I've got an old boiler, and when I shut it off last summer for 6 months, I had to bleed the air out of the gas line before I could light the pilot. This year the pilot is staying on. How do modern boilers cope which have electronic ignition?

On Monday, 23 May 2016 01:09:48 UTC+1, Mr Macaw wrote:
I've got an old boiler, and when I shut it off last summer for 6 months, I had to bleed the air out of the gas line before I could light the pilot. This year the pilot is staying on. How do modern boilers cope which have electronic ignition?

Air in the gas line, if it appeared spontaneously, is a dangerous fault.

On 23/05/2016 01:09, Mr Macaw wrote:
I've got an old boiler, and when I shut it off last summer for 6 months,
I had to bleed the air out of the gas line before I could light the
pilot. This year the pilot is staying on. How do modern boilers cope
which have electronic ignition?

The pipework is purged when installing it in the first place. The boiler
itself can also do a small purge sequence during ignition. If it fails
to light then it will retry that a number of times before locking out.
That's normally enough to clear any air, although sometime you may need
to reset it and allow it to try again if there is lots of air to clear.

In normal circumstances there ought not be any air anyway unless the
pipework has been worked on...


--
Cheers,

John.

/================================================== ===============\
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\================================================= ================/

On Mon, 23 May 2016 11:14:03 +0100, John Rumm wrote:

On 23/05/2016 01:09, Mr Macaw wrote:
I've got an old boiler, and when I shut it off last summer for 6 months,
I had to bleed the air out of the gas line before I could light the
pilot. This year the pilot is staying on. How do modern boilers cope
which have electronic ignition?

The pipework is purged when installing it in the first place. The boiler
itself can also do a small purge sequence during ignition. If it fails
to light then it will retry that a number of times before locking out.
That's normally enough to clear any air, although sometime you may need
to reset it and allow it to try again if there is lots of air to clear..

When I had my boiler off for 6 months, it took me 30 minutes of pressing the ignition switch to purge it. The pilot doesn't let much through.

Or would an automatic boiler let more through using the main jets? Could it perhaps tell the difference between gas and air?

In normal circumstances there ought not be any air anyway unless the
pipework has been worked on...

Yeah.... pipes are 100.00000% leakproof and the gas coming into your house is 100.00000% pure....

--
Whats black, white, and red all over and doesnt fit through a revolving door?
A nun with a spear through her head.

On Mon, 23 May 2016 06:52:31 +0100, harry wrote:

On Monday, 23 May 2016 01:09:48 UTC+1, Mr Macaw wrote:
I've got an old boiler, and when I shut it off last summer for 6 months, I had to bleed the air out of the gas line before I could light the pilot. This year the pilot is staying on. How do modern boilers cope which have electronic ignition?

Air in the gas line, if it appeared spontaneously, is a dangerous fault.

I said "6 months".

--
A bloke walks into a Glasgow library and says to the prim librarian,
"Excuse me Miss, dey ye hae ony books on suicide?"
To which she stops doing her tasks, looks at him over the top of her glasses and says,
"Buggeroff, ye'll no bring it back!"

On 23/05/2016 15:43, Mr Macaw wrote:

In normal circumstances there ought not be any air anyway unless the
pipework has been worked on...

Yeah.... pipes are 100.00000% leakproof and the gas coming into your
house is 100.00000% pure....


Sigh. The gas inside the pipe is under pressure, so if you turn the gas
off at the main and there's a small leak, it's true that the gas
pressure in the pipe would reduce to 1 atmosphere over time. However,
there's a world of difference between that and a significant quantity of
air diffusing into the pipe.

On Mon, 23 May 2016 16:28:36 +0100, GB wrote:

On 23/05/2016 15:43, Mr Macaw wrote:

In normal circumstances there ought not be any air anyway unless the
pipework has been worked on...

Yeah.... pipes are 100.00000% leakproof and the gas coming into your
house is 100.00000% pure....


Sigh. The gas inside the pipe is under pressure, so if you turn the gas
off at the main and there's a small leak, it's true that the gas
pressure in the pipe would reduce to 1 atmosphere over time. However,
there's a world of difference between that and a significant quantity of
air diffusing into the pipe.

I forgot I'd turned it off at the lever by the meter. I was thinking air was collecting in the boiler pipe while the cooker was used, but I changed it to an electric cooker!

Well I can tell you there was a LOT of air in the pipe after 6 months of being closed at both ends. Perhaps the boiler pilot or the main valve by the meter leaks very slowly, after all 6 months is a VERY long time. It certainly isn't leaking enough to smell any gas. And I doubt anyone has 100.00% leak proof pipes over 6 months, just like your car tyre won't stay up forever.

--
"A life without danger is a life not worth living" -- Moist von Lipwig

On 23/05/2016 16:56, Mr Macaw wrote:
On Mon, 23 May 2016 16:28:36 +0100, GB wrote:

On 23/05/2016 15:43, Mr Macaw wrote:

In normal circumstances there ought not be any air anyway unless the
pipework has been worked on...

Yeah.... pipes are 100.00000% leakproof and the gas coming into your
house is 100.00000% pure....


Sigh. The gas inside the pipe is under pressure, so if you turn the gas
off at the main and there's a small leak, it's true that the gas
pressure in the pipe would reduce to 1 atmosphere over time. However,
there's a world of difference between that and a significant quantity of
air diffusing into the pipe.

I forgot I'd turned it off at the lever by the meter. I was thinking
air was collecting in the boiler pipe while the cooker was used, but I
changed it to an electric cooker!

Well I can tell you there was a LOT of air in the pipe after 6 months of
being closed at both ends. Perhaps the boiler pilot or the main valve
by the meter leaks very slowly, after all 6 months is a VERY long time.
It certainly isn't leaking enough to smell any gas. And I doubt anyone
has 100.00% leak proof pipes over 6 months, just like your car tyre
won't stay up forever.

Unfortunately, you are effectively assuming that your car tyre would
pump itself up. You're not daft enough to think that would happen to a
car tyre but for some reason you think it could happen to your gas pipes.

On Mon, 23 May 2016 19:52:18 +0100, GB wrote:

On 23/05/2016 16:56, Mr Macaw wrote:
On Mon, 23 May 2016 16:28:36 +0100, GB wrote:

On 23/05/2016 15:43, Mr Macaw wrote:

In normal circumstances there ought not be any air anyway unless the
pipework has been worked on...

Yeah.... pipes are 100.00000% leakproof and the gas coming into your
house is 100.00000% pure....


Sigh. The gas inside the pipe is under pressure, so if you turn the gas
off at the main and there's a small leak, it's true that the gas
pressure in the pipe would reduce to 1 atmosphere over time. However,
there's a world of difference between that and a significant quantity of
air diffusing into the pipe.

I forgot I'd turned it off at the lever by the meter. I was thinking
air was collecting in the boiler pipe while the cooker was used, but I
changed it to an electric cooker!

Well I can tell you there was a LOT of air in the pipe after 6 months of
being closed at both ends. Perhaps the boiler pilot or the main valve
by the meter leaks very slowly, after all 6 months is a VERY long time.
It certainly isn't leaking enough to smell any gas. And I doubt anyone
has 100.00% leak proof pipes over 6 months, just like your car tyre
won't stay up forever.

Unfortunately, you are effectively assuming that your car tyre would
pump itself up. You're not daft enough to think that would happen to a
car tyre but for some reason you think it could happen to your gas pipes.

Eh? I'm saying that the air leaks out of the tyre over time (i.e. the tyre is not 100% leakproof). In the same way, the pipe is not 100% leakproof, so air will get in and gas will get out. The pressure of mains gas is only very slightly over atmospheric, so once that extra bit of gas has leaked out, air can get in easily enough.

--
The cost of living hasn't affected its popularity.

On 23/05/2016 20:32, Mr Macaw wrote:
On Mon, 23 May 2016 19:52:18 +0100, GB wrote:

On 23/05/2016 16:56, Mr Macaw wrote:
On Mon, 23 May 2016 16:28:36 +0100, GB wrote:

On 23/05/2016 15:43, Mr Macaw wrote:

In normal circumstances there ought not be any air anyway unless the
pipework has been worked on...

Yeah.... pipes are 100.00000% leakproof and the gas coming into your
house is 100.00000% pure....


Sigh. The gas inside the pipe is under pressure, so if you turn the gas
off at the main and there's a small leak, it's true that the gas
pressure in the pipe would reduce to 1 atmosphere over time. However,
there's a world of difference between that and a significant
quantity of
air diffusing into the pipe.

I forgot I'd turned it off at the lever by the meter. I was thinking
air was collecting in the boiler pipe while the cooker was used, but I
changed it to an electric cooker!

Well I can tell you there was a LOT of air in the pipe after 6 months of
being closed at both ends. Perhaps the boiler pilot or the main valve
by the meter leaks very slowly, after all 6 months is a VERY long time.
It certainly isn't leaking enough to smell any gas. And I doubt anyone
has 100.00% leak proof pipes over 6 months, just like your car tyre
won't stay up forever.

Unfortunately, you are effectively assuming that your car tyre would
pump itself up. You're not daft enough to think that would happen to a
car tyre but for some reason you think it could happen to your gas pipes.

Eh? I'm saying that the air leaks out of the tyre over time (i.e. the
tyre is not 100% leakproof). In the same way, the pipe is not 100%
leakproof, so air will get in and gas will get out. The pressure of
mains gas is only very slightly over atmospheric, so once that extra bit
of gas has leaked out, air can get in easily enough.


Can it?

On Mon, 23 May 2016 21:33:23 +0100, GB wrote:

On 23/05/2016 20:32, Mr Macaw wrote:
On Mon, 23 May 2016 19:52:18 +0100, GB wrote:

On 23/05/2016 16:56, Mr Macaw wrote:
On Mon, 23 May 2016 16:28:36 +0100, GB wrote:

On 23/05/2016 15:43, Mr Macaw wrote:

In normal circumstances there ought not be any air anyway unless the
pipework has been worked on...

Yeah.... pipes are 100.00000% leakproof and the gas coming into your
house is 100.00000% pure....


Sigh. The gas inside the pipe is under pressure, so if you turn the gas
off at the main and there's a small leak, it's true that the gas
pressure in the pipe would reduce to 1 atmosphere over time. However,
there's a world of difference between that and a significant
quantity of
air diffusing into the pipe.

I forgot I'd turned it off at the lever by the meter. I was thinking
air was collecting in the boiler pipe while the cooker was used, but I
changed it to an electric cooker!

Well I can tell you there was a LOT of air in the pipe after 6 months of
being closed at both ends. Perhaps the boiler pilot or the main valve
by the meter leaks very slowly, after all 6 months is a VERY long time.
It certainly isn't leaking enough to smell any gas. And I doubt anyone
has 100.00% leak proof pipes over 6 months, just like your car tyre
won't stay up forever.

Unfortunately, you are effectively assuming that your car tyre would
pump itself up. You're not daft enough to think that would happen to a
car tyre but for some reason you think it could happen to your gas pipes.

Eh? I'm saying that the air leaks out of the tyre over time (i.e. the
tyre is not 100% leakproof). In the same way, the pipe is not 100%
leakproof, so air will get in and gas will get out. The pressure of
mains gas is only very slightly over atmospheric, so once that extra bit
of gas has leaked out, air can get in easily enough.


Can it?

Unless you have 100.00% leakproof pipes, of course. And mine did (or the boiler pilot or main shut off valve did).

--
Interesting fact number 476:
80% of millionaires drive used cars.

On 23/05/16 21:33, GB wrote:
On 23/05/2016 20:32, Mr Macaw wrote:
On Mon, 23 May 2016 19:52:18 +0100, GB wrote:

On 23/05/2016 16:56, Mr Macaw wrote:
On Mon, 23 May 2016 16:28:36 +0100, GB
wrote:

On 23/05/2016 15:43, Mr Macaw wrote:

In normal circumstances there ought not be any air anyway unless the
pipework has been worked on...

Yeah.... pipes are 100.00000% leakproof and the gas coming into your
house is 100.00000% pure....


Sigh. The gas inside the pipe is under pressure, so if you turn the
gas
off at the main and there's a small leak, it's true that the gas
pressure in the pipe would reduce to 1 atmosphere over time. However,
there's a world of difference between that and a significant
quantity of
air diffusing into the pipe.

I forgot I'd turned it off at the lever by the meter. I was thinking
air was collecting in the boiler pipe while the cooker was used, but I
changed it to an electric cooker!

Well I can tell you there was a LOT of air in the pipe after 6
months of
being closed at both ends. Perhaps the boiler pilot or the main valve
by the meter leaks very slowly, after all 6 months is a VERY long time.
It certainly isn't leaking enough to smell any gas. And I doubt anyone
has 100.00% leak proof pipes over 6 months, just like your car tyre
won't stay up forever.

Unfortunately, you are effectively assuming that your car tyre would
pump itself up. You're not daft enough to think that would happen to a
car tyre but for some reason you think it could happen to your gas
pipes.

Eh? I'm saying that the air leaks out of the tyre over time (i.e. the
tyre is not 100% leakproof). In the same way, the pipe is not 100%
leakproof, so air will get in and gas will get out. The pressure of
mains gas is only very slightly over atmospheric, so once that extra bit
of gas has leaked out, air can get in easily enough.


Can it?


No.


--
"When one man dies it's a tragedy. When thousands die it's statistics."

Josef Stalin

On Mon, 23 May 2016 22:22:18 +0100, The Natural Philosopher wrote:

On 23/05/16 21:33, GB wrote:
On 23/05/2016 20:32, Mr Macaw wrote:
On Mon, 23 May 2016 19:52:18 +0100, GB wrote:

On 23/05/2016 16:56, Mr Macaw wrote:
On Mon, 23 May 2016 16:28:36 +0100, GB
wrote:

On 23/05/2016 15:43, Mr Macaw wrote:

In normal circumstances there ought not be any air anyway unless the
pipework has been worked on...

Yeah.... pipes are 100.00000% leakproof and the gas coming into your
house is 100.00000% pure....


Sigh. The gas inside the pipe is under pressure, so if you turn the
gas
off at the main and there's a small leak, it's true that the gas
pressure in the pipe would reduce to 1 atmosphere over time. However,
there's a world of difference between that and a significant
quantity of
air diffusing into the pipe.

I forgot I'd turned it off at the lever by the meter. I was thinking
air was collecting in the boiler pipe while the cooker was used, but I
changed it to an electric cooker!

Well I can tell you there was a LOT of air in the pipe after 6
months of
being closed at both ends. Perhaps the boiler pilot or the main valve
by the meter leaks very slowly, after all 6 months is a VERY long time.
It certainly isn't leaking enough to smell any gas. And I doubt anyone
has 100.00% leak proof pipes over 6 months, just like your car tyre
won't stay up forever.

Unfortunately, you are effectively assuming that your car tyre would
pump itself up. You're not daft enough to think that would happen to a
car tyre but for some reason you think it could happen to your gas
pipes.

Eh? I'm saying that the air leaks out of the tyre over time (i.e. the
tyre is not 100% leakproof). In the same way, the pipe is not 100%
leakproof, so air will get in and gas will get out. The pressure of
mains gas is only very slightly over atmospheric, so once that extra bit
of gas has leaked out, air can get in easily enough.


Can it?


No.

What makes you think this?


--
Q: If you have a mothball in one hand and another mothball in the other hand, what would you have?
A: The undivided attention of a very large moth!

On Monday, 23 May 2016 15:44:06 UTC+1, Mr Macaw wrote:
On Mon, 23 May 2016 06:52:31 +0100, harry wrote:

On Monday, 23 May 2016 01:09:48 UTC+1, Mr Macaw wrote:
I've got an old boiler, and when I shut it off last summer for 6 months, I had to bleed the air out of the gas line before I could light the pilot. This year the pilot is staying on. How do modern boilers cope which have electronic ignition?

Air in the gas line, if it appeared spontaneously, is a dangerous fault.

I said "6 months".

--
A bloke walks into a Glasgow library and says to the prim librarian,
"Excuse me Miss, dey ye hae ony books on suicide?"
To which she stops doing her tasks, looks at him over the top of her glasses and says,
"Buggeroff, ye'll no bring it back!"

Don't you know what "spontaneously" means?

On Tue, 24 May 2016 07:40:25 +0100, harry wrote:

On Monday, 23 May 2016 15:44:06 UTC+1, Mr Macaw wrote:
On Mon, 23 May 2016 06:52:31 +0100, harry wrote:

On Monday, 23 May 2016 01:09:48 UTC+1, Mr Macaw wrote:
I've got an old boiler, and when I shut it off last summer for 6 months, I had to bleed the air out of the gas line before I could light the pilot. This year the pilot is staying on. How do modern boilers cope which have electronic ignition?

Air in the gas line, if it appeared spontaneously, is a dangerous fault.

I said "6 months".

--
A bloke walks into a Glasgow library and says to the prim librarian,
"Excuse me Miss, dey ye hae ony books on suicide?"
To which she stops doing her tasks, looks at him over the top of her glasses and says,
"Buggeroff, ye'll no bring it back!"

Don't you know what "spontaneously" means?

Yes, and it didn't happen in what we're discussing, as 6 months was available for it to appear.

--
110 people once tied for second prize in the Powerball Lottery after playing the same lucky numbers from a fortune cookie.

On 23/05/2016 19:52, GB wrote:

Unfortunately, you are effectively assuming that your car tyre would
pump itself up. You're not daft enough to think that would happen to a
car tyre but for some reason you think it could happen to your gas pipes.

It's not the same at all.

If you have a closed vessel with a pinprick opening then whenever there
is a low or high and the pressure changes a little bit of the contents
will come out, or air go in.

Once in diffusion will mix the gasses.

Andy

On 26/05/2016 20:50, Vir Campestris wrote:
On 23/05/2016 19:52, GB wrote:

Unfortunately, you are effectively assuming that your car tyre would
pump itself up. You're not daft enough to think that would happen to a
car tyre but for some reason you think it could happen to your gas pipes.

It's not the same at all.

If you have a closed vessel with a pinprick opening then whenever there
is a low or high and the pressure changes a little bit of the contents
will come out, or air go in.

Once in diffusion will mix the gasses.

Andy


Good point, and one I hadn't thought of.

Just to put some figures on it, let's assume 3% of the gas in the vessel
becomes replaced by air each week. (That's roughly consistent with a
weather map I was looking at with pressure ranging from 1020 to 990.)

Then after 26 weeks, the proportion of gas in the pipe will be 0.97^26 =
45%.

On Thu, 26 May 2016 22:19:34 +0100, GB wrote:

On 26/05/2016 20:50, Vir Campestris wrote:
On 23/05/2016 19:52, GB wrote:

Unfortunately, you are effectively assuming that your car tyre would
pump itself up. You're not daft enough to think that would happen to a
car tyre but for some reason you think it could happen to your gas pipes.

It's not the same at all.

If you have a closed vessel with a pinprick opening then whenever there
is a low or high and the pressure changes a little bit of the contents
will come out, or air go in.

Once in diffusion will mix the gasses.

Andy


Good point, and one I hadn't thought of.

Just to put some figures on it, let's assume 3% of the gas in the vessel
becomes replaced by air each week. (That's roughly consistent with a
weather map I was looking at with pressure ranging from 1020 to 990.)

How does the weather map know how big my leak is? It's small enough that I cannot smell gas.

Then after 26 weeks, the proportion of gas in the pipe will be 0.97^26 =
45%.

Sounds about right, the pilot refused to light until I'd attempted it almost continuously for 20-30 minutes. The piping from the meter onwards is about 13.5 metres, 15mm pipe. Two thirds goes to the boiler, one third to what used to be a gas cooker, and is now a self-closed attachment on the end of the pipe. Maybe they don't self close properly?

--
A chicken crossing the road is poultry in motion.

"Mr Macaw" wrote in message news
On Thu, 26 May 2016 22:19:34 +0100, GB wrote:

On 26/05/2016 20:50, Vir Campestris wrote:
On 23/05/2016 19:52, GB wrote:

Unfortunately, you are effectively assuming that your car tyre would
pump itself up. You're not daft enough to think that would happen to a
car tyre but for some reason you think it could happen to your gas
pipes.

It's not the same at all.

If you have a closed vessel with a pinprick opening then whenever there
is a low or high and the pressure changes a little bit of the contents
will come out, or air go in.

Once in diffusion will mix the gasses.

Andy


Good point, and one I hadn't thought of.

Just to put some figures on it, let's assume 3% of the gas in the vessel
becomes replaced by air each week. (That's roughly consistent with a
weather map I was looking at with pressure ranging from 1020 to 990.)

How does the weather map know how big my leak is?

Doesn't need to, any leak will see the inside pressure
follow the outside pressure in that situation.

It's small enough that I cannot smell gas.

You wouldn't expect to smell a 3% leak every week.

Then after 26 weeks, the proportion of gas in the pipe will be 0.97^26 =
45%.

Sounds about right, the pilot refused to light until I'd attempted it
almost continuously for 20-30 minutes. The piping from the meter onwards
is about 13.5 metres, 15mm pipe. Two thirds goes to the boiler, one third
to what used to be a gas cooker, and is now a self-closed attachment on
the end of the pipe. Maybe they don't self close properly?

Or yours doesn't anyway.