Boiler- could this be possible?

[brizospark]

Called to a boiler fault today where the heating was not working - tenant just moved into house.
So I had a look and realised tat someone (probably the heating engineer who was there before me) had been altering the wiring. They had swapped connections about in the time click and room stat in the hope they would fix the problem

So I belled all the cables out and reconnected correctly through the time click and room stat, powered up and heating kicked on. Seemed to be good but when trying to switch the heating off it was staying on.

Double checked my wiring, all ok, but I was getting 230v back from the boiler to the switch wire of the room stat. I opened up the control panel of the boiler and noticed that the voltage was coming from the volt free contacts which read 'do not put voltage onto these terminals as this will result in severe damage to boiler'

I had wired the controls correctly, volt free, but is it possible that whoever was tampering with the wiring has put voltage onto these contacts and damaged the circuit boards, resulting in voltage back feeding from boiler to these terminals?

 

[Stuuk1]

Perhaps I'm being naive, but what's the point of a volt free relay terminals if you can't connect a voltage to them?

Are they purely for test purposes?

 

[Des 56]

It is just a switch,as in volt free,the power source is the bolier itself

 

[Des 56]

Does the boiler fire with the volt free terminals not connected and does it fire with just a link between them
What are you reading when it is linked out

 

[Megavolt]

If you put 230 to the volt free side it fries the pcb seen it before.

 

[brizospark]

Even with nothing connected controls wise and just power to the boiler there is still 230v across the common and normally open volt free terminals, thus firing the boiler

 

[Sintra]

Those could be the stat terminals at the boiler. What make / model is it?

 

[Des 56]

Even with nothing connected controls wise and just power to the boiler there is still 230v across the common and normally open volt free terminals, thus firing the boiler

My understanding,the volt free terminals need to be linked either internally or through the external stat for the boiler to fire

Are you sure these terminals are definitely volt free and not 230 rated
I would have thought the pcb would be cooked but I can't see, even then, how you would get 230 on these outputs

 

[Guitarist]

Nothing to do with the frost/pipe stats?

 

[brizospark]

Under the terminal block it states volt free contacts do not energise I think the pub has melted and is transferring 230v to these terminals , something else in the Pcb must be fried making the boiler think that there is a demand for heating

 

[brucyboy]

Is there a motorised valve? Could still have the live link in at the wiring center or wrong type of motorised vale for volt free switching.

 

[brizospark]

How far into boilers are sparks allowed to divulge before going into gas safe territory?

 

[Geordie Spark]

How far into boilers are sparks allowed to divulge before going into gas safe territory?

I don't know how things stand today, but I always considered it ok for a spark to play with the sparky bits, but not the gassy bits, so don't take the cover off the combustion chamber, don't mess with the flue and definitely avoid the gas valve and associated gas pipework.

No doubt there'll be some new reg. somewhere that shoots me down in flames .............. :83:

Oh happy days.

 

[PEG]

I would be in agreement with the sparky/gassy seperation. Inspecting and even accidental touching is fine.Who do the gas companies trust to do just that? Answer;Everyone in the country who supplies a meter reading...

 

[Guitarist]

I don't think we're even supposed to remove a single cover on a gas boiler. Unlike heating engineers who play with/modify electrics to suit their own needs.