271–280 of 307 posts
Curious, can this be used in reverse, to keep sand cool and use it to cool down houses? Would bring down a lot of AC usage in tropical countries.
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Water heater failure is also easy to avoid by annual or seasonal flushing of any accumulated sediment and checking the anode. As long as the anode is replaced, the water heater should be fine. I would expect a large condo association's maintenance staff to be able to handle this sort of thing very easily.
The ceramic lining of a water heater cracks due to thermal stress over time. Pure stainless steel water tanks don't have this flaw, but they aren't they common.
Depends a lot on how corrosive/nasty the water is in an area though. Some are just nuts.
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> As 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. So, in America, it is very common for hot water tanks to suddenly fail, leaking water everywhere and causing massive amounts of property damage and even creating health hazards through mold. In a not-insane world, all hot water tanks would come wi…
> in America, it is very common for hot water tanks to suddenly fail, leaking water everywhere and causing massive amounts of property damage and even creating health hazards through mold. I've had them fail and leak many times. But I had the water heater put in the basement next to a floor drain, and the floor slopes slightly towards the drain. No damage whatsoever from leaks, and it wasn't an emergency to get it fi…
A good idea, but not sure it it’s code, is to do the same with the clothes washer.
Flood sensors (there are ones with auto water shutoffs too) for the clothes and dish washers are a good idea too.
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There’s a cheap ($20?) add on for our water heater that adds a conductivity sensor in the drip pan, and a shutoff valve on the inlet. There’s a slightly more expensive variant from another company that supposedly looks at flow for the whole house, and cuts water off due to slow leaks or burst pipes. I’m shocked that the water heater cutoff valve isn’t required by code. In contrast, plumbed drain lines for water tank…
> There’s a cheap ($20?) add on for our water heater that adds a conductivity sensor in the drip pan, and a shutoff valve on the inlet. Oh I know, they are awesome. They should come standard, and more people should know about them. It is one of those things I try to bring up in conversations at random, because holy crap the # of people I know who have had water damage from their water heating dramatically failing is…
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Tanks don't fail unless the anode gets depleted. You seriously need to tell your condo association to get their maintenance people to flush the water heaters regularly (seasonally or annually) and check/change the anodes. If they're gas-fired heaters, the burner and air intakes should be getting cleaned. If this isn't being done, it's probably because your maintenance is being done by plumbers, who have convinced eve…
How does an anode help against a thermal expansion crack in the wall?
2) anodes stop heavy corrosion in the system by sacrificing themselves.
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.
Well, 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, budge…
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For 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 pip…
If 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 j…
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I 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.
I 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 ab…
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.
I 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...
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.
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Heat keeps leaking out. The amount of stored heat is proportional to the cube of the linear size, the leak rate is proportional to the surface area (square of the linear size). Hence, the bigger the storage, the higher the efficiency. Same why a flea can jump >10x its height, and a human cannot (square growth of strength, cubic growth of weight).
Thanks for the answer. I suppose the answer is a decent insulation on the box. It only has to last for a few hours. Of course, some engineering would have to go into optimizing the size of the rocks and the surface area / mass for the expected use.
Basically, if you only have a small amount of sand, it’s harder to keep it warm for longer (more surface area for the mass, so more insulation required), and harder to deal with effectively (fan needs to blow much harder when it’s only warm, much less when it’s hot), etc.