tempering valve for hot-water heater (what brand ?)

I'm thinking to install a "tempering" or "mixing" valve on my hot-water heater. This mixes some cold water with the hot water coming out of your hot-water heater (before it flows off to the various hot-water faucets). As I understand it, this his many advantages:

1. You can set your tank to a hotter temperature, thereby effectively having more hot water available, without worrying about scalding. This is my primary motivation, a 50 gallon tank, set to 120-degrees or so, not cutting it with a girlfriend now cohabiting and taking lots of baths.

2. By not having your tank set to a lower temperature, you avoid the risk of Legonnaire's disease.

3. The hot water coming to your faucets is always the same temperature, regardless of where the heater is in its cycle (thermostat hysteresis).

So, my question: what is a good brand/model to get ?

Highbeam said:

Anyway, how about a larger water heater or a second one ?

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The tempering valve seems like a simpler solution. I'm not very far away from enough hot water as it is. And Legonnaire's is a slight concern.

jebatty said:

For many years I've used a Honeywell-Sparco mixing valve on my hot water boiler with up to 190F output to mix down to 100F set-point for the in-floor pex. I think the hottest mixed water from the valve has been about 105F and mixed water temp will dip below 100F as boiler supply drops to something below 120-110F.

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Bummer, I thought these valves could control output closer than a 5-degree range. That's probably not much better than the thermostat hysteresis on a regular storage-tank heater. Oh well, it'd still have the other benefits I listed.

peakbagger said:

FYI, you might want to check your local code, you may need a separate high temperature protection valve in addition to a tempering valve. I have a Honeywell version that is claimed to be a combination version.

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Not gonna be inspected - but I do care about doing the right thing. What exactly does this high-temp protection valve do ?