Thermostatic mixing valves: mounting orientation and safety concerns

[RustyShackleford]

I plan to install a Honeywell-Residio thermostatic mixing valve (model AM101-SB-1LF) on a 50gal conventional electric water heater in our vacation house, in order to make more usable hot water available to the 3 bathrooms (4 bedrooms). I've got a couple of concerns ...

1. First, because of the existing plumbing, I'd like to install it with the tempered water outlet pointing upwards; I'm confused about whether this is acceptable, as the instructions are confusing (https://digitalassets.resideo.com/damroot/Original/10014/62-3075EFS.pdf). The paragraph on the lower-right of the first page says "can be installed in any position consistent with the intended use" but then "for domestic hot water supply, the valve must be installed as shown in Fig. 1" and Fig.1 shows the thing oriented with the outlet pointing sideways and the hot and cold coming in from the bottom and top (it's also showing a recirculation system, which I don't have).

2. How fool-proof is the anti-scalding technology ? Especially as the house will be rented a good bit, and small children present when we are using it, I'm concerned about setting the water heater as high as 160. Of course, even 140 gives me a third again as much hot water - if I understand correctly, assuming the incoming cold water is at 60 degrees, since (140-60)/(120-60) = 1.33.

 

[Breplum]

The valve can be oriented in any direction, there is no gravitational influence to worry about. They are very reliable.

It tempers the outgoing water, but is not anti-scald. Always add a thermometer to the installation to allow for accurate adjustments.
The ASSE 1017 standard states that when used, "They should be supplemented by a point of use device to control final temp to fixture".
In other words, you should have an anti-scald shower valve, which all modern pressure balancing or thermostatic shower valves have.
As far as faucets, in residential settings, the additional protection is not legally required and virtually never done.

 

[Sponsor]

 

[Terry]

I really like this one for water heaters, a super easy installation.

The one below is not my install, but does show a different way.

This one under the bathroom sink for the soaking tub.

 

[Terry]

2. How fool-proof is the anti-scalding technology ? Especially as the house will be rented a good bit, and small children present when we are using it, I'm concerned about setting the water heater as high as 160. Of course, even 140 gives me a third again as much hot water - if I understand correctly, assuming the incoming cold water is at 60 degrees, since (140-60)/(120-60) = 1.33.

I have installed quite a few, so that the water heater could be turned up but then safely put out water at 120. It's a big help for filling that bathtub or squeezing in an extra shower or two.

 

[RustyShackleford]

The valve can be oriented in any direction, there is no gravitational influence to worry about. They are very reliable.

That's what I suspected, thanks for confirming.

It tempers the outgoing water, but is not anti-scald. Always add a thermometer to the installation to allow for accurate adjustments.
The ASSE 1017 standard states that when used, "They should be supplemented by a point of use device to control final temp to fixture".
In other words, you should have an anti-scald shower valve, which all modern pressure balancing or thermostatic shower valves have.
As far as faucets, in residential settings, the additional protection is not legally required and virtually never done.

So you're saying this protection might be built into my existing shower valves ? How can I tell ?

The literature for the valve (I've already purchased) seems to say it IS anti-scald, including the sentence "Designed to prevent scalding water and legionella bacteria growth by storing water at 140° F and higher, but delivering safe and comfortable water temperatures out of the faucet up to 120° F."