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A manifesto on shower temperature control

benholmen.com

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Re: A manifesto on shower temperature control

#11

Post by Gordonjcp »

gwern wrote: post #10
PaulHoule wrote: post #2

I think the current ones are the way they are because the input temperature is not well controlled. I live in an old farmhouse where the cold water gets really cold in the winter and for years we've had a tankless water heater that has never worked that well but lately has gotten full of scales. We haven't tried descaling it because we're concerned that we'll kill it in the process of descaling it and won't try it un…

Or to put it another way: Spolsky said that users don't use 90% of the features in any app; unfortunately, they each don't use a different 90%. You don't use 90% of the shower faucet ratio range; unfortunately, each house doesn't use a different 90% of the ratio range...

Thing is, that 90% of the range is going to mean that you and I pick a different range from "hottest" to "coldest", right?

So it wouldn't be beyond the wit of man to fit a couple of setscrews, possibly accessible by popping the knob off, to set the "low" and "high" stops for the thermostat in the shower valve, right?

You'd think, eh...?

Re: A manifesto on shower temperature control

#12

Post by trynewideas »

achenatx wrote: post #9
stdbrouw wrote: post #6

Earlier quoted context omitted.

Huh? Regular thermostatic valves do not provide perfect regulation but they do in fact provide a fairly stable output temperature regardless of cold and hot water temperature, by entirely mechanical means. I have a cheap IKEA shower control and output temp is stable for the full duration of my shower even though cold nor hot water supply is stable due to a shower drain heat recovery unit. The article is mainly about…

you can change the top end by lowering the temperature of your hot water heater. We have ours set at 120. Using a lower hot water temperature is a way to give you a wider range of useful temperatures. In texas during the summer we often take showers with no hot water (or very little hot water).

This isn't always feasible depending on the location, age, and type of water heater, and how many things with different temperature needs are connected to the same water heater.

A tankless water heater with a feeder pump, dedicated to bathroom use and with a bathroom-installed remote control, makes this trivial. It's probably also more efficient, easier to use, and (vs. thermostatic valves) about as easy and maybe also cheaper to implement than any fussing with valves.

A 30-year-old tank heater in a basement that needs a wrench to adjust a temperature that won't meaningfully change in a 2nd-floor bathroom for another half-hour, and also has to serve a dishwasher and clothes washer that might also run at higher temperatures at the same time, can't swing this as easily, or at all.

Re: A manifesto on shower temperature control

#13

Post by Someone »

achenatx wrote: post #9
stdbrouw wrote: post #6

Earlier quoted context omitted.

Huh? Regular thermostatic valves do not provide perfect regulation but they do in fact provide a fairly stable output temperature regardless of cold and hot water temperature, by entirely mechanical means. I have a cheap IKEA shower control and output temp is stable for the full duration of my shower even though cold nor hot water supply is stable due to a shower drain heat recovery unit. The article is mainly about…

you can change the top end by lowering the temperature of your hot water heater. We have ours set at 120. Using a lower hot water temperature is a way to give you a wider range of useful temperatures. In texas during the summer we often take showers with no hot water (or very little hot water).

> you can change the top end by lowering the temperature of your hot water heater. We have ours set at 120

I’m not sure that’s a good idea. 120F is in the danger zone for Legionnaires' disease. https://en.wikipedia.org/wiki/Legionnaires%27_disease#Preven...:

“Keep water temperature either above or below the 20–50 °C (68–122 °F) range in which the Legionella bacterium thrives.”

Re: A manifesto on shower temperature control

#14

Post by unethical_ban »

joezydeco wrote: post #3

These devices exist. You just don't want to pay for them. https://www.kohler.com/en/products/showers/shop-shower-trims... What you have in your shower is a cheaper anti-scald valve that just prevents super huge spikes in water temperature when the input pressure changes (i.e. your wife flushes the toilet). Like PaulHoule says, you need monitoring of input and output temps to do that. And that's technically possible,…

I feel like a mechanical version could be made which has a separate gear ratio for the middle of the operating spectrum.

Alternatively, for the traditional "hot/cold knobs" function, I don't see why a third pressure knob couldn't be added.

I could leave the hot and cold knobs turned exactly where I want them to be, with some arbitrary number dial helping for consistency, and I only have to turn the pressure knob to let the water start running.

I shouldn't have to spend $1500 for that.

Re: A manifesto on shower temperature control

#15

Post by _yb2s »

I prefer cold showers, and have the opposite complaint. Most valves are over-optimized for 'normal' shower temp ranges, and still mix in a lot of hot water even on the coldest setting, which makes taking a really cold shower impossible.

Re: A manifesto on shower temperature control

#16

Post by convolvatron »

unethical_ban wrote: post #14
joezydeco wrote: post #3

These devices exist. You just don't want to pay for them. https://www.kohler.com/en/products/showers/shop-shower-trims... What you have in your shower is a cheaper anti-scald valve that just prevents super huge spikes in water temperature when the input pressure changes (i.e. your wife flushes the toilet). Like PaulHoule says, you need monitoring of input and output temps to do that. And that's technically possible,…

I feel like a mechanical version could be made which has a separate gear ratio for the middle of the operating spectrum. Alternatively, for the traditional "hot/cold knobs" function, I don't see why a third pressure knob couldn't be added. I could leave the hot and cold knobs turned exactly where I want them to be, with some arbitrary number dial helping for consistency, and I only have to turn the pressure knob to l…

its not really gears? I assume its some kind of bi-metal strip. if so, you would just need to change the shape of a cam (?)

Re: A manifesto on shower temperature control

#17

Post by retrac »

Ah yes, showers that have frigid, cold, and scalding settings, and not much in the way of warm.

This is is usually because the hot supply is under relatively less pressure, going through a tank and more pipes. So, nice and warm means hot is almost fully open and cold almost fully closed, to get an equal mix of both. Very little room to work with.

The right flow restrictor on the cold supply will make midway an even mix, and so more of the dial is useful. Very much worth the $10 the next time you have access to the plumbing.

Re: A manifesto on shower temperature control

#18

Post by Kim_Bruning »

stdbrouw wrote: post #6
joezydeco wrote: post #3

These devices exist. You just don't want to pay for them. https://www.kohler.com/en/products/showers/shop-shower-trims... What you have in your shower is a cheaper anti-scald valve that just prevents super huge spikes in water temperature when the input pressure changes (i.e. your wife flushes the toilet). Like PaulHoule says, you need monitoring of input and output temps to do that. And that's technically possible,…

Huh? Regular thermostatic valves do not provide perfect regulation but they do in fact provide a fairly stable output temperature regardless of cold and hot water temperature, by entirely mechanical means. I have a cheap IKEA shower control and output temp is stable for the full duration of my shower even though cold nor hot water supply is stable due to a shower drain heat recovery unit. The article is mainly about…

Are cheap thermostatic shower mixer controls not so common outside middle-of-europe?

This is the one with one grip that lets you set the temperature, and the other sets the flow rate.

It'll (try to) hold the output temperature steady even if the input temperature varies a bit.

Re: A manifesto on shower temperature control

#19

Post by retrac »

unethical_ban wrote: post #14
joezydeco wrote: post #3

These devices exist. You just don't want to pay for them. https://www.kohler.com/en/products/showers/shop-shower-trims... What you have in your shower is a cheaper anti-scald valve that just prevents super huge spikes in water temperature when the input pressure changes (i.e. your wife flushes the toilet). Like PaulHoule says, you need monitoring of input and output temps to do that. And that's technically possible,…

I feel like a mechanical version could be made which has a separate gear ratio for the middle of the operating spectrum. Alternatively, for the traditional "hot/cold knobs" function, I don't see why a third pressure knob couldn't be added. I could leave the hot and cold knobs turned exactly where I want them to be, with some arbitrary number dial helping for consistency, and I only have to turn the pressure knob to l…

A cheap valve between the hot/cold valves and the bath faucet or showerhead can provide that.

Unfortunately, single-handle mixer valves aren't usually designed to have their output blocked under pessure like that. So that's when it starts getting expensive and specialized. But with traditional separate hot/cold valves, it works fine.

Re: A manifesto on shower temperature control

#20

Post by AnthonBerg »

I have a kind of powerful dirt bike. People put “throttle cams” on them for this same reason. Usually you want small adjustments within the lower range of power. When you want the majority of power you usually want close to all of it.

Throttle cams are basically an off-center circle. At lower throttle you’re pulling a smaller circle and the throttle moves less. Then when the throttle is opened up you’re pulling a bigger circle.

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