# Does this variant of a thermostatic valve exist as a product I can buy?

**URL:** <https://boards.straightdope.com/t/does-this-variant-of-a-thermostatic-valve-exist-as-a-product-i-can-buy/1017995>\
**Category:** Factual Questions\
**Created:** [May 7, 2025, 5:49am UTC](https://boards.straightdope.com/t/does-this-variant-of-a-thermostatic-valve-exist-as-a-product-i-can-buy/1017995 "2025-05-07T05:49:38Z")\
**Posts on this page:** 7\
**Page:** 2

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**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\
**Post date:** [May 8, 2025, 8:53pm UTC](https://boards.straightdope.com/t/does-this-variant-of-a-thermostatic-valve-exist-as-a-product-i-can-buy/1017995/21 "2025-05-08T20:53:00Z")

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Skip the hit water tank and go with a suicide shower

> **[Electric shower](https://en.wikipedia.org/wiki/Electric_shower)**
>
> An electric shower or electric shower head are self-heating shower heads that use an immersion heater which is turned on with the flow of water. A group of separate electric heating elements can be switched to offer different heating levels. They are specialized point-of-use tankless water heaters and are widely used in some countries.
> Invented in Brazil in the 1930s due to a lack of central gas distribution and used frequently since the 1940s, the electric shower is a home appliance often seen ...

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**Author:** ![Lucas\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lucas_jackson/32/303_2.png) [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)\
**Post date:** [May 8, 2025, 9:28pm UTC](https://boards.straightdope.com/t/does-this-variant-of-a-thermostatic-valve-exist-as-a-product-i-can-buy/1017995/22 "2025-05-08T21:28:07Z")

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In the US market, the two main types of shower valves are manual mixer valves and thermostatically controlled valves. Manual mixer valves require you to manually adjust handles to control the temperature, while thermostatic valves maintain a set temperature.

Manual Mixer Valves:  
• These valves use separate handles for hot and cold water, allowing you to mix the water to achieve your desired temperature.  
• They require constant adjustment to maintain the desired temperature, especially if there are fluctuations in hot or cold-water pressure.

Thermostatically Controlled Valves:  
• These valves use a thermostatic cartridge to automatically mix the hot and cold water, maintaining a consistent temperature.  
• They offer a more stable and safer shower experience, especially for families with children or elderly members.

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**Author:** ![echoreply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/echoreply/32/3641_2.png) [@echoreply](https://boards.straightdope.com/u/echoreply)\
**Post date:** [May 8, 2025, 11:12pm UTC](https://boards.straightdope.com/t/does-this-variant-of-a-thermostatic-valve-exist-as-a-product-i-can-buy/1017995/23 "2025-05-08T23:12:00Z")

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> [@Darren\_Garrison](#):
>
> Skip the hit water tank and go with a suicide shower

My host when I spent a lot of time in the UK had one called the Power Shower, or something like that. The water there was so hard that it would clog up the shower head, creating too much back pressure, so the water spent too long in contact with the heating element, and would get much too hot even on the lowest setting.

We would descale the shower head about once a week to keep the temperature at a reasonable level.

When it worked it was great. Endless hot water on a damp and cold English morning was very nice.

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**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\
**Post date:** [May 8, 2025, 11:24pm UTC](https://boards.straightdope.com/t/does-this-variant-of-a-thermostatic-valve-exist-as-a-product-i-can-buy/1017995/24 "2025-05-08T23:24:47Z")

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> [@echoreply](#):
>
> When it worked it was great. Endless hot water on a damp and cold English morning was very nice.

I don’t really understand how this could be true. A low-flow showerhead is about 2 gpm, or 125 cc/s. The beefiest electric showerheads I can find are 7.5 kW, which will heat the water by 14.5 C. But if the tap water is 15 C, that’s \<30 C, which is barely lukewarm.

I guess you could get a super low-flow showerhead, like 1 gpm, but those make for a kinda crappy shower.

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**Author:** ![echoreply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/echoreply/32/3641_2.png) [@echoreply](https://boards.straightdope.com/u/echoreply)\
**Post date:** [May 8, 2025, 11:39pm UTC](https://boards.straightdope.com/t/does-this-variant-of-a-thermostatic-valve-exist-as-a-product-i-can-buy/1017995/25 "2025-05-08T23:39:34Z")

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> [@Dr.Strangelove](#):
>
> I don’t really understand how this could be true. A low-flow showerhead is about 2 gpm, or 125 cc/s. The beefiest electric showerheads I can find are 7.5 kW, which will heat the water by 14.5 C. But if the tap water is 15 C, that’s \<30 C, which is barely lukewarm.

Looks like I misunderstood how it works. The “endless hot water” was probably just a large hot water tank for the whole building. The power shower is some sort of pump and thermostatic valve.

All I do know is the think about the scale building up in the shower head was real, but it must have been some interaction with the thermostatic valve caused by the restricted flow.

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**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\
**Post date:** [May 8, 2025, 11:44pm UTC](https://boards.straightdope.com/t/does-this-variant-of-a-thermostatic-valve-exist-as-a-product-i-can-buy/1017995/26 "2025-05-08T23:44:12Z")

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Ahh, that makes more sense. The electric showerheads are real and do provide “endless” hot water. I’ve just never been under the impression that they’re especially luxurious. Just not enough juice to have steaming-hot water _and_ a high flow rate. Well, maybe someone will wire in 3-phase power at 15 kW or so…

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**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\
**Post date:** [May 8, 2025, 11:44pm UTC](https://boards.straightdope.com/t/does-this-variant-of-a-thermostatic-valve-exist-as-a-product-i-can-buy/1017995/27 "2025-05-08T23:44:55Z")

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> [@Napier](#):
>
> > [@Saffer](#):
> >
> > the shower would slowly start to get cold at some point
> 
> There seems to be doubt in this thread that the temperature decline can be gradual enough to allow predicting how much time one has left. Perhaps this varies quite a lot between homes and systems. It’s gradual and predictable in my house, FWIW.

Mine, too. Also, i wish i could get a thermostatic calculate that would maintain a temperature. I asked the builder for one, having used them in Japan and Europe, and he just gave me something that has separate volume and temp controls. But the temp control is just x% hot, and as the hot water cools, i slide it up until it’s only drawing “hot” water.

And while the brand new washing machine in my basement can heat water, it has a hot water input as well as a cold water input, and definitely uses the hot water from the tap.

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