Worcester 15Ri always on.

[BeeBhoy88]

Hi All, new to commenting on this forum but have always been impressed with the quality of advice so here goes. Have been called out to a boiler always on among other faults. Replaced 3PV, which was faulty, and completed other task. However, boiler still on, receiving power from 3PV even though room and cyl stats turned off and programmer set to off.

The customer had lots of work done in the past so I rewired wiring centre and had the same problem. The LR connection at the boiler was receiving power and I traced it to the 3PV. It was sending a 70v signal to the boiler when dormant. It did send the correct 240v when meant to but the 70v is enough to keep it going.

I swapped out the 3PV and still had same problem. Are there any 3PV's which have a 0v when idle? Any other ideas? Customer has to turn off dial at boiler when not required. I've asked around and no-one can shed any light on it or suggest anything that I haven't tried. Look forward to the responses. Thanks.

 

[jackthom]

Some boilers do seem to be over sensitive to the 'leakage' voltages on the orange wire of 3 port valves.

In other threads there have been suggestions that a capacitor from orange to neutral can considerably attenuate this voltage and keep the boiler from firing permanently.

This one should do the job...

http://www.maplin.co.uk/p/lcr-metallised-polypropylene-500v-01uf-capacitor-rg23a

 

[BeeBhoy88]

HI jackthom, thank you for your prompt response. I had an electrician mention about a capacitor when in a builders merchants whilst talking to a plumber friend but I'm afraid to say that I discounted his advice. I will give that a go and report back.

I have checked the link and I'm no electrician and would like to clarify where exactly the capicitor would go. Do I simply link one end into the orange wire (with LR wire to the boilerand cyl stat) and the other end into the neutral?

 

[jackthom]

Yes it will go in the wiring centre with one end connected to the main neutral terminal (Blue, usually #2 from the left if wired as in the sundial Y-plan diagram) and the other end goes to the terminal where the 3 port valve Orange is connected, ie the boiler Switched Live.

It doesn't matter which way round the capacitor is connected and it would be a good idea to fit some insulating sleeve over the exposed wire ends for safety.

Someone recently said the stray voltage on Orange had dropped from initially around 100V to less than 20V with the capacitor fitted so it should work.

 

[cross thread]

have you checked boiler is not in a service mode ?

 

[BeeBhoy88]

Hi Gordongas, yeah, I checked that it was in normal mode and not 'Max' or 'Min'. I was hoping it was that and have an easy fix but it wasn't to be. There is definately voltage leakage from the orange that is turning on the boiler. I spoke with Worcester technical but they didn't shed any light on it. I think the capacitor is the next thing to try. I've booked it in for tomorrow pm.

 

[BeeBhoy88]

Hi Jackthom, just a quick update. I fitted the capacitor as suggested and it looks good from the get go. I've asked her to keep an eye on it for a few days before we settle up. So far so good. Thanks for the advice.