RCD tripping - - - Bad Drayton mid position valve - - - Help desperately needed !!!

[skywatch]

Hi,

Breifly I woke up last week to the sockets not working in the house, reset the rcd and all was fine......for 2 days.

Then it happened again. This time I traced a burning smell to the airing cupboard. It was coming from the 3 port mid position valve (a drayton 670H340-30L0).

Inside the valve resistor R1 was charred but showing 2K7 on a meter, is this correct? (Drayton refuse to tell me the value of this component - awful customer service). It seems that the neutral connection to the valve had never been screwed down and was loose. R2 on the board is OK at 67K.

The valve works and so does the HW and CH, but the RCD still trips occasionally and today would not reset until the boiler power had been removed. Restoring boiler power does not cause an RCD trip!

The synchron motor measures 2K6 across it's windings and infinity from the windings to the case, so not likley to have earth leakage current there.

Can anyone help me with this please?

Andrew

 

[AWheating]

Re: RCD tripping - - - Bad Drayton mid position valve - - - Help desperately needed !

an rcd trips on earth faults not over current, so it sounds like there is a faulty to earth somewhere. doing some insulation resistance tests on the heating circuit cables would iliminate a cable fault if you dont think its the zone valve.

 

[Whn1]

Re: RCD tripping - - - Bad Drayton mid position valve - - - Help desperately needed !

I thought they tripped on live/neutral faults.

 

[kimbo]

Re: RCD tripping - - - Bad Drayton mid position valve - - - Help desperately needed !

A common problem with heating systems tripping rcd,s out is as AWheating says it is usually the Central Heating pump. Disconnect the live to the pump and turn on to test.

 

[AWheating]

Re: RCD tripping - - - Bad Drayton mid position valve - - - Help desperately needed !

they trip when there is an inbalance in the magnetic field between the live and neutral, this is caused when either the live or neutral shorts to earth.

fuses and circuit breakers on the other hand are over current protection to protect the circuit cables mainly.

 

[Whn1]

Re: RCD tripping - - - Bad Drayton mid position valve - - - Help desperately needed !

Is there any chance the motorised valve could have gotten wet?

 

[Millsy 82]

Re: RCD tripping - - - Bad Drayton mid position valve - - - Help desperately needed !

A common problem with heating systems tripping rcd,s out is as AWheating says it is usually the Central Heating pump. Disconnect the live to the pump and turn on to test.

Or gas valve, Fan, 3 port valve, PCB pretty much anything with 240v going to it. Even had a cyl stat tripping rcd today

 

[skywatch]

Re: RCD tripping - - - Bad Drayton mid position valve - - - Help desperately needed !

WOW!!

Thanks for all the fast responses, it's really appreciated guys!

Anyhow, I have disconnected the electrical supply to the valve and left it locked in mid position. If it still trips then it's not the valve, if it does then I need to look into the pump by disconnecting the pump from the distro and putting an rcd between the pump and the distro. That should trip if the pump is at fault, no?

Anyway, back to some of my original questions.....

1. Anyone know the value of R1 on the midposition valve?
2. What situation would cause this R1 to get hot and charred?
3. Would the loose neutral cause the above fault?

Thanks guys. I bought this as a new house and this is the third neutral I have found that was not screwed down!

Cheers

Andrew

 

[AWheating]

Re: RCD tripping - - - Bad Drayton mid position valve - - - Help desperately needed !

any loose connection can cause a high resistance point which will create a build up of heat.

The national electricity grid fly helicoptors around there pylon's and using infra red camera's looking for heat spots. Any part of the cable's and there connections that show alot of heat indicates to them that the joint is possibly becoming loose creating a higher than normal resistance.

a useless fact i know but explains it well.

 

[skywatch]

Re: RCD tripping - - - Bad Drayton mid position valve - - - Help desperately needed !

UPDATE ...........

With the valve disconnected no trips for 35 hours so looking hopeful.

Trouble is NO CH!!! - Now, will it work if I put a link from live to where the orange wire from the valve connects in the airing cupboard distribution board? Currently I only get heat when there is a call for HW with the valve manually locked in the MP.

Thanks

Andrew
PS The police 'borrow' those helicopters as well to look for canabis factories.

 

[cr0ft]

Re: RCD tripping - - - Bad Drayton mid position valve - - - Help desperately needed !

I thought they tripped on live/neutral faults.

Only earth faults. They will trip if there is a borrowed neutral on the circuit though, maybe that's what you are thinking of.

 

[Unregistered]

Re: RCD tripping - - - Bad Drayton mid position valve - - - Help desperately needed !

This was my problem. Away for a week with everything turned off. On arrival home switched on central heating and instantly tripped rcd. Disconnected power supply to pump, no tripping of rcd. Couple of taps with with hammer to body of pump, reconnect power supply to pump, all working fine. Incidentally, pump less than a year old but we do live in hard water area. Hope this helps someone.

 

[Timerman]

Re: RCD tripping - - - Bad Drayton mid position valve - - - Help desperately needed !

Only earth faults. They will trip if there is a borrowed neutral on the circuit though, maybe that's what you are thinking of.

Could this be my problem?

I live in Bulgaria and just had a central heating system installed so all of it is brand new parts, when it came to using the system for the first time the pump tripped the RCB

Over here they don't have Earth as such, it's normally a link in place between Neutral and Earth to return it to the power house in the street to be earthed.

The Pump is running for a max of 10 minutes before the RCB trips

 

[Dotty]

Re: RCD tripping - - - Bad Drayton mid position valve - - - Help desperately needed !

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