Faulty 3 way valve tripping electrics? CH only on when HW is

[MirfDiver]

Hi,

I have a fairly old potterton boiler, hot water tank, typical GCH and HW system. Digital thermostat and modern digi timer etc.

Recently its started to trip the electrics at the RCD. With the fused switch to the HW/CH off the electrics are absolutely fine with no tripping. Which is why I suspect the heating system.

When the CH/HW switch is on, (i.e. after I reset the RCD and put fused switch back on) it doesn't trip straight away only when both the HW and CH are on at the same time and even then it can be 30 seconds to 3-4mins later before it trips.

Also the CH doesn't work on its own, it won't start the boiler going regardless of the stat without the HW also being on. So I'm guessing the 2 x things are linked. Bit of internet research suggests it might be the 3 way valve near the HW tank.

Am I on the right track, could a faulty 3 way valve be causing the electric to trip? I've left a few VM's with a few plumbers but thought I would seek some advice on here as well.

Thanks

 

[hertsboilers]

At least you need replace the three port valve, or get it repaired by a new motor. What is its model, Honeywell 4073?

 

[JohnD]

boilers, pumps and motorised valves all contain water, and electricity. A small leak or drip can cause them to meet. This is a common source of RCD trips.

Search hard for signs of leaks.

 

[MirfDiver]

The valve is a 4043h. I've checked everywhere and all wires, pipes and joins etc appear dry, safe and good.

The fact that the CH doesn't come on at all without the HW on at the same time is making me a bit suspicious.

At the moment I'm trying it with just the HW on only with no CH and so far no tripping. Not sure whether that means anything or not.

 

[ianblue]

Sounds like the pump to me that's causing the trip but obviously a check would need to be made to check the insulation.
If your system is what I think it is the Heating cannot run without the hot water if its gravity fed.
This is determined at the programmer.
If you could find the model of the boiler that could be confirmed.

 

[hertsboilers]

4043 is a two port valve and 4073 is a three port valve.

4043 or 4073, two port or three port valve?

 

[JohnD]

if you have gravity HW, then the pump will only come on when the CH comes on, could be that. You could disconnect the pump and see if the fault stops; then disconnect the motorised valve and see if it stops. Park the cores in choc block for safety.

 

[MirfDiver]

Valve is definitely 4043 so I guess 2 port.

I also thought the pump maybe causing the trip. Pump is Potterton Celsia.

Boiler is Potterton Profile 60.

Programmer has 2 x timers for CH and/or HW.

Currently been on HW only for nearly an hour now and no tripping.

Tripping only happens when HW and CH on at same time.

CH only on doesn't fire the boiler at all. CH only warms rads when HW is on as well then within 1 min to 10mins it'll trip the RCD.

 

[hertsboilers]

Just guessing what is your heating system now.

How many two port valves do you have, one or two?

Can you set HW and heating independently on your programmer?

Valve is definitely 4043 so I guess 2 port.

I also thought the pump maybe causing the trip. Pump is Potterton Celsia.

Boiler is Potterton Profile 60.

Programmer has 2 x timers for CH and/or HW.

Currently been on HW only for nearly an hour now and no tripping.

Tripping only happens when HW and CH on at same time.

CH only on doesn't fire the boiler at all. CH only warms rads when HW is on as well then within 1 min to 10mins it'll trip the RCD.

 

[MirfDiver]

Can only see one 2 x port valve in the airing cupboard.

Programmer can set HW and CH independently.

 

[hertsboilers]

This might be your hydro system:

View media item 40062
Either pump or heating channel of the programmer has the problem.

 

[ianblue]

Still not entirely sure whether its gravity or fully pumped system.
If its fully pumped then that would illiminate the pump having the fault.
So if you check if the pump runs when you call for Hot Water only ,then its fully pumped.
The favourite is then the 2 port valve where the motor may be burt out.
The sequence is thermostat calls for heat , sends power to valve , valve opens and when fully open internal switch sends power to pump and boiler.
Must go.

 

[ianblue]

On the asumption that you have a fully pumped system.
Its most likely that the synchrnous motor within the valve has burt out .
This would explain the RCD tripping as the windings in the motor will have over heated causing the insulation to break down and result in earth leakage.
Also the heating would not work properly as the valve would only open partially.
The good news is that the motor can be changed within the actuator and at not a great cost.
You could disconnect the motor within the actuator and see if this solves the RCD tripping out.
Also open the valve with the manual lever , this can be latched in to prevent the valve closing under its spring.

http://www.bes.co.uk/products/112.asp

Good luck

 

[MirfDiver]

Fully pumped system yes.

Today I checked the wiring connections in the programmer. They looked all good but just tightened them up just in case.

Has the CH/HW on together today and both working fine, not had a trip out yet.

CH still does not work on its own though, so thinking the motor in the valve is the most likely cause.

 

[hertsboilers]

On the asumption that you have a fully pumped system.
Its most likely that the synchrnous motor within the valve has burt out .
This would explain the RCD tripping as the windings in the motor will have over heated causing the insulation to break down and result in earth leakage.
Also the heating would not work properly as the valve would only open partially.
The good news is that the motor can be changed within the actuator and at not a great cost.
You could disconnect the motor within the actuator and see if this solves the RCD tripping out.
Also open the valve with the manual lever , this can be latched in to prevent the valve closing under its spring.

http://www.bes.co.uk/products/112.asp

Good luck

Hi ianblue, he said there is only one two port valve of Honeywell 4043, and he can set HW and heating indepandently, how can it be a full pumped system which should have two valves of two ports? Thanks.