About 6 months ago was asked to look at a fault heating (oil burner) not working and also no hot water. A quick flick with my over sensitive voltage stick showed supply was present at the controller the supply was was present but controller inoperative no indicator lights nothing. Not like the old days where a dry joint or burnt out resistor was detectable ,now sealed electronics so I had to get another one ,this fixed the problem. However this week got a call heating off again and no hot water. This time there was no supply at the controller or thermostat , the fault was the supply a 40 AMP 30mA DOUBLE POLE RCD 230V ZR40 BS EN 61008. Whoever installed a new boiler about three years ago correctly used a small 2way consumer unit RCD with a 6amp MCB along side it , one MCB spare. The RCD toggle had no switching action (not latch)even a bit of thumping no good. Now why would a RCD sitting in a consumer unit for three years never been touched switch mechanism go faulty. Even when taken out and replaced I could not get the removed one it to latch. Something is common to these two separate faults. Thinking along the lines could switching on a boiler oil burner unit at the same time as the circulating pump and other hot tank controls cause a damaging spike , its very odd. Don't know if the RCD has a electronic latch or mechanical latch , but I will go back and get it if not dumped and cut the dammed thing open to look.
Any Voltage spike would be created when any inductive loads are disconnected surely? Or are you thinking of initial inrush currents? I am currently trying to educate myself on the inner deeper, darker parts, of oil fired boilers. The last one that I looked at had a 5 Amp fuse it its fused connection unit, rather that the 3 Amp size I usually find in gas boiler fused connection units. I believe that oil fired boilers may have an H.T. transformer to create a spark for fuel ignition. We don't normally have any problems with central heating circulating pumps do we, regarding spikes.
Any Voltage spike would be created when any inductive loads are disconnected surely? Or are you thinking of initial inrush currents? I am currently trying to educate myself on the inner deeper, darker parts, of oil fired boilers. The last one that I looked at had a 5 Amp fuse it its fused connection unit, rather that the 3 Amp size I usually find in gas boiler fused connection units. I believe that oil fired boilers may have an H.T. transformer to create a spark for fuel ignition. We don't normally have any problems with central heating circulating pumps do we, regarding spikes.
