the steam is at and therefore its density and the amount of steam delivered through a given pipe size
3. The tempurature and pressure of the comparable hot water
4. The superheat of the steam.

Maybe somone else wants to figure this out but the concept seems much more interesting to me than the actual math. The ratio of the actual steam pressure to atmospheric would be used to correct the specific heat of steam at atmospheric. This would also be used to correct the volume of steam in figuring the latent heat of vaporization, then it would just be straight specific heat of water from the condensing tempurature to the final tempurature.

The pressurized water would just be straight latent heat calculation from intital tempurature to final tempurature.

Matt

Mike T., Swampeast MO

Will try, but it will take some math...

Here's an interesting thing to start with:

"At a pressure of 220 bar [3,191 psi], the volume of steam becomes similar to that of water (2.74 and 3.57) and the boiling temperature becomes so high (373.8°C) [704.8°F] that very little latent heat is needed to convert the water into steam. At 221 bar the two volumes are the same (3.16) and no latent heat is needed. At this and higher pressures, a clear distinction between a liquid and a gas is not possible. At a low temperature it will look like a liquid and at a high temperature it will look like a gas and in between a bit like both."

The point being that steam at low pressure takes up a lot of space, but at extremely high pressure it takes up the same space as water at the same temperature.

Say we have one pound of saturated steam at 75# of pressure.

That one pound takes up 5.82 cubic feet. There are about 904.5 BTUs of heat in the vapor and about 277.43 BTUs in the water were it cooled to 32°. Let's say we use all of the heat in the vapor and the heat of the water down to 140°. That's about 904.5 + (212-140) = 976.5 BTUs we got out of the one pound of steam.

But, that pound takes up 5.82 cubic feet. So, to find the amount of heat available in one cubic foot we have to divide by 5.82. 976.5 / 5.82 = 167.78 BTUs available in one cubic foot.

Now, let's put a pound of water under that same 75 pounds of pressure and heat as hot as possible without producing steam. That pound of water will be about 308°. If we return at the same temperature (140°) we get about 308-140 = 168 BTUs available per pound. To compare, we now have to find out how many pounds of 308° water are contained in a cubic foot. It should weigh about 56.7 pounds per cubic foot so we have 168 * 56.7 = 9,525.6 BTUs

So, using similar conditions and usage, we have 9,525.6 BTUs available in a cubic foot of hottest possible water at 75 pounds of pressure compared to 167.78 BTUs available in one cubic foot of saturated steam at 75 pounds of pressure.

So, as you suspected there is MUCH, MUCH, MUCH more usable energy for a given volume of "superheated" water compared to saturated steam.

Actually producing and working with water under those conditions is (I believe) rather difficult and exceedingly dangerous. Of course steam at 75 psi isn't exactly benign either...

Finally though let's see just how much heat we can transfer through a pipe of given size with water and steam under similar pressure conditions.

Using "generally regarded as safe design velocities" we can move about 750 pounds of 75 psi steam through a 10" pipe in one minute. For that 976.6 "used" BTUs in a pound of steam, this becomes 750 * 976.6 = 732,450 BTUs per minute or 732,450 * 60 = 43,947,000 BTUs per hour.

In a 10" pipe we can generally move water at about 6.5 feet per second without problem. 10" schedule 40 pipe is nominally 10.02" inside diameter so 1 inch of such pipe holds 3.14 * (5.01 ^ 2) = 78.85 cubic inches. 6.5 feet of the pipe hold about 78.85 * ((6 * 12) + 6) = 6,150.3 cubic inches. 6,1550.3 cubic inches = 3.56 cubic feet. So, we can move 3.56 cubic feet per second. Each cubic foot of water was giving us 9,525.6 BTUs so we get 3.56 * 9,525.6 = 33,911 BTUs per second. 33,911 * 60 = 2,034,660 BTUs per minute. 234,660 * 60 = 122,079,600 BTUs per hour.

So....by doing my best to compare "apples with oranges" we can reasonably expect to get MUCH more heat with water than with steam. With everything under conditions as similar as I can produce, we would be using 43 million BTUs per hour with steam, compared to 122 million BTUs per hour with water. Water is about 2.84 times greater in this situation. Don't forget the importance of that first quote! As the pressure is lowered, the disparity will increase!

I could not find actual temperatures typical in Russian district heating systems posted on the web. But everything does seem to concur that they are water systems with reset. Given the scope, sizing and materials of the systems, my guess would be that in brutally cold weather the supply water is significantly hotter than 212°F--but probably still significantly less than this example with water at 308°.

Mike T., Swampeast MO

For those of you, like me, who have a hard time understanding

the differences between steam, vapor, saturated steam, saturated vapor, etc., etc., etc., that quote at the beginning of my previous message FINALLY made the light bulb glow in my head!!!

Latent heat isn't the energy required to drive water molecules apart, it's the energy required to keep water molecules from clustering together! I know that sounds similar, but now I "see" how water exists in the air at "earthly" temperatures! It finally makes sense how you can put more heat into steam than required for it to be steam under a certain pressure in the first place!

Mike T., Swampeast MO

Now My Question

IF they are using really hot, pressurized water for supply, extract a lot of heat and keep the system completely closed, does this mean that they can circulate the water long distances and to the top of quite high buildings without pumps? As the water cools, pressure will drop. High pressure goes to low. 75# supply pressure with WAY less at return--sounds like their district systems [could] be like giant, old, Honeywell "heat generator" systems....

Glen

but ---

what about inherent restrictions built into the piping systems. Wouldn't a circulator be required to overcome these friction losses? Or is the compensation then by oversizing piping? UUUMMM?

Mike T., Swampeast MO

Second Light Bulb

Thank you Matt Undy for making me "waste" about 90 minutes this morning...

Steam, vapor, humidity, etc. FINALLY makes sense!

It was the idea of "steam heat" that kept messing me up! Steam has kinetic energy that can must be CONVERTED to get latent energy in the form of heat!!!! Duh! I'd read it, I supposedly "knew" it, but now I finally understand it...

Frankly, steam seems MUCH better a way to get motive power than heat--particularly when you "superheat" the steam. That superheat gets converted VERY efficiently into kinetic energy as the steam attempts to cool.

To Dan: I now really understand what you were telling me about the Coors plant when we first met at Wetstock!

Mike T., Swampeast MO

That's another set of calculations...

It just seemed that it might be possible.

But it seemed to work well enough to make Honeywell Honeywell...