Extra wire causing havoc! Help

[vhooda]

Firbird Combi 90, Flow Switch Sticking
Hi Guys, I have messed up my boiler this time, or thats what the electrician thinks.
My boiler worked perfectly untill 2 weeks back when I decided to have a look at my mechanical timer which was getting stuck in cold weather. I took the timer out nubered the wires to put that back, opened the timer and put it all together untill happy that it was now moving freely. I put it back in to realize I had pulled out another brown wire form somewhere and nothing was working now, no ch no dhw.
The wire was comming from the relay and had to call a trusted electrician to have a look. He couldnt make out whaere it came from as nothing seemed pulled but decided to rewire it according to the wire diagram. According to him this wire was a different colour to other brown wires and seemed like it had been added later to the boiler i.e afer intial factory wiring.

Since then I have gone through three flow switches, it works fine for about 24 hrs then the flow switch gets stuck and central heating pump wont start as it thinks I am calling for hot water( I dont think this model has a diverter valve, it just switches pumps) Now, if I disengage the flow switch central heating starts otherwise relay constantly stays stuck in on position.

Electrician is at a loss whats causing it? I have replaced two flow swithches at £67 each. What are we missing??

 

[Dan Robinson]

What are we missing??

Someone who knows what they're doing. Give up and pay a professional boiler repair man. Sparkies know little or nothing about boilers.

 

[vhooda]

Boiler man says it needs professional electrician, what I posted is electrician's experiance, I just found the extra wire right in the begining.Help!

 

[matt1e]

Firbird Combi 90, Flow Switch Sticking
Hi Guys, I have messed up my boiler this time, or thats what the electrician thinks.

The wire was comming from the relay and had to call a trusted electrician to have a look. He couldnt make out whaere it came from as nothing seemed pulled but decided to rewire it according to the wire diagram. According to him this wire was a different colour to other brown wires and seemed like it had been added later to the boiler i.e afer intial factory wiring.

If he had the wiring diagram and presumably a multimeter then how couldn't he make out where it was coming from?

Since then I have gone through three flow switches, it works fine for about 24 hrs then the flow switch gets stuck and central heating pump wont start as it thinks I am calling for hot water( I dont think this model has a diverter valve, it just switches pumps) Now, if I disengage the flow switch central heating starts otherwise relay constantly stays stuck in on position.

are you sure the flow switches are at fault ie are the old ones now testing permanently closed?
are you sure it is the flow switch you are disengaging?
where, how, are you disengaging it?
the heatstore stat will also pull the relay in as it is wired in parallel with the flow switch

Electrician is at a loss whats causing it? I have replaced two flow swithches at £67 each. What are we missing??

test the old switches for continuity with a multimeter and report back

Matt

 

[vhooda]

Hi,
Thanks Matt, my knowlidge is pretty basic, I just pull one brown wire out of the two going to the flow switch, this used to disengage the relay on my first flow switch and ch would start. The last flow switch was tested and found to be sticking occasionly with the multimeter.

With the new flow swith the relay gets engaged as soon as I reconnect the flow switch and then I have to disengage flow switch plus switch the boiler off and on before relay disengages.

What I cant understand is why does it work ok for 24 hrs after changing the flow switch?? I will test the new flow switch and let you know>

Thanks

 

[matt1e]

With the new flow swith the relay gets engaged as soon as I reconnect the flow switch and then I have to disengage flow switch plus switch the boiler off and on before relay disengages.

there's your problem (in bold)
your sparky has messed the rewiring of your boiler up
hes somehow rewired it so the relay is self latching
if he has wired it correctly then it is the heatstore stat that is latching it

there is a complete wiring diagram available for your boiler get him back to sort it if you trust him (we can all make mistakes so he may be ok )or somebody that knows what they're doing If he feels he's out of his depth

he needs to find out where the voltage that will be on A1 of the relay base after you have disconected the flow switch is coming from
check the heat store stat first (the manual calls it a "relay tank")

Matt

 

[matt1e]

You can download a manual with the wiring and circuit diagrams in
Here

 

[vhooda]

Thanks matt1e

Its a combi 90, I have the wire diagram for it.

 

[vhooda]

Hi matt,

Electrician came around and had a look, flow switch is gone again. It looks like its getting additional current and the flow switch itself is 1amp.
I have ordered a new switch and he is going to look at the wiring again before putting the new one on.

Cheers!

 

[matt1e]

Hi matt,

Electrician came around and had a look, flow switch is gone again. It looks like its getting additional current and the flow switch itself is 1amp.
I have ordered a new switch and he is going to look at the wiring again before putting the new one on.

Cheers!

the only thing drawing current through the flow switch should be the relay's coil
I suspect that motor current is being drawn through it due to mis-wiring of the relay base, which would weld the the contacts in the flow switch together in no time at all
he needs to start again and make sure the coil operating connections are correct
how much of the boiler did he rewire?
was it just the timer connections or the relay or both?

 

[Agile]

How is it that 90% of my customers would expect ME to be paying for replacement flow switches if my faulty wiring had caused them to fail !

In fact it would be 100% but perhaps 10% would be kind?

To be honest I dont know do I because I dont make a habit of wrongly wiring anything. I check at least three times!

Tony

 

[vhooda]

I think I am that 10% of your customers Agile who would foot the bill if electrician makes a genuine mistake especially as we work for the same woderful organization. Keeping in mind his labour costs are nothing compared to what you would charge your customers, there is no per hour business here.

In respone to what Matt said, he did not rewire the timer as I had already got tit figured out and put them back a I had nubered them. Its this extra wire which had come off from somewhere behind the timer when I was putting the timer back in. He looked at the wire diagram and the extra wire did not make sense to him, he thought it was a late addition by someone clever as it was of different brown colour. so he took it off all togther and wired it again form the relay according to the wire diagram. Since then the flow switches have started welding.

 

[Agile]

I think I am that 10% of your customers Agile who would foot the bill if electrician makes a genuine mistake especially as we work for the same woderful organization. Keeping in mind his labour costs are nothing compared to what you would charge your customers, there is no per hour business here.

I do all repairs on a fixed charge basis plus parts and so there is no per hour charge. I dont even have a figure to give to anyone!

Thats even if I had to make a second visit to bring a part which I did not have in stock!

I suppose that with you displacing this wire there is some argument that you had an input to the faulty operation.

However, as far as we can see, he has NOT wired it according to the manufacturer's diagram!

Tony

 

[vhooda]

Hi matt,

problem not resolved yet. Sparky came and rechecked all the wiring again. He worked out with his clip on meter the amp going to the flow switch was 0.1amp without relay being engaged and 0.2 amp when relay pulled in.Put the new flow switch on ( third one). It seemed to be working fine for some time but the relay was already starting to latch whenever hot water was turned on but would release after a long while i.e about 5-7 min. Within 24 hrs the relay is not disengaging at all until boiler is switched off and on.

Every time I turn the hot water on, I have to go out and switch the boiler on and off to disengage the relay and get the heating back on as CH pump does not start until relay disengages.
Came home today to find the relay already engaged with no CH although I disengaged it in the morning and went probaby when boiler must have fired to top up it reserve during the day.
Now I am not sure whether the other two flow switches have really gone or not (Something you mentioned right in the begining)

Sparky thinks its one of the stats which is gone but not the relay tank stat but the one next to it( I forgot the name).

I think we are still missing a wire from the relay back to one of these stats
i.e RTS or the other one which lie directly behind the timer where I was fiddling before it got pulled out. He removed it alltogether and went by the diagram.

Would be intrested to know what you think. Your help is greatly appreciated and I keep giving your ideas to sparky as well.

Thanks

 

[bhm1712]

The wiring is wrong, its obvious.

Somebody needs to start tracing cables and continuity testing to find out at BOTH ends where the cables go to now,and where they should be going.

Using a clamp on ammeter to measure current is not telling anybody anything other than current is being drawn. It does not mean its wired correctly.

It worked (apart from mechanical timer getting stuck) before you removed it, so if it was wired correctly it would work ok now.