This on demand heater appears to have a mixing valve installed, which seems to be pointless. This would allow the cold inlet to enter the mixing valve as well as the water heater. I dont see how it could really be a problem, but wouldnt this be completely unnecessary, as you would just change the temp of the water heater? Or is this a new code that I am not aware of?
Thanks
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Was it actually a whole house tankless or being used for a bath group with a stand alone tub? They might have placed the tempering valve to meet the requirements of IRC P2713.3.
I’ve seen this done on tank water heaters to limit the whole house for safety reasons. However typically I find them on stand alone tubs so the tank, or tankless, can provide higher temps as desired at other locations or to compensate for temp variations at farther fixtures.
Yes, that is typically where I see them as well. Some jurisdictions require them at soaking tubs. But rhis is a whole home water heater, and it has a digital temp adjustment, thx
Can’t help with your question and am looking forward to what the resident plumber @mwilles has to say.
I am curious if the enclosure had a cover though. Judging from the wasp nests and feces at the bottom, I can only imagine what other pest have made it into the opening around the pipe and into the wall.
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Maybe not Daniel. I suspect the owner wanted to maintain good water volume at the hot taps.
Tankless water heater heat exchangers are constructed of many short pieces of pipe and lots of elbows. Often the pipe diameter is also reduced to shorten heating time. It’s a water volume killer.
Solution for good hot water volume may be to crank up the tankless to 140F and install a mixing valve. Not a bad idea for a home that may have low water pressure.
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That’s what I did at my one house and it worked really good.
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I’m surprised there’s no bypass or service valves installed, especially for flushing the unit.
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Look at step 11, these units do not require annual maintenance.
Thanks martin, I did actually put in my report that it needed to be serviceable, and have a flex line installed for removal. Now I will update the client, maybe I was looking at the wrong manual…
Funny you say that, because the volume was greatly impacted when bathtub and faucets were on. And when both bathtubs were on, the second bath had almost no water flow at all. (pics of tub are with and without master tub going) The instructions say it is good up to 2 bath, which this home was.
This was the Tempura plus 24. 3 year old home, water pressure at hose bib was 60
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Thanks for the link, that just means this “design” is disposable, especially with our very hard water, full of scale.
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And thanks for that info… I had a one bath home I inspected a couple weeks ago, and if the tub was on alone, it was 120*. But as soon as I turned on anything else, the temp would drop to about 105*
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