Noritz questions

aliris19April 19, 2012

Hi all -- I've never posted on this forum before but know several of you from kitchens and appliances.

Apologies in advance if I should have been able to glean some or all answers from archives. I looked, didn't see and went for the easy-way: just ask.

I have a Noritz tankless water heater installed over a year now. I've always loved the idea of the thing since long before you could ever even find any for sale here in the States. I don't even care if it never pays itself back; it's just - to me - seemingly so wasteful to keep water stewing forever that this insta-heater seemed to be the obvious only answer for our hot water needs.

However.... I'm not really loving the amount of hot water available. Not in volume, obviously that just keeps coming and coming. But it's not very toasty, what comes out.

So I'm wondering whether there's some error in installation perhaps? It's set as high as it will go, at 125-degrees. I don't know if this is a system-limitation or a jurisdiction one but I don't seem to be able to get the machine to let me input a higher number. It's located literally 5 feet from the shower head as the mosquito-termite might crawl and bore, but probably the pipes have to swoop downward and under the house and back up a bit to the showerhead. Still, it's all on the same, bottom floor, so there just can't be very much tubing in the way. I'm in SoCal so even with zero insulation, shouldn't it stay hotter for the shower?

It's not that it's not hot at all, just not to my taste. I don't know if my hot-shower tastes are untoward; could be...

But I'm wondering whether (a) perhaps there's an installation problem (b) whether there's any way to set the water temperature to higher (c) whether I should try to insulate the pipes, short and relatively unexposed though they be anyway? (d) whether I just have to get used to the cooler water temperature? Is this a compromise people with tankless heaters all accept? Or is there something wrong with my system?

Thanks for any thoughts...

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Here's what you need to do: You need to measure the temperature of the water as it comes out of the bathroom sink faucet. You could be having a problem with the anti-scald feature in the shower.

A more direct way would be to measure the temperature of the pipe as it exits the water heater. In order to do that you would use a digital thermometer (from the drug store if you don't have one) tape the bulb so it's in direct contact with the pipe, and then completely cover that with some rags tied tightly to insulate the tip of the thermometer where it touches the pipe. Then run the hot water for a while.

If you don't see about 125 degrees, then something is wrong.
If you do, but the water in the shower isn't hot (use the thermometer) then I would suspect a mixing valve or an anti-scald valve.

Let us know what you find out.

    Bookmark   April 19, 2012 at 5:58PM
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Wonderful, Jake. Thank you!

I guess it's time to acquire a digital thermometer -- I assume I need a food grade one, not one of those body-temperature ones. Those probably don't even go high enough; if I were 125-degrees, for example, we'd not really have too much need of a thermometer ;)

    Bookmark   April 19, 2012 at 6:53PM
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Sophie Wheeler

It could also be, um, user error. You shouldn't try for super hot water from a tankless to then mix with a lot of cold. You should be able to shower with almost all hot water with just a splash of cold to slightly temper it. If you have nothing but the hot water on in your shower, is it hot enough to shower with without mixing any cold in at all? If so, then you may just be mixing too much cold in. Or your shower valve may be need adjusting or be defective.

    Bookmark   April 19, 2012 at 7:10PM
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Sticking an instant read thermometer under a sink should help you tell what's going on. That said, there is also a service mode for the display that you can scroll through a bunch of registers and see what the leaving water temperature is. Somewhere I have written down how to do that and which register, but I haven't looked at it in 5 years and it may have changed for newer models.

The issue with running the outlet temp at 125F may be that you mix so much cold water that you shut off the tankless based on flow. Our Noritz is set at 105F, and the late-summer cold water temp in ATL is warm enough that our thermostatic shower valve shuts the HW flow down enough about 5 min into a shower that the heater shuts off. Then you get a shot of cold water.

The only other thing that could be a big deal is if your gas line isn't big enough. Dropping in a tankless to replace a tank gas heater without increasing the line size could be a problem. The 199k BTU burner, for example, is probably 2X the size of a tank heater's burner.

I'm not sure how the heater would behave if this were the case.

    Bookmark   April 22, 2012 at 10:16AM
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