Hello, wonder whether anyone can help. One day out of the blue, when my
ho****er system was programmed to come on, it tripped out the main
power switch to the whole house. This started to become randomly more
frequent. I replaced the programmer which I believed to be at fault,
but this made no difference. I tried isolating the pump/valve and
cylinder stat each in turn to identify the problem and this seemed to
point to the cylinder stat. I replaced this but this still hasn't fixed
it.
Now I can turn the hw or ch heating on without it tripping,by turning
the power on when the cylinder stat is on low, and then by turning the
stat up, the boiler will fire up.

Does anyone know how i can solve this strange problem? A heating
engineer came round a while ago when the system was behaving itself and
he couldn't recreate the problem, but i still had to pay a call out
charge !

In an earlier contribution to this discussion,
wrote:

Hello, wonder whether anyone can help. One day out of the blue, when
my ho****er system was programmed to come on, it tripped out the main
power switch to the whole house. This started to become randomly more
frequent. I replaced the programmer which I believed to be at fault,
but this made no difference. I tried isolating the pump/valve and
cylinder stat each in turn to identify the problem and this seemed to
point to the cylinder stat. I replaced this but this still hasn't
fixed it.
Now I can turn the hw or ch heating on without it tripping,by turning
the power on when the cylinder stat is on low, and then by turning the
stat up, the boiler will fire up.

Does anyone know how i can solve this strange problem? A heating
engineer came round a while ago when the system was behaving itself
and he couldn't recreate the problem, but i still had to pay a call
out charge !

Is it tripping an over-current device or an earth leakage device?

What type of control system do you have? [Does it correspond with one of the
'plans' shown in http://content.honeywell.com/uk/homes/systems.htm ? If so,
which one?]

If it's an earth leakage trip (RCD), and if it's a fully pumped system
(S-Plan or Y-Plan), my first port of call would be the pump. It is not
uncommon for pumps to develop intermittent earth faults before failing
completely.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
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Roger Mills wrote:
In an earlier contribution to this discussion,
wrote:

Hello, wonder whether anyone can help. One day out of the blue, when
my ho****er system was programmed to come on, it tripped out the main
power switch to the whole house. This started to become randomly more
frequent. I replaced the programmer which I believed to be at fault,
but this made no difference. I tried isolating the pump/valve and
cylinder stat each in turn to identify the problem and this seemed to
point to the cylinder stat. I replaced this but this still hasn't
fixed it.
Now I can turn the hw or ch heating on without it tripping,by turning
the power on when the cylinder stat is on low, and then by turning the
stat up, the boiler will fire up.

Does anyone know how i can solve this strange problem? A heating
engineer came round a while ago when the system was behaving itself
and he couldn't recreate the problem, but i still had to pay a call
out charge !

RCD tripping means something on the CH is leaking current from live to
earth, or less likely from N to E. Its a lot cheaper to get a
multimeter and find out which item is faulty (some conduction from L&N
to E) than it is to replace everything randomly.


NT

Thanks Roger and NT.
Yes randomly replacing parts is getting expensive ! Looks like I am a Y
plan, and it is the RCD which is tripping. I think I shall invest in a
multimeter and see if that helps. Many thanks.

Thanks Roger and NT.
Yes randomly replacing parts is getting expensive ! Looks like I am a Y
plan, and it is the RCD which is tripping. I think I shall invest in a
multimeter and see if that helps. Many thanks.

In an earlier contribution to this discussion,
wrote:

Thanks Roger and NT.
Yes randomly replacing parts is getting expensive ! Looks like I am a
Y plan, and it is the RCD which is tripping. I think I shall invest
in a multimeter and see if that helps. Many thanks.

In that case, my money's definitely on the pump.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

In an earlier contribution to this discussion,
wrote:

Thanks Roger and NT.
Yes randomly replacing parts is getting expensive ! Looks like I am a
Y plan, and it is the RCD which is tripping. I think I shall invest
in a multimeter and see if that helps. Many thanks.

One multimeter should be enough - you don't need two! g
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

Roger Mills wrote:

One multimeter should be enough - you don't need two! g
--

you ought to tell him what to do with it. A multimeter in a novices
hands is like JCB in the hands of a drunken man.

In an earlier contribution to this discussion,
wrote:

Roger Mills wrote:

One multimeter should be enough - you don't need two! g
--

you ought to tell him what to do with it. A multimeter in a novices
hands is like JCB in the hands of a drunken man.

Actually, I'm not sure that a multimeter is going to help.

For an earth leak (most likely in the pump) to trip a 30mA RCD, there would
have to be an impedance of less than about 8k Ohms between live and earth. A
multi meter will measure the DC resistance, but I'm not sure that that is
the same thing - and the fault seems to be intermittent anyway.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

Roger Mills wrote:
Actually, I'm not sure that a multimeter is going to help.

For an earth leak (most likely in the pump) to trip a 30mA RCD, there would
have to be an impedance of less than about 8k Ohms between live and earth. A
multi meter will measure the DC resistance, but I'm not sure that that is
the same thing - and the fault seems to be intermittent anyway.
--
I agree its tricky to find the fault.
I had an mcb trip out last week and after a lot of searching I found
the problem was a squirrel had bitten a cable that crossed a tree plus
it was a wet day only when it tripped. It a bit of detective work to
find.

Roger Mills wrote:
Actually, I'm not sure that a multimeter is going to help.

For an earth leak (most likely in the pump) to trip a 30mA RCD, there would
have to be an impedance of less than about 8k Ohms between live and earth. A
multi meter will measure the DC resistance, but I'm not sure that that is
the same thing - and the fault seems to be intermittent anyway.
--
I agree its tricky to find the fault.
I had an mcb on a line to a pump trip out last week and after a lot of
searching I found the problem was a squirrel had bitten a cable that
crossed a tree plus it was a wet day only when it tripped. It took a
bit of detective work before I found the fault.

I think he should go over every bit of wiring he has first and look
carefully at the connections and check screws are tight and cables look
in the right place etc etc before he starts anything else. Then check
the board for any flaws. It could be a bevy of spiders webs or a dead
mouse in the back of the board so a good inspection of everything is
elementary first.

Roger Mills wrote:
In an earlier contribution to this discussion,
wrote:

Roger Mills wrote:
One multimeter should be enough - you don't need two! g
--
you ought to tell him what to do with it. A multimeter in a novices
hands is like JCB in the hands of a drunken man.

Actually, I'm not sure that a multimeter is going to help.

For an earth leak (most likely in the pump) to trip a 30mA RCD, there would
have to be an impedance of less than about 8k Ohms between live and earth. A
multi meter will measure the DC resistance, but I'm not sure that that is
the same thing - and the fault seems to be intermittent anyway.

It most certainly will measure that, and the DC resistance is usually
what you get in a fault condition.


Intermittent is less easy to spot.

In an earlier contribution to this discussion,
The Natural Philosopher wrote:

Roger Mills wrote:
In an earlier contribution to this discussion,

For an earth leak (most likely in the pump) to trip a 30mA RCD,
there would have to be an impedance of less than about 8k Ohms
between live and earth. A multi meter will measure the DC
resistance, but I'm not sure that that is the same thing - and the
fault seems to be intermittent anyway.

It most certainly will measure that, and the DC resistance is usually
what you get in a fault condition.

I'm not so sure! If the fault is caused by the presence of water in the
wrong place - which it may well be - my impression is that water behaves
differently at mains AC voltage from what it does at low DC voltage.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

Roger Mills wrote:
In an earlier contribution to this discussion,
The Natural Philosopher wrote:

Roger Mills wrote:
In an earlier contribution to this discussion,

For an earth leak (most likely in the pump) to trip a 30mA RCD,
there would have to be an impedance of less than about 8k Ohms
between live and earth. A multi meter will measure the DC
resistance, but I'm not sure that that is the same thing - and the
fault seems to be intermittent anyway.
It most certainly will measure that, and the DC resistance is usually
what you get in a fault condition.

I'm not so sure! If the fault is caused by the presence of water in the
wrong place - which it may well be - my impression is that water behaves
differently at mains AC voltage from what it does at low DC voltage.

No. Its about the same. You can stick meter probes in a glass of water
and see the resistance OK.

Only insulation breakdown by arcing/sparking needs a high voltage to
make it happen...but that CAN be DC as well.

Only capacitors e.g. in RF filters behave differently under AC to
DC..but they seldom fail by increasing capacity..usually they short and
go BANG instead.

The Natural Philosopher wrote:
Roger Mills wrote:
In an earlier contribution to this discussion,
The Natural Philosopher wrote:

Roger Mills wrote:
In an earlier contribution to this discussion,

For an earth leak (most likely in the pump) to trip a 30mA RCD,
there would have to be an impedance of less than about 8k Ohms
between live and earth. A multi meter will measure the DC
resistance, but I'm not sure that that is the same thing - and the
fault seems to be intermittent anyway.
It most certainly will measure that, and the DC resistance is usually
what you get in a fault condition.

I'm not so sure! If the fault is caused by the presence of water in the
wrong place - which it may well be - my impression is that water behaves
differently at mains AC voltage from what it does at low DC voltage.

No. Its about the same. You can stick meter probes in a glass of water
and see the resistance OK.

Only insulation breakdown by arcing/sparking needs a high voltage to
make it happen...but that CAN be DC as well.

Only capacitors e.g. in RF filters behave differently under AC to
DC..but they seldom fail by increasing capacity..usually they short and
go BANG instead.

To be pedantic, inductors (eg in shaver socket transformers) also
behave differently under AC to DC ... but that doesn't alter the main
point that a) the difference between low-voltage and high-voltage is
more significant than between AC and DC; b) domestic water behaves
pretty much according to Ohms law so a multimeter should be fine. (I'm
not convinced high purity distilled water with low disolved gasses
would behave ohmically, but that's getting /really/ pedantic).

Martin Bonner wrote:
The Natural Philosopher wrote:
Roger Mills wrote:
In an earlier contribution to this discussion,
The Natural Philosopher wrote:

Roger Mills wrote:
In an earlier contribution to this discussion,

For an earth leak (most likely in the pump) to trip a 30mA RCD,
there would have to be an impedance of less than about 8k Ohms
between live and earth. A multi meter will measure the DC
resistance, but I'm not sure that that is the same thing - and the
fault seems to be intermittent anyway.
It most certainly will measure that, and the DC resistance is usually
what you get in a fault condition.

I'm not so sure! If the fault is caused by the presence of water in the
wrong place - which it may well be - my impression is that water behaves
differently at mains AC voltage from what it does at low DC voltage.
No. Its about the same. You can stick meter probes in a glass of water
and see the resistance OK.

Only insulation breakdown by arcing/sparking needs a high voltage to
make it happen...but that CAN be DC as well.

Only capacitors e.g. in RF filters behave differently under AC to
DC..but they seldom fail by increasing capacity..usually they short and
go BANG instead.

To be pedantic, inductors (eg in shaver socket transformers) also
behave differently under AC to DC ... but that doesn't alter the main
point that a) the difference between low-voltage and high-voltage is
more significant than between AC and DC; b) domestic water behaves
pretty much according to Ohms law so a multimeter should be fine. (I'm
not convinced high purity distilled water with low disolved gasses
would behave ohmically, but that's getting /really/ pedantic).

Agreed.But indictors generally get better at not leaking under AC
conditions ;-)

thanks for all your help.
The problem is indeed intemittant when using the programmer to turn the
heating on at the set times, but when i manually start up the hot water
by turning on the power with the cylinder stat on its lowest setting
and then turning the stat temp setting up, it NEVER trips. Surely this
must rule out an intemittant wiring fault ?

thanks for all your help.
The problem is indeed intemittant when using the programmer to turn the

heating on at the set times, but when i manually start up the hot water

by turning on the power with the cylinder stat on its lowest setting
and then turning the stat temp setting up, it NEVER trips. Surely this
must rule out an intemittant wiring fault ?





Reply »

The Natural Philosopher wrote:
Martin Bonner wrote:
The Natural Philosopher wrote:
Roger Mills wrote:
In an earlier contribution to this discussion,
The Natural Philosopher wrote:

Roger Mills wrote:
In an earlier contribution to this discussion,

For an earth leak (most likely in the pump) to trip a 30mA RCD,
there would have to be an impedance of less than about 8k Ohms
between live and earth. A multi meter will measure the DC
resistance, but I'm not sure that that is the same thing - and the
fault seems to be intermittent anyway.
It most certainly will measure that, and the DC resistance is usually
what you get in a fault condition.

I'm not so sure! If the fault is caused by the presence of water in the
wrong place - which it may well be - my impression is that water behaves
differently at mains AC voltage from what it does at low DC voltage.
No. Its about the same. You can stick meter probes in a glass of water
and see the resistance OK.

Only insulation breakdown by arcing/sparking needs a high voltage to
make it happen...but that CAN be DC as well.

Only capacitors e.g. in RF filters behave differently under AC to
DC..but they seldom fail by increasing capacity..usually they short and
go BANG instead.

To be pedantic, inductors (eg in shaver socket transformers) also
behave differently under AC to DC ... but that doesn't alter the main
point that a) the difference between low-voltage and high-voltage is
more significant than between AC and DC; b) domestic water behaves
pretty much according to Ohms law so a multimeter should be fine. (I'm
not convinced high purity distilled water with low disolved gasses
would behave ohmically, but that's getting /really/ pedantic).

Agreed.But indictors generally get better at not leaking under AC
conditions ;-)