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.

 

[Leesparkykent]

Well whatever it is, the fault is more probably within the boiler, associated wiring, values etc. Before continuing I would contact Valiant, before proceeding further IMO.

Why would you bother contacting valiant? its not like they are going to see a fault over the phone. The boiler has L N E and a switch live to kick the boiler in when required. The boiler fires on heating but trips on hot water when turned on at the programmer. If you think about it logically it cant be a fault with the boiler as the switch live is used for both heating and hot water and its fine on heating.

 

[Pauldicker]

Well whatever it is, the fault is more probably within the boiler, associated wiring, values etc. Before continuing I would contact Valiant, before proceeding further IMO.

Thanks. The customer is going to get a new controller and if that does not work i have told them to get another heating engineer not the guythat installed it or serviced it yesterday(same guy) as he is blaming me somehow.

 

[Pauldicker]

Why would you bother contacting valiant? its not like they are going to see a fault over the phone. The boiler has L N E and a switch live to kick the boiler in when required. The boiler fires on heating but trips on hot water when turned on at the programmer. If you think about it logically it cant be a fault with the boiler as the switch live is used for both heating and hot water and its fine on heating.

Yes if you have one on heating it works but if you then turn on the hot water to run at the same time it trips..

 

[Leesparkykent]

Ita like talking a different language to me

You need to get some one in that does know then. Its not difficult its a set of switches in series.

 

[Leesparkykent]

Yes if you have one on heating it works but if you then turn on the hot water to run at the same time it trips..

what if heating is off and you just turn hot water on by itself?

 

[Pauldicker]

Its a system boiler so more than likely an unvented set up. If its unvented there will be 2 x 2 port valves or a 3 port with a two port for interlock on the cylinder.

This is what was connected. Just wrapped in duct tape

 

[Pauldicker]

what if heating is off and you just turn hot water on by itself?

Didnt seem to come on but was not sure if it was because water was still hot

 

[Midwest]

Why would you bother contacting valiant? its not like they are going to see a fault over the phone.

Wasn't suggesting they fault find, just making sure there are no devices/circuits within Boiler susptible to a 250v IR test, or would skew such test, even L/N to earth.

 

[Leesparkykent]

Didnt seem to come on but was not sure if it was because water was still hot

turn the cylinder stat up then so it does come on.

 

[Leesparkykent]

This is what was connected. Just wrapped in duct tape

View attachment 33930

The one with duct tape is still connected to the black of the flex as cant make out from the pic?

 

[Pauldicker]

turn the cylinder stat up then so it does come on.

Tried that. But nothing but the customer dod say that last week it blew a 3amp fuse so he replaced it with a 5amp and got the guy to service it and then it worked. Im thinking something was wrong before i even got there

 

[Pauldicker]

The one with duct tape is still connected to the black of the flex as cant make out from the pic?

It has an s on it so i assume its the switch live.

 

[Pauldicker]

It has an s on it so i assume its the switch live.

It is the cable with the live in a connector block not attached to anything.

 

[Midwest]

Why would you bother contacting valiant? its not like they are going to see a fault over the phone. The boiler has L N E and a switch live to kick the boiler in when required. The boiler fires on heating but trips on hot water when turned on at the programmer. If you think about it logically it cant be a fault with the boiler as the switch live is used for both heating and hot water and its fine on heating.

Can't see how that works, as it appears to have an internal diverter value.

 

[Leesparkykent]

It has an s on it so i assume its the switch live.

more than likely as the boiler needs l n e and sl. With out knowing what plan it is etc its just guess work. But I would bet changing the programmer is going to achieve sweet FA.