CH Tripping Electric - Faulty 3-Port Valve?

[keithmdw]

A couple of weeks ago we had the CH on to dry some clothes and the electricity in the house tripped. Didn't think anything of it and put it back on. No problems.

Today it was raining, and I needed to dry some stuff I didn't want to put though the tumble dryer, so I put the heating on again.

Again, the electricity tripped. This time I did some investigation, and found the following:

DHW on and no problems at all - everything fine.

CH on and 3-port valve starts making a funny crackling kind of noise and about 10 seconds later the electricity trips out. I can replicate this every time so it's definately this I think which is at fault.

The 3-port valve was replaced about 8 months ago when it failed to open properly for the CH to work.

With it now apparently tripping the electricity on CH but not DHW, would you say the valve is broken? I guess the noise coming from it suggests it is broken.

Could it be anything else? Could something else have caused it?

 

[simond]

Did it trip an RCD or an MCB?

Do you run your HW off an immersion in the summer or have you been using the boiler daily for HW?

It is unusual (but not impossible) for a 3 port to have an earth fault. Is it a metal cased 3 port or a double insulated plastic one?

 

[gas4you]

At 8 months old it should still be under warranty. Get the engineer who fitted it back to replace it.

 

[keithmdw]

RCD/MCB? It tripped the switch in the fuse box which turned ALL the sockets in the house off but left the lights working.

We have been using DHW pretty much every day for hot water, but not using the CH since it warmed up. I have the DHW on now in fact and all is well.

 

[gas4you]

Sounds like the RCD then, = imbalance between live and neutral so something leaking to earth.

 

[simond]

Yes, you have an earth leak. I suspect the insulation of the stepper motor is breaking down. All the components after the valve are shared so you are probably correct in your diagnosis.

However, there is no substitute for testing and one is assumng that your installation is standard. We see all sorts of lash ups that aren't, so there is a limit to diagnosing faults over the net.

If you have no redress with the installer from 8 months back, you will probably find changing the valve head (just the electric bit) within the scope of your skills. Should cost around £50.

 

[keithmdw]

Thanks everyone. I will call on Monday and try and get it sorted before the cold weather starts creeping in again - they had to special order the valve last time

 

[gas4you]

What make of valve is it then?

 

[keithmdw]

Potterton

 

[gas4you]

Can't understand why this was a special order then, they are easily available and I usually carry them on my van

 

[keithmdw]

Plumber had to order he said and it took about 3 weeks to get it in if I remember correctly. Maybe it was just his supplier?

 

[gas4you]

I would have thought this was a potterton/myson power extra valve. Next day delivery from Plumb Center

 

[simond]

Yes, that would explain why it got stuck.

If you want the next one to last more than 8 months, suggest you rip it out valve body and all and buy a Honeywell. My experience of the Powerextra is that the slightest bit of grit or crud and it seizes up.....

 

[Dan Robinson]

Well it is Electrical and a Potterton!!!

 

[keithmdw]

The whole system is Potterton and has had more problems that I can mention.