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Hot water storage is very cheap. Water has tremendous heat capacity. So that's a great example about what can be scheduled in a flexible way. If something is

Hot water storage is very cheap. Water has tremendous heat capacity. So that's a great example about what can be scheduled in a flexible way. If something is not standard practice doesn't mean it can't be done, or even that it's hard to do. There was no motivation to use any smarts for water heaters because the electricity price was flat, or the price was on a fixed schedule (timers and night heating of water, was done in the eighties here already).

Broken_Hippo 6y ago
It doesn't matter how much it costs to store water. It costs money to heat the water, and that's what you have to pay attention to. This is much harder to work around as you don't have much choice when you use a hot water. Hot waters don't just store cold water in the tank to be heated when electricity prices are low. Instead, it'll start heating after you shower, for example. I am in an apartment: I have a small water heater - I easily run out of water taking a shower if I stick around too long. There are two people in the house, and if we both want to shower in one day, the hot water . That way, I have hot water to do dishes and someone can take a shower in evening. I'm happy the water heater for the washer is separate, but again, it heats when the temperature dips and doesn't keep the water cold until electricity is cheap. Even if the hot water heater waited to heat until prices were low, you are going to have water that is not-as-hot if you are the second person taking a shower. This is simply because as the tank empties, cold water is added to the tank. All subsequent hot water will be cooler. I'll add that some folks sweat at night and must take a shower in the morning (I do when hormones act up. Night sweats are no joke). I'm in an apartment: I cannot update the hot water heater. It literally cannot be done for me and millions of others because we cannot replace such things. You'd have to mandate landlords do improvements, and even then, it'll be years before it is all upgraded. I'd argue that the real answer is to go with tankless heaters in this case: It isn't that you'll be spending money when the electricity is cheap, but you'd use less overall for the actual heating of water.
- pbhjpbhj 6y ago
  Way back when we had immersion water heater with a big insulated tank in a cupboard in the house (a was common in UK then) we'd switch the heater on when we needed it. An hour before having a bath say. Where has is available most people have Combi boilers in the UK, very little or no storage, instant hot water in demand. The idea would be that you notice the electric price is negative (or a control system 'notices' for you) and turn your immersion heater on. The water retains enough heat you have plenty of time to use that water. If we have excess solar this is an inefficient but easy way to slurp it up. Hydroelectric pumped storage would probably be better but grid capacity for that seems low.
- Gravityloss 6y ago
  These are technologically simple problems.
  - ryathal 6y ago
    The solutions are simple, but the implementation is not. A lot of places don't have room for a water heater to store a larger amount of hotter water in order to load shift. furthermore, it's not guaranteed that electricity prices will cause any savings or provide a similar reliability of hot water.
    - Gravityloss 6y ago
      And not every place has to do it. Most houses have plenty of room for bigger and more complex water heaters. Many of those apartment complexes that use centralized ones have room as well. The whole thread was started on the premise that "hot water is an especially hard problem for load shifting, because people have to get hot water immediately" - while the case is the opposite - because hot water is very easy to store.

Broken_Hippo 6y ago

It doesn't matter how much it costs to store water. It costs money to heat the water, and that's what you have to pay attention to. This is much harder to work around as you don't have much choice when you use a hot water. Hot waters don't just store cold water in the tank to be heated when electricity prices are low. Instead, it'll start heating after you shower, for example. I am in an apartment: I have a small water heater - I easily run out of water taking a shower if I stick around too long. There are two people in the house, and if we both want to shower in one day, the hot water . That way, I have hot water to do dishes and someone can take a shower in evening. I'm happy the water heater for the washer is separate, but again, it heats when the temperature dips and doesn't keep the water cold until electricity is cheap. Even if the hot water heater waited to heat until prices were low, you are going to have water that is not-as-hot if you are the second person taking a shower. This is simply because as the tank empties, cold water is added to the tank. All subsequent hot water will be cooler. I'll add that some folks sweat at night and must take a shower in the morning (I do when hormones act up. Night sweats are no joke). I'm in an apartment: I cannot update the hot water heater. It literally cannot be done for me and millions of others because we cannot replace such things. You'd have to mandate landlords do improvements, and even then, it'll be years before it is all upgraded. I'd argue that the real answer is to go with tankless heaters in this case: It isn't that you'll be spending money when the electricity is cheap, but you'd use less overall for the actual heating of water.

pbhjpbhj 6y ago
Way back when we had immersion water heater with a big insulated tank in a cupboard in the house (a was common in UK then) we'd switch the heater on when we needed it. An hour before having a bath say. Where has is available most people have Combi boilers in the UK, very little or no storage, instant hot water in demand. The idea would be that you notice the electric price is negative (or a control system 'notices' for you) and turn your immersion heater on. The water retains enough heat you have plenty of time to use that water. If we have excess solar this is an inefficient but easy way to slurp it up. Hydroelectric pumped storage would probably be better but grid capacity for that seems low.
Gravityloss 6y ago
These are technologically simple problems.
- ryathal 6y ago
  The solutions are simple, but the implementation is not. A lot of places don't have room for a water heater to store a larger amount of hotter water in order to load shift. furthermore, it's not guaranteed that electricity prices will cause any savings or provide a similar reliability of hot water.
  - Gravityloss 6y ago
    And not every place has to do it. Most houses have plenty of room for bigger and more complex water heaters. Many of those apartment complexes that use centralized ones have room as well. The whole thread was started on the premise that "hot water is an especially hard problem for load shifting, because people have to get hot water immediately" - while the case is the opposite - because hot water is very easy to store.