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As an American it completely breaks my expectations that district heating not only works can be more efficient that decentralized heating. The amount of heat lo
by pavon 4y ago
As an American it completely breaks my expectations that district heating not only works can be more efficient that decentralized heating. The amount of heat lost just moving water from the water heater on one side of the house to the shower on the other is ridiculously high in houses here. The idea that you can insulate well enough to efficiently move heat across a city is amazing to me.
- deleted 4y ago[deleted]
- Swizec 4y agoMy hometown has a power plant in city center. During winter it uses the entire downtown area as a heat sink. It's great. Power plant gets cooling for its hot water, city residents get cheap heating for their homes. Best part is you don't even care about heat loss because you're trying to get rid of all that heat anyway. This scheme has been inplace since the 60's. https://en.wikipedia.org/wiki/Ljubljana_Power_Station https://en.wikipedia.org/wiki/Ljubljana_Power_Station District Heating is quite popular in much of the world. USA built the first such system back in 1853. https://en.wikipedia.org/wiki/District_heating https://en.wikipedia.org/wiki/District_heating
- teruakohatu 4y agoGiven how much health problems are caused by coal power plants, not sure it is that great to live near one. But if you have to have coal, it makes good sense to harvest the energy rather than wastefully pumping the steam into cooling towers.
- Swizec 4y agoI mean it’s already there and has been for 60 years. I’m sure its polution pales in comparison to the 200,000+ cars driving in the area daily. Back when the coal power plant was built it was pretty normal to live near coal burning things.
- stephen_g 4y agoUnless it has a lot of flue scrubbing, it's likely to be far, far worse than 200,000 reasonably modern cars in terms of things like fine particulate matter emissions, NOx and SOx emissions, etc. which are the real bad ones for health issues.
- gamegoblin 4y agoMany American universities use district heating for the whole campus. Also, as made famous by the many steam vents in NYC movie shots: https://en.wikipedia.org/wiki/New_York_City_steam_system https://en.wikipedia.org/wiki/New_York_City_steam_system. More info: https://en.wikipedia.org/wiki/District_heating#United_States https://en.wikipedia.org/wiki/District_heating#United_States
- dwighttk 4y agoAs the first dorm on the loop my freshman year, I’d get back from crew practice, go into the bathroom, turn on all three showers, and flush the three toilets about three times each to flush all of the hot water out of the cold water line so that I wouldn’t burn myself when taking a shower. I never heard if anyone got hurt when I took a day off and slept in.
- jefftk 4y agoWhy was the cold water line hot?
- dwighttk 4y agoIt was next to the hot water line and not insulated (enough) and it had pretty much just been sitting there all night.
- pastage 4y agoLucky you didn't get legionella. That is not up to spec, cold water lines should always be below 25°c. I have never seen such an installation, even in development countries it was done correctly.
- ClumsyPilot 4y agosame, been in two developing countries with similar heating system, never seen such a problem. sounds disturbing
- konschubert 4y agoAs a German living in a city with mandatory district heating... the end result is to be that people seem pay more for heating than they would with a decentralised system. I think that's mostly due to the high upkeep costs of the system, though, the transmission loss is quite manageable, I think. Of course there are arguments to be made that when accounting for the cost of installing a heating system, and the space it takes, the premium paid for district heating is not that high. But still... if district heating is so smart, why ain't it cheaper? What's nice about it, and maybe hard to quantify, is how this limits air pollution in the city. However, people are still allowed wood burning ovens... which they are now all turning to since the district heat is getting really, really expensive..
- teruakohatu 4y ago> What's nice about it, and maybe hard to quantify, is how this limits air pollution in the city. It should be simple to quantify. If gas is used for heating I can't think there would be any improvement. Local heating with a heatpump would be an improvement if the power supply mix is greener than gas only, maybe worse if the power is all coal.
- Symbiote 4y agoI find district heating in Copenhagen to be good value, and it seems to be a good deal greeted. https://celsiuscity.eu/district-heating-prices-highly-competitive-in-denmark/ https://celsiuscity.eu/district-heating-prices-highly-compet...
- japanuspus 4y agoOne reason Denmark has very affordable district heating is that it is based on "waste heat" from power plants, and "waste heat" is exempt of energy taxes (because those are paid on the primary energy sale, i.e. the electricity). This comes with some perverse incentives in an age of renewables: 1. If the power plants use surplus electricity to provide district heating it is no longer a "waste product" and consequently taxed. Since the power plant cannot run without generating electricity, this leads to periods of negative power prices. 2. Cooling water from e.g. data centers is too cold for district heating, but it would be energy efficient to use heat pumps to extract that energy. This is not done, because the product would be subject to full energy taxes as it is not a waste product.
- vkou 4y ago> The idea that you can insulate well enough to efficiently move heat across a city is amazing to me. It only works well when heating is 'free' - such as when you're using waste heat from a nuclear power plant, or from overproducing solar/wind plants.
- pretdl 4y ago
- dubswithus 4y agoI have a hot water recirculator installed and love it. It's even faster than on demand. Faster hot water incentivizes hand washing. Just think about how many more people would wash their hands at the airport if they didn't have to wait 2 minutes (or forever) to get hot water.
- ortusdux 4y agoI'm looking at going this route before I finish the basement. The master shower is the furthest point from the heater, and it takes a solid 2-3 gallons to get hot water in the morning. The math didn't make sense until I put in a heat-pump water heater. Now I average $170/year to heat my water, and the recirc should only add ~$30/year. My pipes are well insulated, but I'm in a colder climate so loosing heat into the walls just lowers my heating bill.
- bluSCALE4 4y agoI installed a recirculating pump and had it on the timer. But then for some reason, I switched it to always on and it's so much nicer. Hot water is always hot.
- dubswithus 4y agoI’ve been tempted to do that. Sometimes I wake up at odd hours when it’s not running.
- Nick87633 4y agoI wash my hands with the cool water that initially comes out?
- dubswithus 4y agoCool water? What about freezing water in the winter?
- 4y ago
- zdragnar 4y agoAmerican here. Most household water pipes really aren't insulated, or aren't insulated well enough. Plus, moving water under the frostline means that the ground it's moving through might be upwards of 55 degrees F. My house came with an outdoor wood boiler (it's more a rural cabin than a house, really). It moves 180*F water from the boiler 50 feet underground into the house, where it runs through an air exchanger in the central air system and pipes it back out to be reheated. Newer models of these things can get upwards of 98-99% burn efficiency, and ~85% heat transfer efficiency- as good as or better than you can get with standard efficiency furnaces.
- samatman 4y agoVolume to surface area: for every doubling of diameter you have 1/16th the losses, before factoring in insulation. 1/16th probably sounds high, but the extra halving is because flow rate increases as radius^4, not cubed as one might guess.
- ethagknight 4y agoFor USA, district heating made sense in the coal power era. Today, why burn natural gas at a central plant and then have to manage a complex steam distribution network with associated losses when you can simply distribute natural gas instead and get 98% AFUE at the point of use? Even better is a heat pump with gas backup at point of use. Triumph of technology. Also, You dont really insulate the steam distribution pipes, you just count the loss bug as a feature “heated roads and sidewalks to melt snow!” Lastly, district heat doest work in American low density
- FooBarWidget 4y agoHere in Netherlands, districted heating is considered green because the centralized heat is not generated using coal or gas. Instead the heat comes from burning trash or other industrial waste heat.
- zajio1am 4y agoDistrict heating can use cogeneration in nearby power plant, so it essentially reuses waste heat from electricity production. There are even district heatings that use heat from nearby nuclear power plant. Also note that modern systems does not use steam distribution, but high-pressure hot water distribution.
- osigurdson 4y agoGeothermal makes so much sense conceptually. It seems ridiculous to run natural gas pipelines everywhere when there is a limitless supply of heat under every house provided one drills down far enough. Hopefully the process can be simplified and costs can be reduced significantly.
- adrianN 4y agoIf you burn the gas in a power plant you turn something like 40% into electricity. You can deliver something like half of the remaining Joules as heat to homes, raising the overall efficiency to 60% or so. You can then use the 40% you have as electricity to run heat pumps, which put out something like 2-5 Joules of heat per Joule of electricity. In total this gives you a lot more Joules of heat per unit of gas than just burning the gas in the homes directly.
- TheSpiceIsLife 4y agoAustralian here. The idea that anything can be insulated at all is fucking novel. New construction has minimum standards these days, but that does nothing for the majority of older house which have single glazed window, iron roofs, and no insulation whatsoever and, if you're renting, lucky to have a heat pump. And yeah, no insulation on the hot water piping means massive loses from water heater to tap.
- _carbyau_ 4y agoYup, we got a ways to go. Insulation is simple and cheap. All construction should friggin' max it out. Double glazing is now not heinously expensive anymore. But still seems to have the Australia Tax.
- halper 4y agoAs a Swede, I've never been as cold as in Australia in winter! My Australian friends can't believe -20 degrees is survivable, but the thing is that our houses have a different temperature on the inside ;) In Hobart I once lived in a place that had radiators. I made the mistake of keeping the place comfortable and it cost me $700 of cheap hydro power in a fortnight.
- conk 4y agoEven just adding a little inuslation to a pipe will drop the heat loss down to a few watts/ft when dealing with a pretty large delta T. If you’re using 20k+ watts to heat a home the losses on the pipe are minimal. And I’m guessing these homes are all pretty close together. Not a mile apart.
- epistasis 4y agoThis is actually a really good business for natural gas utilities to switch to if they want to survive in the future. They have tons of experience with pipes, they can swap gas furnaces for heat pumps and exchangers. And it turns out that the areas that district heating works well with are really comparable to where it makes sense to pump natural gas. Yoi don't necessarily need heated pipes, just using the ambient temp in the ground is usually good, with very small bits of storage/heating.
- schmichael 4y agoKlamath Falls, OR uses geothermal heat for municipal hot water including warmed sidewalks! https://www.klamathfalls.city/232/Geothermal https://www.klamathfalls.city/232/Geothermal
- bjelkeman-again 4y agoIt is cost effective, efficient and saves on emissions. Nowadays, all major cities and towns in Sweden have district heating systems. Stockholm also has a distric cooling system, although not as developed. More info “District heating and cooling in Sweden” https://www.sciencedirect.com/science/article/pii/S0360544217304140 https://www.sciencedirect.com/science/article/pii/S036054421...
- kitd 4y agoI once visited a geothermal plant about 20km outside Reykjavik that supplies hot water for heating the city. Even in the depths of Icelandic winter, the temperature only drops 1 deg C between the plant and the city. A lot of Rockwool around the pipe IIRC.
- deleted 4y ago[deleted]
- bbarn 4y agoI live on a small island in Iceland, too far across the sea to pipe Geothermal water to, so the town heats water electrically and pipes it to homes instead. It's not very efficient, and it is rather expensive. It's kind of interesting because there just aren't hot water heaters for sale here, and Icelandic homes are built with that assumption. I'm on the far side of the island from the plant, and in winter you can absolutely tell the difference in water temperature. In summer months there's an anti-scald unit in every home that's necessary to prevent it being too hot, but in winter sometimes you end up with rather lackluster showers.
- lazide 4y agoIs that because of heat losses getting to you, or because enough heat is being used to heat the houses that the overall temp is lower?
- bbarn 4y agoI would have to imagine heat loss in transit, as it's not a problem anywhere else other than the far side. The plant itself has a lot of waste heat and not boiling too much water is a concern.
- fulafel 4y agoTraditionally when using combustion plants the great advantage in nordic countries comes from CHP (combined heat and power), you can extract much more energy from the fuel this way vs having separate electricity and heat plants. But yep great insulation in the network is a requirement.
- 2Gkashmiri 4y agoi have been thinking about getting a solar water heater>heat pump>radiator to warm up my home but the costs just dont make sense because of the heat pump. i am told the life expectancy of a good heatpump is like 10 years, that amount divided by only 10 winters it is expected to see is more than what we currently pay for electricity in winters, accepting that we don't currently have whole house heating, (we rely on personal hot water bottles/electric blankets in bed)
- killerpopiller 4y agothat can't be true. In Germany it is quite a trend now, but they are installed for many years. What I can read in the boards is not that discouraging. Where does this 10 year number come from?
- 2Gkashmiri 4y agohttps://www.racold.com/heat-pump-water-heaters https://www.racold.com/heat-pump-water-heaters >Our heat pump water heater comes with a 2- years warranty and a dependable service for the inner tank. this is like the premium heat pump contract manufacturer. good brand with a good reputation. roughly 10 years is what the installer told me. refrigerators in india come with a 5+10 year warranty usually so this 2 year warranty is indicative.
- Gasp0de 4y agoThe internet tells me that split-ac systems (basically small heat pumps) have a life expectancy of 10-20 years. That's not too bad, for example an oil-based heating system (as we have in our german basement) also only has a life expectancy of 20 years and has way less moving parts.
- dan-robertson 4y agoWell there is district steam in New York. Another thing may be density: you will lose less heat due to distance travelled for central parts of New York than for a less dense(?) European city which is itself much much denser than a typical American suburb-city
- einpoklum 4y agoI wonder how far out one can scale a cooling, rather than heating, system. Probably not worth it making it city-wide, but then - who knows? If it works for heating...
- fulafel 4y agoThere are district cooling systems as well, there don't seem to be any scale problems in the engineering. It's more attractive if you have a body of cool water nearby for the heat pumps. But the users need to have different heat exchangers than just radiators, if you just put cold water into radiators they'll start sweating precipitation and you'll get mold etc damage.
- oblio 4y agoWell, if you want to hear from the darkside... Romania. Badly maintained infrastructure (as an American you're probably familiar with the idea). Keeps breaking down. Not enough money invested to bring it to modern standards. Pipes are not well insulated, they break down constantly, huge leakages and losses. Cost of heating is so high that about 20% or more of the entire Bucharest city budget (I've just checked, budget: ~$1.8 billion, subsidies: ~$450 million; Bucharest has about 2.2 million people) is spent on subsidizing heat for poor families. Heating/hot water sometimes go down for hours or even days in random districts. In many districts district heating is mandatory because everyone who can pull out does so and that makes the system even more inefficient, which would cause the collapse of the entire system, hurting poor families even more.
- deleted 4y ago[deleted]
- lazide 4y agoHow can anyone function if their heat is down for days? Bucharest isn’t in a tropical climate!
- oblio 4y agoThey do try to fix it and in the vast majority of cases it's a bunch of hours. If it's longer than that, people have electric heaters, some use their gas stoves... you can kind of handle that for a short while. And it's usually quite localized, some blocks don't have it, obviously if it affects large chunks of the population priority goes up.