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WCohn
WCohn, Journeyman Plumber
Category: Plumbing
Satisfied Customers: 874
Experience:  Journeyman Plumber/Estimator
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My gas heater keeps turning off hot water during use. you

Customer Question

my gas heater keeps turning off hot water during use. you have to turn off and back on to get to start working.
Submitted: 10 months ago.
Category: Plumbing
Expert:  WCohn replied 10 months ago.

Hello my name is ***** ***** I look forward to helping you! Can you get me a model and serial number?

Customer: replied 10 months ago.

R75LS serial 08. 05-136958 may 2008

Customer: replied 10 months ago.

mr. wade , you did get my answer? jerry

Expert:  WCohn replied 10 months ago.

I do not see it in my side.

Customer: replied 10 months ago.

model r75ls serial 08. 05-136958 may 2008

Expert:  WCohn replied 10 months ago.

Got it. Rinnai tankless

Expert:  WCohn replied 10 months ago.

Are you getting an error code on the display?

Customer: replied 10 months ago.

I have never mointered the display when IN USE. MY display just indicates temp and up and down arrows. no one ever gave me any info on this heater. I did just this am download troubleshooting manual from rinnai and I may be getting cold water water sandwich due to pressure changes as I live on a hill and had to install a pump and storage tank between my house and the county water supply as the county pressure would not supply all way to house. holding tank will drop pressure causing pump to come on to rebill pressure in tank which is under the house.. your opinion?

Expert:  WCohn replied 10 months ago.

So you haven't actually witnessed it turning off, but you have felt the water go cold?

Customer: replied 10 months ago.

what happens. I will be showering and no problem for a few min then water starts to run cold. I will turn water completely off for about a min and restart and the hot water will come back on. sometimes I have had to do this several times while in shower. more info, just turned on both cold and hot faucets in both baths and went under house to ck heater and it came on for a couple min and then just shut off as if I had turned off the hot water. no error number came up o display

Expert:  WCohn replied 10 months ago.

We need an error code run the hot water like you were showering. The same temp as you normally use and let it run. Don't shut it off until it shows an error code. Some issues require multiple failures before it codes. I'll bet you are getting a 10 or 12

Customer: replied 10 months ago.

I will go turn on shower and go under house and watch heater and get back with in several min. do not go away, tks

Expert:  WCohn replied 10 months ago.

I am a factory trained and certified Rinnai tech. I'm out in the field today so be patient and we will get this figured out

Customer: replied 10 months ago.

heater came on and stayed on about three min then turned off after about a min came back on. was still on when I left but I did notice when it was going off and made a noise like a elec fan speeding up and slowing down but this may be normal . at no time did get an error message number

Customer: replied 10 months ago.

heater turned off that one time and shower has been running for 15 or 20 min and no problem. after reading in manual about cold water sandwich due to water pressure I feel this may have been my problem all along when connected to not having any error messages, possible when my water pump kicks in it keeps enough pressure on heater and does not let water pressure go up and down. your thoughts.

Expert:  WCohn replied 10 months ago.

Okay I'm here to help. Can you send a picture of the control panel?

Expert:  WCohn replied 10 months ago.

Do you still need help?

Customer: replied 10 months ago.

can't send picture but maybe I can describe. top roe, left side- temp gage. right s. - small lite label -In use ... 2ed row LS-up arrow. RS- box labeled (priority). 3rd row- LS- down arrow. RS- on/off switch. at bottom of box (mc81-1us-s)... what did you think about my theory?

Expert:  WCohn replied 10 months ago.

Press and hold UP button and PPOWER button until it display changes. It'll give 01 then an error code 02 and another code. Might go all the way to 09. Write them all down until you get two -- dashes.

Customer: replied 10 months ago.

I just went under house and pressed the up button and (on/off) same time. unit turned off . did not display any error codes , had to press button to get the unit back on. what is this priority button? I press it and nothing happens.

Expert:  WCohn replied 10 months ago.

Can you send me a picture of the vent termination.

Customer: replied 10 months ago.

as explained unable to send picture but vent direct to outside and I checked yesterday when I was running shower the outlet and it was blowing out the vent, no blockage. the heater sets next to the outside wall and vents direct to the outside.

Expert:  WCohn replied 10 months ago.

Well, the problem we have is you are unable to retrieve stored error codes. All Rinnai controllers should be able to retrieve the codes. Can you try turning it off the when you turn it on hold down the on button for three seconds then press the up button.

Customer: replied 10 months ago.

I will try and get back with you. may be tomorrow as I have some other things I have to do. tks

Expert:  WCohn replied 10 months ago.

Okay

Customer: replied 10 months ago.

I did what you advised and the screen went from one to nine and then displayed the two dashes... no one code came up and stayed up. I tried this several times with the same results.

Expert:  WCohn replied 10 months ago.
Ok it should do a 1 --, 2--, 3--, that would mean no codes ever recorded. If you ha had codes it'll be 1 12, 2 10, 3 10, 4 --, that would indicate you have had 3 codes with the most recent being 10.