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Tankless Hot Water Heater Advice

15 years ago

Hi, I have a Noritz N 132 M Hot Water Heater that is about 3 years old, and recently has not been working properly. I can't get it to send hot water to the shower. Its like its not turning on when I turn on the shower, however, sometimes, if I turn on the sink, I can get it to kick on, and then can shower, but that doesn't always work. Any advice would be greatly appreciated!!!!!!

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Comments (4)

aidan_m
15 years ago
0.7 GPM is a pretty high minimum flow rate. If your shower has low pressure, you probably aren't demanding enough hot water to make it kick on. Clean the shower head and the mixing valve if it has an internal screen. You could also set the Noritz to a lower setting, like 110, to demand a greater output volume from the unit.
jake2007
15 years ago
.7 gpm is pretty high and I agree with Aidan, lowering the output temp of the heater to 110 will cause more water to flow through the heater and thus meet the .7 gpm.

That said, it sounds as if this is a more recent problem. If nothing has changed, such as the owner installing a new low-flow shower head, I would look to other problems besides not meeting the min flow rate.

It may be reasonable to have the heater unit flushed. This is normally done with vinegar to remove the hard water mineral buildup. It may improve your situation if scale is causing the flow switch problems.

Let us know how it turns out.
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There isn't an exact answer to your question, it will vary by how hard the water is, and how much you use. What they are doing (or should be doing) is removing the lime buildup in the heater with vinegar. The acid will dissolve the hard water deposits that will eventually clog a tankless. It's about a 10-15 minute flush with vinegar. You can google it and see many videos on how to do it. Three years is about right in your situation. I wouldn't just let it go. Tankless heaters use small heating coils to expose the water to heat quickly. You don't want those passages to clog. You can call around for a good price over the phone. They don't need to come out to give you a quote, this is a basic job.
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So, @For M1, This sounds like a very bad plan. Don't go into a tankless replacement/install without some good planning. Just don't. 1. How hard is your water? Get a hach test kit and find out. Don't guess. 2. Do not buy a "Generic Chinese HWH from Ebay" there's lots of ways that can go wrong. You have no way of knowing it's been certified by various safety agencies including the gas part, the electrical part, lead free, etc. Not to mention warranty or service. 3. You need to know the approximate temp of the cold water in the winter and how much hot water you would use at one time. For example, do two people get ready for work at the same time (two showers). 4. You need to know the BTU input for the water heater. Then you must determine if you have adequate gas supply to the heater - and to the house in total. Don't guess. 5. You must adhere to venting requirements. No creativity here. Otherwise you will go to sleep and not wake up. This is not standard DIY stuff, and I get the impression that you are inclined to guess / take shortcuts / look for cheap hacks. This isn't the project to do that with.
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We installed a gas tankless in 2013. No problems at all. The size & number needed was decided by the company installing our Rinnae brand, which was purchased through Ferguson. Our choice was determined by space considerations. As mentioned, it is helpful to place it close to your kitchen/bathrooms. Our location was not ideal. The size of the gas line had to be increased, adding to the cost. We have no regrets, but moving yours to the garage sounds like a much cheaper option. As previously mentioned, it does not work in a power disruption. It also did not improve the look of the laundry room. There are pipes running above & below. I wish I had known what the finished installation would look like, as I would have changed the placement.
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pochi04
Original Author
15 years ago
Thank you both so much for your feedback!!! How would I go about flushing the unit with vinegar? Would I need a professional to do it?
jakethewonderdog
15 years ago
Thread was just started...

Here is a link that might be useful: flushing thread

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