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A manifesto on shower temperature control

benholmen.com

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Re: A manifesto on shower temperature control

#131

Post by jameshart »

Much of the confusion in this thread comes down to the fact that in the US, the standard shower valve is a 'pressure-balanced' valve, which allows you to select a flow-ratio between hot and cold feeds, but does not in itself maintain any particular temperature - it just ensures that in the event of pressure changes on one or other feed, the overall mix is maintained (preventing temperature spikes if someone flushes a toilet).

Whereas in many other parts of the world, the standard shower valve is a 'thermostatic mixing valve', which allows you to select a temperature, and balances the inputs to achieve that desired temperature mark.

Note that if you go to, say, HomeDepot.com, and look at shower faucets, you will not find thermostatic mixing valves. Only pressure balanced. The only thermostatic component in conventional american shower valves is an anti-scald-cutoff. Thermostatic valves do exist, but they're not the ones that are bundled into showers and that therefore get employed by the average landlord who is grabbing the cheap standard parts off the shelf. Thermostatic is a premium option, and not one that even crops up in the search result filters for showers.

So most Americans have simply no idea that thermostatic valves are a thing.

Whereas if you go to, say, diy.com (which is the store of B&Q, an equivalent store in the UK), and look up showers, you will find all the basic 'mixer showers' have thermostatic valves.

Re: A manifesto on shower temperature control

#132

Post by japaneseminisub »

dsfyu404ed wrote: post #73
gorgoiler wrote: post #45

As a friendly heads up to anyone exploring this space — temperature control is a complex dynamic between many components, chiefly the mixing valve, any local thermostatic dampers in the valve (rarer, but definitely a feature of high end mixers), and the source of hot water itself . Mixer taps are not simply mixing hot water at temperature H and cold water at temperature C. The temperature H which your hot water sourc…

All this additional complexity, while great for getting an engineer circle jerk going, is mostly irrelevant if you are using the dial for coarse adjustment and dialing it in by feel and if your shower is shorter than the time it takes to make your hot water supply change temp a meaningful amount. Shower valves were literally two dumb valves for the first 100yr and they worked fine.

Absolutely.

I adjust my shower based on feel, sometimes I want hot, sometimes I want cold. Then I just turn then temperature knob.

I don't think I will ever want an explicitly 38°C shower.

Re: A manifesto on shower temperature control

#133

Post by fomine3 »

nwiswell wrote: post #77
diggernet wrote: post #65

Earlier quoted context omitted.

You don't need a computer, or even electricity. Thermostatic shower valves are 100% mechanical, and work beautifully. There are models available that will automatically compensate for both temperature and pressure changes, keeping the output temperature constant.

Alright, but can I run Doom on a thermostatic shower valve?

Let's run Half-Life 2

Re: A manifesto on shower temperature control

#135

Post by giantg2 »

jameshart wrote: post #131

Much of the confusion in this thread comes down to the fact that in the US, the standard shower valve is a 'pressure-balanced' valve, which allows you to select a flow-ratio between hot and cold feeds, but does not in itself maintain any particular temperature - it just ensures that in the event of pressure changes on one or other feed, the overall mix is maintained (preventing temperature spikes if someone flushes a…

I think a lot of the US fixtures don't even have compatible thermostatic valves. You'd have to get a complete replacement fixture, not just a valve/cartridge/insert.

Re: A manifesto on shower temperature control

#136

Post by giantg2 »

josephg wrote: post #102
Macha wrote: post #96

Earlier quoted context omitted.

This is also the case for electric showers though, where the shower itself contains the heating element and heats its own water, rather than taking arbitrary feeds of hot and cold water.

The shower doesn't need an internal heating element. All you need is an electric control system, which dynamically monitors the temperature coming out of the shower head and constantly adjusts the mix toward a set temperature. I have a feeling these have existed for a long time in Japan.

You don't even need an electronic thermostat. You have manual thermostatic valves that do the same thing. I believe it has to do with the thermal properties and mechanical interface of a couple pieces of metal. As they expand or contract, it adjusts the mix to maintain the temperature set by the position of the handle.

Re: A manifesto on shower temperature control

#137

Post by randombits0 »

giantg2 wrote: post #135
jameshart wrote: post #131

Much of the confusion in this thread comes down to the fact that in the US, the standard shower valve is a 'pressure-balanced' valve, which allows you to select a flow-ratio between hot and cold feeds, but does not in itself maintain any particular temperature - it just ensures that in the event of pressure changes on one or other feed, the overall mix is maintained (preventing temperature spikes if someone flushes a…

I think a lot of the US fixtures don't even have compatible thermostatic valves. You'd have to get a complete replacement fixture, not just a valve/cartridge/insert.

You could define the desired characteristics in the shape of a curved hole within ceramic disks, such as the type commonly used shower faucets currently.

Re: A manifesto on shower temperature control

#138

Post by kps »

Someone wrote: post #13
achenatx wrote: post #9

Earlier quoted context omitted.

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.”

> the 20–50 °C (68–122 °F) range

That's clearly a case of conversion results being given unwarranted precision.

Re: A manifesto on shower temperature control

#140

Post by mhandley »

jameshart wrote: post #131

Much of the confusion in this thread comes down to the fact that in the US, the standard shower valve is a 'pressure-balanced' valve, which allows you to select a flow-ratio between hot and cold feeds, but does not in itself maintain any particular temperature - it just ensures that in the event of pressure changes on one or other feed, the overall mix is maintained (preventing temperature spikes if someone flushes a…

Yes, our thermostatic valve has around 270 degrees of travel on the temperature dial (which is separate from the water flow dial). Of those 270 degrees, it takes about 140 degrees to go from my preferred temperature to my wife's preferred temperature. With that large a range I can just turn it to roughly the right place before turning the water on and it's always just the right temperature. This isn't the cheapest valve (about £190) but I think many cheaper thermostatic valves are probably just as good.

Ours is one of these: https://www.amazon.co.uk/gp/product/B06XNZHZGJ/

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