beginner plummer. New home with Lochinvar Noble temperature fluctuations and OUTLET MRHL error

hey guys so i recently moved to a new home and was trying to trouble shoot an issue with our tankless water heater. The mode lis Lochinvar Noble. I tried to solve this problem before I tried to hire a professional to deal with it. I would like to understand the basics at least so I don't get ripped off.

The problem I have occurs since I moved in. The shower temperatures would fluctuate hot and cold during usage. Faucet seems okay and doesn't seem to have the same issue. Recently there was errors from the unit which are OUTLET ARHL and MRHL. I resetted it and it seems to do the same thing. I did the full reset with the easy setup with factory recommended settings and it didn't seemed to help.

I was told to check a few things, which includes to purge the air inside the system, and to check if i'm losing pressure on the valve. However I would like to make sure if there are settings are correct before continuing.

I've searched everywhere on the internet and haven't found an answer at all but if I can get any help then that would be amazing.


  • edited June 13
    Hi! I think you should contact a specialist in this matter and call him to your home. It is the only way you will surely be able to fix the problem and solve it. I do not understand such details. Therefore, when I bought a house, I warned my Mortgage Advisor Doncaster that I needed all water supply, heating systems, electricity, and the Internet to work perfectly. There would be no need for repairs. I am very happy with what I got, including thanks to my mortgage adviser.
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