TKjr.

[Keyser]

Good. orning. I have a 2004 TKjr. on demand unit, it wasn't producing hot water. The LED was solid red. Powered the unit off and on, to reset. It is currently working. This is getting more frequent.
I am currently on my 3rd circut board. the previous ones show burn marks (the clear sub stance the board is coated in is brown). Never found out why the board was burning out.
I flush the system quarterly, and clean the filter monthly. I just cleaned the filter 2 weeks ago.
Any suggestions?

 

[Breplum]

Start putting aside $ for an upgrade to a new, modern unit.
I remember the special event dinner Takagi put on when they unveiled that model. Then the next day they gave a tear down training. After tearing down and re-assembling one, I swore it was beautiful and stupid at once.
Modern condensing and non- condensing tankless from Navien (with a two line smart digital display) and Noritz and others are so much smarter, better designed with completely easily replaceable, quick-clip parts. The idea of a tear down to fix is obsolete. Sorry I can't recommend throwing any effort further.