Rinnai RXP no/low flow displayed

candagrm2

Recently installed a new RXP199iN unit. If only one faucet is open the unit will register 0-0.2gpm of flow and not turn on even though normal flow is observed at the faucet. If multiple faucets are opened, or the PRV is momentarily opened, it will register expected flow even from only one open faucet (~1.4gpm) and the unit will kick on and operate normally. The unit will operate normally like this until it sits for several hours and will again not register flow until either several faucets are opened or the PRV is hit momentarily.

The flow turbine was removed and checked for obstruction but nothing was found. It spun normally.

pedmec

Check the gpm rating of the aerators. or just remove it. might be below the minimum flow rating for ignition. Most on demands will not turn on unless a minimum of 0.5 gpm is flowing. Some can be adjusted in the settings for a lower flow but you will have to read the manual

candagrm2

Update: This looks to be remedied by turning off recirc and disconnecting the thermal bypass valve. I'm still curious why this would be the case and how to properly remedy it so that recirc can be used.

Larry Weingarten

Hi, Does the recirc have a check valve in it that you know allows no backflow through it? 🤔
Yours, Larry