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Always Something
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Discussion Starter #1
So here is one that had me shaking my head.

Few weeks ago I am at a clients house. A little over a year ago I re-piped the place and installed a 9.31 Noritz tankless heater...relocated everything..yada yada...
So I am back for the annual maintenance and one of the first things I do is check the computer for error codes. I do this mainly to cover my own ass but to also root out any potential issues.

So there is an error code, 760. It's really simple in that the remote communication had/has an abnormality...whatever, I look on the next page and I see a 71.
Humph...never seen that before. So I look it up and it says Gas Valve Drive Circuit Abnormality.

OK, so I start testing the unit by turning it on and measuring the flow versus the temp and at different levels to see the gas valves (all 4 of them) are doing their jobs. I notice no issues at all. I start checking everything..from molex plugs to wiring to voltages at many different points of refference....I find nothing wrong. So I figure, what the hell, I'll call and see what the techs have to say. I get Greg.....nice kid, didn't know too much about things but enough to give me some new info....he started reading all the technicle details from that error code. One of the things he mentioned was a Non-sinusoidal waveform was detected at the control board. I instantly dismissed that as a possibility because things like that rarley happen from the power company (Edison). So he went on and on and we agreed that it was not a big deal and that the unit was working fine after a few more tests. So I proceed to do the flush.

Maybe 30 minutes into it my HO comes home, asks how things are going..blah..blah...I did mention to him about the error code and that I couldn't find anything wrong with it. So a few...10 minutes or so goes by and we are chatting about power outages and such he is asking me about small power generators incase the power goes out for long periods of time....So I told him, I have a honda and it works great. He says ok because the last outage they had was for about 5 hrs and he really wanted to take a shower. So (get this) he tells me he hooked the tankless up to his car's alternator because it puts out 120 volts AC. I stopped him, I said, what did you do...he repeats himself again......For those of you who are electrically inclined this makes sense to you.

For the record, hooking up your 1400 dollar tankless heater up to your Volvo's alternator is not recommended.

But this did explain error code #71 :no:
 

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Illinois Licensed Plumber
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For the record, hooking up your 1400 dollar tankless heater up to your Volvo's alternator is not recommended.

But this did explain error code #71 :no:
Was he an engineer? I always get engineers that like to do stuff like that.
 

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residential service
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1,948 Posts
Tell him to get a 400 watt transformer to plug into the cigarette lighter of the car and then plug his tankless into the transformer. Some vehicles actually have plugs already installed for small appliance use.

Still, very nice that you got the mystery solved.
 

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Always Something
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Discussion Starter #8
Was he an engineer? I always get engineers that like to do stuff like that.

No, he is a camera man...director of photography for major motion pictures and commercials. He is an above average homeowner but knows what not to mess with. Car alternators do not put out a sinusoidal wave form, it is a square wave, Think of when you turn up your bass too loud on your stereo or just have the volume up too high. The wave form changes shape and thus results in distortion. Car alternators do not put out sinusoidal wave forms for various reasons...the charging system...like most systems (digital) is on...off - on...off, versus the gradual on than gradual off. Think of TV flicker when you are watching video of another tv operating...60 hertz...per second.

Originally we were discussing a little 300 watt inverter (DC to AC), but I told him, he needs to buy a high quality unit because the wave form is important, and those cheepie ones can cause issues (just like error code 71) He actually asked me about a jenny, and that is the best solution for suplemental power. Just make sure you plug your appliances into the jenny, and not the jenny into the wall to energize the entire house. This is how utility linemen can get killed. That's my electrical engineering lesson for the day. Ironically when I went to school for this I thought I wanted to do all digital, but found basic analog circuits like this much more interesting...more tangable I guess.

Socked in with fog and everything is washed down this morning so I figured I would do work at home for a little while. Wish the phone was ringing a little more.
 

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Always Something
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Discussion Starter #10
at least he didn't try to do the reverse, try an give his car a jump once the power was back on with a 120v ac circuit:whistling2:
I would pay money to see that. The smell of a burnt coil is like roses to me!!
 

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Always Something
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Discussion Starter #11
and said inverter would have to be an expensive true-sine model. A standard square wave wouldn't run that heater nor a pwm model.
Is there an echo in here?

Very good Protech.....100% correct.:thumbsup:
 

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٩(͡๏̯͡๏)۶&#
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Single phase AC also does wonders for a sealed lead acid battery. Over voltage=off gasing of H2 and O2 gases in a sealed container..........boom!

I would pay money to see that. The smell of a burnt coil is like roses to me!!
 

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Confirm inverter problem

and said inverter would have to be an expensive true-sine model. A standard square wave wouldn't run that heater nor a pwm model.
Yea, I would like to confirm that the car inverter appears to be the problem. My son has a power outage and so he tried to run the Noritz off of his not to expensive truck DC inverter. Same error code 71. The fans etc run, but no flame. I wonder about a computer UPS. Just enough to get one shower.
 

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Yea, I would like to confirm that the car inverter appears to be the problem. My son has a power outage and so he tried to run the Noritz off of his not to expensive truck DC inverter. Same error code 71. The fans etc run, but no flame. I wonder about a computer UPS. Just enough to get one shower.
the problem with most of these control boards is they need a pure sine wave of 60 hz. They are using the 60 Hz as a clock with in the board to control sequencing of ignition (hot surface ignitor) and gas valve .. if hz are not right then gas may come on and try then when that stops ignitor comes on and trys... just the opposite that you require

Even a generator would not give you a pure sign wave....it would work one moment and then not the next.... You would need a large KW generator so that there would be no throttling of the govenor and the gen stays at a constant RPM... any fluctuation in RPM will change the 60 HZ to something lower then to something higher until it evened out
 
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