3 ms·

On a FIRST robot, we needed something similar. There's "full reverse", "full forward" and "I need fine control", and the original mapping of joystick to wheel m

On a FIRST robot, we needed something similar. There's "full reverse", "full forward" and "I need fine control", and the original mapping of joystick to wheel motors was linear. It didn't work well for "fine control". We ended up with motor = joystick³ (or some other odd, greater than 1 power; it might have been ⁵). Then you fix, via coefficients, the endpoints of the equation such that the lowest joystick value hits the full-reverse motor setting, and vice versa for forward. The exponent dampens the curve near zero, so there's more "joystick space" spent on the very slow speeds for the fine control, but the operator can still ask for max speed if they want it. (With joysticks, you also have to deadzone the middle, as "operator has centered the joystick" will sometimes report joystick values of 1 or -1, instead of 0. Or buy a better joystick.) I'm not 100% sure I'd apply this to a shower: max hot on my shower is hot, I don't usually ever want it. And I wouldn't want to scald someone. For a long while, our shower was not the typical tiny goldilocks zone surrounded by ice and lava: … it never really got above "lukewarm", even at max. We had the shower valve replaced and it works better now. (And, apparently, as I learned, there's a mixing valve at the hot water heater: i.e., the hot to the shower is not direct from the water heater, like I had imagined. We raised the temp there, slightly.)

pc86 4y ago
When my wife and I met she lived in an apartment with an amazing shower. The pressure was good but the temperature was fantastic. I had never had an apartment shower with water that got so hot. I barely even went half-way on the knob before I was turning it down. I asked about it and her response was "oh yeah I complained to my dad and he looked at the heater, there was something on it that he broke off." Turns out there was some piece of plastic or something put on by the landlord to limit the top temperature of the water, so he took it off. It didn't keep the hot water from running out but when you had it, it was great.
waste_monk 4y ago
>(And, apparently, as I learned, there's a mixing valve at the hot water heater: i.e., the hot to the shower is not direct from the water heater, like I had imagined. We raised the temp there, slightly.) When we changed from instant hot water to water tank + heat pump, the guy said the tempering valve was a safety thing (IIRC ours was set to 60 degrees Celsius by default, but could go up or down about 10 degree either way). That is, if you accidentally step in the shower with only hot water on you'll still hurt yourself but the damage will be limited to "strong profanity and aloe vera" instead of "you've won a stay in the burn ward". Although saying this, I did a quick bit of research and found that 60 may still be too high [1]. I have an IR thermometer so I think I'll measure the temperature of my shower (after any loss from pipes etc.) and see if the tempering valve needs adjusting down. [1] mild nsfw - image of scalded foot https://whywait.com.au/a-serious-hot-water-burn-occurs-in-one-second/ https://whywait.com.au/a-serious-hot-water-burn-occurs-in-on...
- deathanatos 4y ago
  "Safety" is also what my guy said. The problem is that in isolation the answer doesn't make any sense: why should I be heating water up to then re-mix cold water? Is that not a waste of energy? The fuller answer, I think, is that the "raw" hot line additionally goes towards uses that can take scalding water, one or more of the dishwasher and the laundry, depending on whether you have either or both of those in your dwelling. (I hadn't thought of those, since my concern was on the shower. I also can't see the piping, in my place, so it was a black box of sorts.) For uses that might interact with a human, then it's a safety thing, then it makes sense to do the mix with cold. (I believe the other line, the shower bound one, is called the "tempered hot" line.) My guy also refused to raise it too much, or disable it altogether, citing codes and that it couldn't exceed like 140℉ or so. Which was fine, really, since I was asking for it to exceed 95℉…
  - morepork 4y ago
    Storing the water at a higher temperature effectively increases the capacity of the tank. Also the stored hot water has to be above a certain level (~60 degrees) at least some of the time otherwise it won't prevent any bugs growing in it.
    - waste_monk 4y ago
      Yep... particularly Legionella Pneumophila and friends which can cause Legionnaire's disease. I was taught as a child NEVER to use a hot shower from a water tank or drink warm water from the tap after a sustained power outage until the tank has had time to come back up to it's normal temperature... Legionnaire's can straight-up kill you via pneumonia.

pc86 4y ago

When my wife and I met she lived in an apartment with an amazing shower. The pressure was good but the temperature was fantastic. I had never had an apartment shower with water that got so hot. I barely even went half-way on the knob before I was turning it down. I asked about it and her response was "oh yeah I complained to my dad and he looked at the heater, there was something on it that he broke off." Turns out there was some piece of plastic or something put on by the landlord to limit the top temperature of the water, so he took it off. It didn't keep the hot water from running out but when you had it, it was great.

waste_monk 4y ago

>(And, apparently, as I learned, there's a mixing valve at the hot water heater: i.e., the hot to the shower is not direct from the water heater, like I had imagined. We raised the temp there, slightly.) When we changed from instant hot water to water tank + heat pump, the guy said the tempering valve was a safety thing (IIRC ours was set to 60 degrees Celsius by default, but could go up or down about 10 degree either way). That is, if you accidentally step in the shower with only hot water on you'll still hurt yourself but the damage will be limited to "strong profanity and aloe vera" instead of "you've won a stay in the burn ward". Although saying this, I did a quick bit of research and found that 60 may still be too high [1]. I have an IR thermometer so I think I'll measure the temperature of my shower (after any loss from pipes etc.) and see if the tempering valve needs adjusting down. [1] mild nsfw - image of scalded foot https://whywait.com.au/a-serious-hot-water-burn-occurs-in-one-second/ https://whywait.com.au/a-serious-hot-water-burn-occurs-in-on...

deathanatos 4y ago
"Safety" is also what my guy said. The problem is that in isolation the answer doesn't make any sense: why should I be heating water up to then re-mix cold water? Is that not a waste of energy? The fuller answer, I think, is that the "raw" hot line additionally goes towards uses that can take scalding water, one or more of the dishwasher and the laundry, depending on whether you have either or both of those in your dwelling. (I hadn't thought of those, since my concern was on the shower. I also can't see the piping, in my place, so it was a black box of sorts.) For uses that might interact with a human, then it's a safety thing, then it makes sense to do the mix with cold. (I believe the other line, the shower bound one, is called the "tempered hot" line.) My guy also refused to raise it too much, or disable it altogether, citing codes and that it couldn't exceed like 140℉ or so. Which was fine, really, since I was asking for it to exceed 95℉…
- morepork 4y ago
  Storing the water at a higher temperature effectively increases the capacity of the tank. Also the stored hot water has to be above a certain level (~60 degrees) at least some of the time otherwise it won't prevent any bugs growing in it.
  - waste_monk 4y ago
    Yep... particularly Legionella Pneumophila and friends which can cause Legionnaire's disease. I was taught as a child NEVER to use a hot shower from a water tank or drink warm water from the tap after a sustained power outage until the tank has had time to come back up to it's normal temperature... Legionnaire's can straight-up kill you via pneumonia.