Fault finding


C

Colin Freelove

Can anyone help me with this problem ? Below the timmer control and
switches to my boiler is another small light switch type switch with a
fuse in it. The mains seems to run into this switch then on to the
control panel. My first question is what size of fuse should be in
this switch, and secondly when I stand in a certain place on the
landing this causes the house trip to activate, it would seem there is
a wire too close to floor boards which when pressure is applied it
throws the trip. This seems to be the same wire that leeds to boiler
switch. Can anyone help with advice, money is tight at this time.
Thankyou
 
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M

Martin

Colin Freelove said:
Can anyone help me with this problem ? Below the timmer control and
switches to my boiler is another small light switch type switch with a
fuse in it. The mains seems to run into this switch then on to the
control panel. My first question is what size of fuse should be in
this switch, and secondly when I stand in a certain place on the
landing this causes the house trip to activate, it would seem there is
a wire too close to floor boards which when pressure is applied it
throws the trip. This seems to be the same wire that leeds to boiler
switch. Can anyone help with advice, money is tight at this time.
Thankyou
My boiler is fused at 3A.

You will have to take up the floorboards to investigate the tripping fault,
something under there is shorting out.

Martin.
 
L

Lurch

Can anyone help me with this problem ? Below the timmer control and
switches to my boiler is another small light switch type switch with a
fuse in it. The mains seems to run into this switch then on to the
control panel. My first question is what size of fuse should be in
this switch,
A 3A fuse is always used for heating systems.
and secondly when I stand in a certain place on the
landing this causes the house trip to activate, it would seem there is
a wire too close to floor boards which when pressure is applied it
throws the trip.
Sounds likely, best bet would be whip the boards up and (carefully)
find which wire under there is faulty. Hopefully it should be fairly
obvious which one is trapped, or possibly caught by a nail from the
floorboard.
When you find it either repair the faulty piece with a junction box,
or replace the length of cable altogether. It all depends where the
cable runs I suppose as to which way you do it.
this seems to be the same wire that leeds to boiler
switch. Can anyone help with advice, money is tight at this time.
Thankyou
...

SJW
A.C.S. Ltd.
 
M

M. Damerell

On Sun, 22 Feb 2004, Lurch wrote:

[snip]
Sounds likely, best bet would be whip the boards up and (carefully)
find which wire under there is faulty. Hopefully it should be fairly
obvious which one is trapped, or possibly caught by a nail from the
floorboard.
If there is a nail through the cable, I suggest that you turn off at
the mains before trying to pull it.
 
L

Lurch

Not necessarily.

There are a number of boilers which have 4A fuses on the pcb,
That there may be, but no-one mentioned PCB fuses.
Perhaps should have said, 90% of heating systems use a 3A fuse, in the
unlikely event you have a commercially rated heating system check the
manufacturers details.
...

SJW
A.C.S. Ltd.
 
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geoff

Lurch said:
That there may be, but no-one mentioned PCB fuses.
Perhaps should have said, 90% of heating systems use a 3A fuse, in the
unlikely event you have a commercially rated heating system check the
manufacturers details.
..
The fuse on the pcb comes after the main boiler fuse, fuses are there to
protect the wiring, so what's the point of a larger fuse on a subset of
the whole system? The Halstead quattro ignition pcb (which basically
operates the GVs and creates the spark) has a 4 fuse on it.

The fuse on the pcb is a slower blow fuse than the main fuse (no idea
what the main fuse rating on this boiler is)

I'm not talking about commercial boilers here, it would shoot up
drastically if I did
 
L

Lurch

A 3A fuse is always used for heating systems.
The fuse on the pcb comes after the main boiler fuse, fuses are there to
protect the wiring, so what's the point of a larger fuse on a subset of
the whole system? The Halstead quattro ignition pcb (which basically
operates the GVs and creates the spark) has a 4 fuse on it.

The fuse on the pcb is a slower blow fuse than the main fuse (no idea
what the main fuse rating on this boiler is)
I was going to say it's probably a fast blow fuse, until I got to this
bit.
I'm not talking about commercial boilers here, it would shoot up
drastically if I did
You sure the 4A fuse is on the 240V side?
...

SJW
A.C.S. Ltd.
 
G

geoff

Lurch said:
I was going to say it's probably a fast blow fuse, until I got to this
bit.


You sure the 4A fuse is on the 240V side?
..
Having repaired one yesterday, I can categorically say it is.

As I said this is not an isolated case. Not common, but they do exist
 
L

Lurch

Having repaired one yesterday, I can categorically say it is.

As I said this is not an isolated case. Not common, but they do exist
Interesting, I haven't come across a boiler, other than in schools
etc, that dont say in the instructions use a 3A fuse. Having said that
I've just recently wired up 2 huge boilers in a leisure centre, 3A
fuses to each one as per manufacturers spec.
...

SJW
A.C.S. Ltd.
 
M

Martin Angove

In message <[email protected]>,
Interesting, I haven't come across a boiler, other than in schools
etc, that dont say in the instructions use a 3A fuse. Having said that
I've just recently wired up 2 huge boilers in a leisure centre, 3A
fuses to each one as per manufacturers spec.
..
Could it be one of those discrimination things? The 4A on the PCB is
there as a "last resort". In theory in a fault condition the 3A should
blow first, and as this is on the "customer" side of the installation,
it should be easy to fix, and it's a standard BS 1363 fuse too which is
dirt cheap. Perhaps a DIY-er has replaced the valve and misplaced a
wire. If the 3A blows it is relatively easy for him to realise what has
happened, trace and fix the fault and replace the fuse. If the PCB fuse
goes first most DIY-ers would give up and call someone who knows about
boilers.

The 4A is there to be a "non fiddlable" item which protects the
electronics if said DIY-er is completely stupid and sticks a 13A fuse on
his side of things or even wires it up straight to a 16A radial or a
non-fused spur on the ring.

After all, whatever the instructions say, the boiler manufacturers can't
be there to ensure everything is fitted as per the instructions, and
surely it's better to have the PCB fuse blow than to blow a few tracks
and components, thus requiring a new PCB?

Just a thought...

Hwyl!

M.
 
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G

geoff

Lurch said:
I was going to say it's probably a fast blow fuse, until I got to this
bit.


You sure the 4A fuse is on the 240V side?
..
FFS, do you take me for a moron ?
 
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G

geoff

Lurch said:
I do now. unless you were in tongue in cheek mode.
..
Well, I see it as a fairly silly question to ask someone whose business
is repairing pcbs for boilers
 

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