PULSACOIL 2000 NO HOT WATER LED PSC LIGHT CONTINUOUS FLASHING

Hi
started with no green light/fault light on. had system checked & told immersion heaters needed changing.
drained & refilled system & exchanged both immersion heaters & reset overheat button.
green light back on ok / no fault light on.
still no hot water on off peak or peak selection.
checked PSC LED light pattern - this shows as normal operation on occassion then changes to continuous flashing then settles down
again, then flashes continuous again. this carries on like this.
could you confirm what the problem may be with continuos flashing of the PSC LED light then back to normal operation??

Many thanks
mj.

Further update
stored water whilst on off peak is now hot, hot outlet copper pipe into top of heat exchanger is now also hot. copper pipe
coming out of top of heat exchanger (hot outlet dist pipe ) is cold & no hot water from hot taps.
Could this be the work of a faulty DHW temperature sensor???
Thanks

Hi mj,

Yes this is DHW sensor failure.

With new heater elements you should also have new thermostats with integral overheat protection. The installer could have therefore bridged out and removed to old overheat thermostat.

Cheers, Mike