I have a customer with a problem of RCD tripping caused by the wet UFH systems.
There are 5 UFH areas each with a Wilo Para pump attached. Along with this there are 5 Grundfos pumps assisting the flow of water around the property.
The System is setup with Heatmiser NeoStats wired through the Heatmiser UH8 & UH4 wiring centres.
The Ground floor UFH system has a boiler demand cable that signals a 2 port valve and a Grundfos pump to operate. The 2 port then signals the boiler to fire.
The 1st & 2nd floor UFH systems boiler demands are connected and signal a 2 port valve and Grundfos pump.
There are 2 smaller systems in the Annex that are connected, operating another 2 port and Grundfos pump.
Along with this there is a towel rail circuit with a 2 port and a Grundfos pump controlled by a Heatmiser Neostat Timer and a hot water circuit also with a 2 port and Grundfos pump.
The system has been working for about 3 months without any problems until the customer finally moved in. Approximately 2 weeks after moving in the RCD controlling the central heating has started to trip. If I turn off the 1st & 2nd floor UFH everything operates fine. If I turn off the ground floor and then turn on the 1st & 2nd floor everything works fine.
The first thing I checked was picture hanging over the stat positions, no cabling has been damaged.
The RCD in the CU is a 100A 30mA and has the boiler, 2 x UFH, Hob, Microwave, Oven, Immersion with secondary pump, Annex lounge sockets.
I have checked the insulation resistance of all the other circuits and they are all over 300M ohms so nothing that can affect the RCD.
Turning on the UFH, the wiring centres go through a start up process then send power to the Neostats. They in turn go through a start up process and then turn on sending a signal back to the wiring centre to turn the boiler on. It's at this point that the RCD trips.
I have unplugged the pumps on the UFH manifolds and the system doesn't trip when the Neostats send the signal back.
I am thinking that the pumps are faulty, but when checked independently I can find no actual fault.
My question is why when one system is switched off the system operates OK and then when the power to the systems are switched around the system works OK but with all the systems on it trips the RCD?
RCD ramp test indicates that it's tripping around 19mA.
1/2 test indicates no problems.
Any help appreciated.
There are 5 UFH areas each with a Wilo Para pump attached. Along with this there are 5 Grundfos pumps assisting the flow of water around the property.
The System is setup with Heatmiser NeoStats wired through the Heatmiser UH8 & UH4 wiring centres.
The Ground floor UFH system has a boiler demand cable that signals a 2 port valve and a Grundfos pump to operate. The 2 port then signals the boiler to fire.
The 1st & 2nd floor UFH systems boiler demands are connected and signal a 2 port valve and Grundfos pump.
There are 2 smaller systems in the Annex that are connected, operating another 2 port and Grundfos pump.
Along with this there is a towel rail circuit with a 2 port and a Grundfos pump controlled by a Heatmiser Neostat Timer and a hot water circuit also with a 2 port and Grundfos pump.
The system has been working for about 3 months without any problems until the customer finally moved in. Approximately 2 weeks after moving in the RCD controlling the central heating has started to trip. If I turn off the 1st & 2nd floor UFH everything operates fine. If I turn off the ground floor and then turn on the 1st & 2nd floor everything works fine.
The first thing I checked was picture hanging over the stat positions, no cabling has been damaged.
The RCD in the CU is a 100A 30mA and has the boiler, 2 x UFH, Hob, Microwave, Oven, Immersion with secondary pump, Annex lounge sockets.
I have checked the insulation resistance of all the other circuits and they are all over 300M ohms so nothing that can affect the RCD.
Turning on the UFH, the wiring centres go through a start up process then send power to the Neostats. They in turn go through a start up process and then turn on sending a signal back to the wiring centre to turn the boiler on. It's at this point that the RCD trips.
I have unplugged the pumps on the UFH manifolds and the system doesn't trip when the Neostats send the signal back.
I am thinking that the pumps are faulty, but when checked independently I can find no actual fault.
My question is why when one system is switched off the system operates OK and then when the power to the systems are switched around the system works OK but with all the systems on it trips the RCD?
RCD ramp test indicates that it's tripping around 19mA.
1/2 test indicates no problems.
Any help appreciated.