Instantaneous water heaters and required service

[kwired]

I think their real utility is in bathrooms for the sink, usually some public restroom where you can have short periods of high demand and long lulls. Think movie theaters and the like. A storage tank large enough would be huge and standby losses might be significant, whereas the demand at each individual sink would be relatively low, but pretty constant when the theater lets out, for 20-30 minutes.

I agree, and at same time in a place where there is longer demand periods that is also where a storage tank that allows some pre conditioning to happen may lessen wattage needed. For occasional hand washing you possibly have enough water in supply pipes that has warmed up to near room temp to get desired output temp, but if demand has been enough that much cooler water is now entering you may not be able to achieve desired temp at same flow rate anymore. Maybe in the movie theater situation you don't care so much as long as it isn't too cold. Hand wash sink in food prep area, health care, etc. some regulatory party might want to see a certain temperature with some consistency?

 

[gadfly56]

I agree, and at same time in a place where there is longer demand periods that is also where a storage tank that allows some pre conditioning to happen may lessen wattage needed. For occasional hand washing you possibly have enough water in supply pipes that has warmed up to near room temp to get desired output temp, but if demand has been enough that much cooler water is now entering you may not be able to achieve desired temp at same flow rate anymore. Maybe in the movie theater situation you don't care so much as long as it isn't too cold. Hand wash sink in food prep area, health care, etc. some regulatory party might want to see a certain temperature with some consistency?

The difficulties in delivering hot water are two-fold; water wasted waiting for the hot water to make it from storage to the tap, and the heat wasted as the water between the tap and the tank cools down, creating the next slug of cold water for the next user. Point-of-use water heating solves both problems at once. Clearly, it requires good intel on usage patterns to map out the best strategy that minimizes water wasted and energy dissipated to no good use.

 

[LarryFine]

Point-of-use water heating solves both problems at once. Clearly, it requires good intel on usage patterns to map out the best strategy that minimizes water wasted and energy dissipated to no good use.

Then I would ideally have two: one in the basement under my kitchen sink, and one in the attic above the master bath.