Triton [Water temperature cycling hot and cool]what to check

A shower that alternates rather than settling is describing something quite specific, and Triton name it directly: the heater is cycling on the temperature limiter. What that means in practice is a loop. The water reaches the limit, the protection removes power to the elements, the temperature falls, power comes back, the temperature climbs to the limit again, and round it goes at intervals of several seconds. From inside the cubicle it feels like a shower that cannot make up its mind. From the appliance’s point of view it is running continuously against its own ceiling.

Triton’s remedy for this is unusual and it is the most useful thing in the entry: rather than giving separate causes, they send you back to their "water too hot" problem and its three causes — not enough water flowing through the shower, a blockage in the supply, and an increase in ambient water temperature — and tell you to work through those. That is Triton saying, in effect, that a cycling shower is a too-hot shower that keeps being interrupted. The diagnosis is the same and so is the fix.

The reason that framing helps is that it removes the temptation to look at the electronics. A shower cycling on its limiter is not a shower with a control fault; it is a shower being asked to put more heat into the water than the flow can carry away, and the limiter is doing precisely what it exists for. Restore the flow and the cycling stops. Triton add that if it continues after those checks, that is the point at which it becomes theirs rather than yours.

1. 1

   Increase the flow rate using the temperature control, which is Triton’s first remedy. More water through the same heater means the limit is reached less often.

2. 2

   Clean or replace the spray plate in the showerhead. Triton name this specifically, and a scaled head is the commonest reason a shower starts cycling.

3. 3

   Check the stop valves on the supply are fully open, which is the owner’s half of Triton’s remedy for a blockage in the supply. The other half, a blocked inlet filter, is inside the unit behind the cover and Triton reserve cleaning it for installers and service engineers, with a full recommission afterwards, so if the valves are open and the head is clean that is what you book.

   Do not open the unit to reach the filter. Triton’s fault-finding page is headed with the instruction to switch off the electricity at the mains supply and remove the circuit fuse before any fault finding inside the unit.
4. 4

   Select the economy power setting, which Triton give as the remedy for warmer incoming water. Fewer elements means less heat into the same flow.

5. 5

   If it still cycles after all four, Triton’s own instruction is to contact them. At that point it is not a flow problem.