Rcd tripping issue.

[Pauldicker]

Can someone shed some light on a problem I'm having.
I changed a CU today as there were only 6 circuits they are all now rcbo's there was no rcd protection prior to that.
On the ground floor circuit the rcd test was x1@ 147ms and x5@ 23ms.
However now when the customer turns the heating on its fine and if they turn the hot water on at the same time it's tripping the rcd.
It is run from a fused connection unit and upon looking all looks good in the fcu.
It's a valiant ecotecplus 618 and the controller is a lifestyle lp522
I'm not a heating engineer but I may be missing something obvious.

 

[Andyrc]

Uuumm? Sounds like the heating element may be faulty. And why WOULDN'T you isolate any electronics etc BEFORE doing any IR tests. No accounting for experience / knowledge .

 

[robmiller69]

Hi, I had a fault phoned in. They'd had other electricians go there who changed the 30m/a Rcd to a 100m/a rcd.
I advised it needed to be a 30m/a but there was no fault but upon further investigation once the boiler had fired up it would trip out after 1-2 min. I ended up testing it right after and you'd see the fault slowly disappear over 45 seconds.
Give it a try. You may be surprised.
You didn't mention if any other rcbos where tripping. If so there's a crossover.

 

[David M]

It only trips if you ask for heating and hot water at the same time.

Which is why Lee asked you if the system has one 3port valve or two 2 port valves. Also if the problem occurs when calling for just water. If it's a 2 valve system and the fault occurs when calling for HW in both instances then first port of call would be to check the motorised valve. They are generally easy enough to check and simple to swap the solinoid

 

[sedgy34]

Can someone shed some light on a problem I'm having.
I changed a CU today as there were only 6 circuits they are all now rcbo's there was no rcd protection prior to that.
On the ground floor circuit the rcd test was x1@ 147ms and x5@ 23ms.
However now when the customer turns the heating on its fine and if they turn the hot water on at the same time it's tripping the rcd.
It is run from a fused connection unit and upon looking all looks good in the fcu.
It's a valiant ecotecplus 618 and the controller is a lifestyle lp522
I'm not a heating engineer but I may be missing something obvious.

Is this heating system a Y plan by any chance a 3 port valve tripping when switching over ?

 

[David M]

Is this heating system a Y plan by any chance a 3 port valve tripping when switching over ?

I don't think the o.p is sure he's not familiar with heating systems. He was asked if the problem occurred if calling for HW only. But it is uncertain whether or not that was the case. If the controller was wired incorrectly (based on him stating that the system operated the opposite way round) really it would be best if someone more experienced in heating systems take a look. I suspect it is a relatively easy fault to find and fix if the person knows what to look for.
The trip fault will almost certainly be external to the boiler and most likely be only one of two things provided the system is wired up correctly.

 

[freddo]

I wanna do it! I love fault finding heating systems! Hanging connector blocks and duct tape can't be good, wether it's working or not. It's shocking the number of heating systems I've come across (usually y plan) that don't work correctly, and the user has just accepted that it doesn't work as it should.

 

[Leesparkykent]

I wanna do it! I love fault finding heating systems! Hanging connector blocks and duct tape can't be good, wether it's working or not. It's shocking the number of heating systems I've come across (usually y plan) that don't work correctly, and the user has just accepted that it doesn't work as it should.

That's normally because the plumbers had a go at it lol.