Their employee Justin killed our gas boiler in two stages, and we were without hot water for 5d and received a bill for 600+EUR.
We were satisfied with this company until now, they even installed this specific gas boiler back in 2021. This year though, they sent a person i had never seen before to do the required yearly "maintenance" (which imho is pretty superfluous, when the positioning of the gas boiler is such that dust ingestion is not a problem).
Justin came, did some things, and left, and afterwards the gas boiler had trouble igniting. The igniter would spark for much longer, and it took much longer to bring the methane-air mixture to ignition, and when it did, it resulted in a small explosion, throwing dust and unburnt methane around the room and even moving the shower-curtain which is 2m away, but at least the boiler then ran properly after ignition.
After a few weeks i had had enough and called them, and the same person had a look at the boiler and theorized that the positioning of the igniter was such that it created a spark to the housing and not near enough to wherever the gas would be released. Sounded plausible, so I left him at it. After a few minutes though he started calling around.
Turns out that now, due to Justin's magical touch, the boiler would ignite but once ignited would go out immediately. His conversations on the phone sounded like he had little plan of what was going on.
When asked, he explained what was happening to me. Now he boiler would ignite properly, but the gas flow was terminated almost immediately once ignited. He stated that either the flame detector or the control unit was damaged, that parts are not immediately available.
So we went from a perfectly working boiler, to one that had trouble igniting but would stay on fine once ignited, to one that ignites and then turns off immediately. All thanks to Justin.
I asked "surely the thermocouple can be measured, as it is just a resistor which changes resistance when exposed to different temperatures", to which i only received a blank look. I did not even get explained that a flamedetector is not a thermocouple, nor did i get explained that this can be measured just fine (which creates a small voltage in the 100-200mV range). He clearly was not well informed about the functioning of these devices (i only have a electronics degree, and never looked into flame detectors before), and was unable to determine which of the two parts could be at fault. So he informed valliant that we needed a vaillant technician and he left.
This was a friday morning, so we were stuck all weekend without a functioning shower. Being who i am, i had read up on flame detectors, and went and measured it and it of course showed it the hundreds of mV required once the methane ignited. Flame detectors things live inside a methane flame and are pretty hard to kill.
The vaillant technician arrived on monday, immediately stated that it was the control unit, which are hard to come by. He said he would rendez-vous the next day with a colleague, who had a controller in his van, and that he would install a new controller in the evening. And so he did, this vaillant employee was one of the most helpful tradespeople i have met in a long time.
So what had Justin done... He either tried to test the assembly with flame detector and igniter outside of the housing, and given the 12kV of the igniter no other path to ground but the flame detector. Or he bent the igniter so far towards the flame detector that the same occurred. One would think that not letting igniter sparks jump anywhere sensitive is an important topic for people who should be certified to work on these boilers. One would also think that if such an error occurs, it is not the customers fault, but the technicians.
Don't ever use this company. Their incompetence will destroy your property, cause a lot of discomfort, waste a lot of your time, and they demand to be paid for it afterwards regardless.
