2Year old house w/Rinnai R85 gas tankless water heater never flushed (never knew).
125Ft well - cold pressure super.. no whole house filter - only in-well sediment screen.
(Wait for it) recent onset low hot water pressure throughout. Open more than one tap at a time? Trickle Down!
White buildup on Moen showerhead - tried CLR & no joy. Had to start somewhere.
Cleaned all tap aerators and saw what looked like tiny bits of soft tan sawdust. No recent water line breach.
Tank splutters/gurgles when hot tap first opens - sounds like inlet is restricted?

Is this a tank flush situation? I see directions for flushing on this website and wonder how to tell which line to open. I have INLET and OUTLET pipes and each has a threaded access cap with upstream valve lever. I'm quite willing to have a go at flushing but need to convince hubby that we can really do it ourselves (He's ex. RAF Fitter) HMMM!

Close lower Red and Blue valves. Handles should be in horizontal position.

Remove caps with chain attached to them. Install Flush Kit to each side. Open Upper Red and Blue valve. Activate Flush Pump system with cleaning solution
. Follow instruction as per manufacturer.

When finished, follow the same instructions but in reverse.

Since you are on well, you probably have high mineral content in your water. Have test done on your water to determine what kind of water conditioning system you should install to prevent same problem in the future.

Milo, thank you. I checked the Rinnai Recommended Flush Procedure. The one listed is for Scale buildup and has one hose attached to the circulating pump + the 2 you listed and includes a pail of Vinegar in the loop. There is no pump attachment on mine. Can I ignore this part of the procedure for a straight flush? Also, I have learned how to remove/clean the filter. Wow! Hot water again.

Would you please tell me how to remove & clean the filter.

Thank You, drs4400