pulsacoil III dhw problem

hi all please could someone offer me some advice on a pulsacoil problem, i ahve been asked to look at one of these as the hot water supply is at best sporadic. when i got there i was informed that someone had looked at it before and had removed some parts to make it work . on inspection i cannot find any parts that have been removed the , header tank was below the float switch so topped that up which broought the green neon on for water level .the other green neon refuses to light , although i suspect the neon rather than overheat, on inspection of the wiring i have found a wire has been added going from connection 1 on main terminal block which is live feed in it goes up and is connected to the right hand terminal on the reset button, this looks like some sort of bypass but the question is why would someone jump it there, i have replaced both thermostats with new ones preset at 60 degrees so can i assume i can remove the old reset switch and overtemp thermocouple now.
the next quetion is can i turn both stats to 70 degrees which is the max on them , also even after changing thermostats water is still not very hot for very long,will this be a fault with the dhw sensor or the flow switch it sort of runs warm then cold then hot then back to cold all in space of 40 seconds to a minute also there are 3 supplys.to the boiler one is marked pump one is marked booster and the other is unmarked .

to test the sensors can i bridge the pcb to see if system works if needs be with a variable resistor, the reason for doing this would be purely elimination before buying parts .

also is it normal for the relay to buzz away quietly, know this is a lot top ask but any help appreciated thank you

the board led is flashing about once every 2 seconds , and looking at the bypass wiring looks like it powers up the coil on the relay if so removing and bridging the overheat sensor and switch would have the same effect

Hi,

If parts have been removed or bypassed, I would highly recommend you call out an expert to review the system completely.

It will be the sensors. very unlikely to be board unless it has been damaged whilst shorting out!

I stand behind what I have said.

If components have been bypassed, call someone out who knows the system to establish what is wrong and if anything is unsafe. I have been to a few job where the installation has become unsafe due to people messing around guess what is wrong.

Dont bridge / short anything out. It is normal for the relays on the board to buzz. This is the relay for the pump. If you can hear it fluctuating I.e the buzzing getting louder then quieter rapidly I.e roughly 5 - 15 secs and your hot water is doing the same then its the sensors.

In the most likely scenario it would be the sensors.