Understand shared temperature settings, priority changes, safety locks and remote-controller wiring.
A continuous-flow heater can have controls in several rooms while still producing water at one selected temperature. A second panel gives another place to operate the heater; it does not create a separate hot-water zone.
These examples concern the Rinnai UK A-Series 11i, 17i and 17e. Control limits and installation details vary between ranges, so use the instructions for the appliance being worked on.
Which panel controls the water?
The panel with priority sets the heater’s temperature. Its priority indicator shows which panel is in charge. Other panels do not average their settings with it or override it by selecting a higher figure. Mixing at an outlet and heat loss along a pipe can still change the temperature a person receives.
Only one panel is assigned as Master. A bathroom must use a Sub controller, with the Master elsewhere. A Sub cannot select above 50 °C. The Master’s permitted settings depend on the appliance configuration and any active temperature lock; do not treat a high displayed setting as suitable for bathing.
Changes while water is running
The controls restrict changes that could surprise someone using an outlet:
- Priority stays with the active panel during draw-off. If the In Use indicator is lit, stop the hot-water demand before moving priority to another panel.
- An increase above 43 °C is blocked during draw-off. Close the hot outlets before selecting a higher permitted temperature. A lower flow that keeps the heater operating does not remove this restriction.
- A high Master setting is not remembered through a return from Sub priority. When the Master was above 50 °C, transferring priority to a Sub and back leaves it at 50 °C. This is an intended safety action.
Demonstrate these behaviours at handover. A panel refusing one of these changes is usually doing its job, not failing. Check the actual water temperature before use, especially after someone changes a setting.
LOC on the display
When the selected temperature alternates with LOC, the controller-lock function is active. It locks the connected panels together. This is different from an appliance fault code; it does not mean a gas-supply, fan or overheat fault. Follow the controller instructions to manage the lock.
Wiring and positioning
The heater supplies its wired panels with 12 V DC. Keep mains voltage off the controller terminals and isolate the appliance’s electrical supply before making connections.
Additional controllers connect in parallel using the specified connection arrangement. Series wiring can disrupt operation and damage components. The communication connection is not polarity-sensitive: either of its two wires can go to either controller terminal.
Route the communication cable away from household mains wiring. Nearby mains cables can introduce interference; investigate routing and the manufacturer’s shielding provision if communication is unreliable. Reversing the two controller wires does not correct interference.
Choose a clean, shaded position away from heat, steam and direct spray. Water resistance does not make a panel suitable for a shower jet. The manual places it at least 40 cm above the highest part of a sink, basin or bath, alongside its other positioning requirements.