They are doing gas main replacement work in our street.
The information prior to this suggested that the gas people would need
access to check that the boiler was turned off, then access again when the
gas came back on to confirm everything was working.

They just turned it off around 06:30 without any checks.
The CH was still running.
I assume that it failed safe when the gas pressure dropped!

I've switched to frost protect for the moment.

Will the combi boiler just kick back in when gas pressure is returned, or
is it better to turn the power to the boiler off then back on again when
gas pressure is returned?

IIRC when it is powered on after being powered off it runs a purge cycle
before going on to normal operations, but I am not sure if this is just
water, or water and gas.

Cheers

Dave R

--
AMD FX-6300 in GA-990X-Gaming SLI-CF running Windows 7 Pro x64

David wrote:

> They are doing gas main replacement work in our street.
> The information prior to this suggested that the gas people would need
> access to check that the boiler was turned off, then access again when the
> gas came back on to confirm everything was working.
>
> They just turned it off around 06:30 without any checks.
> The CH was still running.
> I assume that it failed safe when the gas pressure dropped!

more likely flame failure device?

> I've switched to frost protect for the moment.

I'd just switch it off, it's not as though it do any frost protecting.

> Will the combi boiler just kick back in when gas pressure is returned, or
> is it better to turn the power to the boiler off then back on again when
> gas pressure is returned?

They ought to do a proper purge before you use any gas appliances, interesting
to know if you have to insist on it

> IIRC when it is powered on after being powered off it runs a purge cycle
> before going on to normal operations, but I am not sure if this is just
> water, or water and gas.

any gas cooker, fire?

David <wibble@btinternet.com> wrote:
> They are doing gas main replacement work in our street.
> The information prior to this suggested that the gas people would need
> access to check that the boiler was turned off, then access again when the
> gas came back on to confirm everything was working.
>
> They just turned it off around 06:30 without any checks.
> The CH was still running.
> I assume that it failed safe when the gas pressure dropped!
>
> I've switched to frost protect for the moment.
>
> Will the combi boiler just kick back in when gas pressure is returned, or
> is it better to turn the power to the boiler off then back on again when
> gas pressure is returned?
>
> IIRC when it is powered on after being powered off it runs a purge cycle
> before going on to normal operations, but I am not sure if this is just
> water, or water and gas.
>

Shouldn’t be an issue with any modern(ish) boiler with electronic ignition.
At worst, if it doesn’t relight quickly enough it may lock-out and will
need a mains power cycle to encourage it to go through the ignition
sequence again.

If you have a gas cooker I’d be inclined to run that first until you have a
steady flame to ensure that the gas mixture has settled down.

Tim

--
Please don't feed the trolls

On Wed, 09 Nov 2022 08:06:47 +0000, Andy Burns wrote:

> David wrote:
>
>> They are doing gas main replacement work in our street.
>> The information prior to this suggested that the gas people would need
>> access to check that the boiler was turned off, then access again when
>> the gas came back on to confirm everything was working.
>>
>> They just turned it off around 06:30 without any checks.
>> The CH was still running.
>> I assume that it failed safe when the gas pressure dropped!
>
> more likely flame failure device?
>
>> I've switched to frost protect for the moment.
>
> I'd just switch it off, it's not as though it do any frost protecting.
>
>> Will the combi boiler just kick back in when gas pressure is returned,
>> or is it better to turn the power to the boiler off then back on again
>> when gas pressure is returned?
>
> They ought to do a proper purge before you use any gas appliances,
> interesting to know if you have to insist on it
>
>> IIRC when it is powered on after being powered off it runs a purge
>> cycle before going on to normal operations, but I am not sure if this
>> is just water, or water and gas.
>
> any gas cooker, fire?

Gas hob.

Cheers

Dave R

--
AMD FX-6300 in GA-990X-Gaming SLI-CF running Windows 7 Pro x64

On Wed, 09 Nov 2022 07:41:21 +0000, David wrote:

> They are doing gas main replacement work in our street.
> The information prior to this suggested that the gas people would need
> access to check that the boiler was turned off, then access again when
> the gas came back on to confirm everything was working.
>
> They just turned it off around 06:30 without any checks.
> The CH was still running.
> I assume that it failed safe when the gas pressure dropped!
>
> I've switched to frost protect for the moment.
>
> Will the combi boiler just kick back in when gas pressure is returned,
> or is it better to turn the power to the boiler off then back on again
> when gas pressure is returned?
>
> IIRC when it is powered on after being powered off it runs a purge cycle
> before going on to normal operations, but I am not sure if this is just
> water, or water and gas.

Interesting to watch.
They have broken the old iron(?) main outside each house and you can see
them pushing the new yellow plastic pipe through from a reel using an
attachment for a small digger.

One other interesting thing.
The yellow pipe from the mains to our meter is small - looks like a garden
hose pipe size.
This is much smaller than the copper from the meter to the boiler and hob.
I assume that the mains is at higher pressure and so doesn't need a larger
bore, which is needed on the other side of the meter to feed the boiler.

Good to replace the old pipe - there have been a few investigations over
the last few years where holes have been bored in the footpath to try and
locate a leak.

Cheers

Dave R

--
AMD FX-6300 in GA-990X-Gaming SLI-CF running Windows 7 Pro x64

On Wed, 09 Nov 2022 08:19:10 +0000, Tim+ wrote:

> David <wibble@btinternet.com> wrote:
>> They are doing gas main replacement work in our street.
>> The information prior to this suggested that the gas people would need
>> access to check that the boiler was turned off, then access again when
>> the gas came back on to confirm everything was working.
>>
>> They just turned it off around 06:30 without any checks.
>> The CH was still running.
>> I assume that it failed safe when the gas pressure dropped!
>>
>> I've switched to frost protect for the moment.
>>
>> Will the combi boiler just kick back in when gas pressure is returned,
>> or is it better to turn the power to the boiler off then back on again
>> when gas pressure is returned?
>>
>> IIRC when it is powered on after being powered off it runs a purge
>> cycle before going on to normal operations, but I am not sure if this
>> is just water, or water and gas.
>>
>>
> Shouldn’t be an issue with any modern(ish) boiler with electronic
> ignition.
> At worst, if it doesn’t relight quickly enough it may lock-out and will
> need a mains power cycle to encourage it to go through the ignition
> sequence again.
>
> If you have a gas cooker I’d be inclined to run that first until you
> have a steady flame to ensure that the gas mixture has settled down.

I've turned it off now.
Despite being on "frost protect" 5C setting a pump was running
I'll wait until everything is on again then run the gas hob for a bit
before I turn it back on.

Cheers

Dave R

--
AMD FX-6300 in GA-990X-Gaming SLI-CF running Windows 7 Pro x64

David wrote:

> The yellow pipe from the mains to our meter is small - looks like a garden
> hose pipe size.
> This is much smaller than the copper from the meter to the boiler and hob.

yes their pipe to the street is on the outside of the regulator (metal can on
the anaconda) is usually up to 75 mbar, your pipe on the inside max 21 mbar.

<https://www.gasproducts.co.uk/media/catalog/product/cache/4aa4c1b6f2e5f7340e387346332f2c01/m/w/mw100-1.png>

David wrote:

> I'll wait until everything is on again then run the gas hob for a bit
> before I turn it back on.

They'll probably visit you to turn it back on.

David <wibble@btinternet.com> wrote:
> They are doing gas main replacement work in our street.
> The information prior to this suggested that the gas people would need
> access to check that the boiler was turned off, then access again when the
> gas came back on to confirm everything was working.
>
> They just turned it off around 06:30 without any checks.
> The CH was still running.
> I assume that it failed safe when the gas pressure dropped!
>
> I've switched to frost protect for the moment.
>
> Will the combi boiler just kick back in when gas pressure is returned, or
> is it better to turn the power to the boiler off then back on again when
> gas pressure is returned?
>
> IIRC when it is powered on after being powered off it runs a purge cycle
> before going on to normal operations, but I am not sure if this is just
> water, or water and gas.
>
> Cheers
>
>
>
> Dave R
>
>
>

I vaguely recall some work being done on the gas pipe / main in a previous
house.

As I recall, we were told/ asked to turn off all gas appliances ( in our
case a boiler an a fire) and wait for someone to call.

Late in the afternoon / early evening ( I think around 5/ 5:30), someone
turned up. From memory, he lit the fire first, then the boiler. Waited a
bit and left.

No big deal, I think it was fairly warm at the time and we weren’t
inconvenienced.

On 09/11/2022 15:22, Brian wrote:
> David <wibble@btinternet.com> wrote:
>> They are doing gas main replacement work in our street.
>> The information prior to this suggested that the gas people would need
>> access to check that the boiler was turned off, then access again when the
>> gas came back on to confirm everything was working.
>>
>> They just turned it off around 06:30 without any checks.
>> The CH was still running.
>> I assume that it failed safe when the gas pressure dropped!
>>
>> I've switched to frost protect for the moment.
>>
>> Will the combi boiler just kick back in when gas pressure is returned, or
>> is it better to turn the power to the boiler off then back on again when
>> gas pressure is returned?
>>
>> IIRC when it is powered on after being powered off it runs a purge cycle
>> before going on to normal operations, but I am not sure if this is just
>> water, or water and gas.
>>
>> Cheers
>>
>>
>>
>> Dave R
>>
>>
>>
>
> I vaguely recall some work being done on the gas pipe / main in a previous
> house.
>
> As I recall, we were told/ asked to turn off all gas appliances ( in our
> case a boiler an a fire) and wait for someone to call.
>
> Late in the afternoon / early evening ( I think around 5/ 5:30), someone
> turned up. From memory, he lit the fire first, then the boiler. Waited a
> bit and left.
>
> No big deal, I think it was fairly warm at the time and we weren’t
> inconvenienced.

We got home from work and found that the guys tasked to turn it back on
had already been down the road and buggered off. Every house where there
was no-one in at the time was left isolated!

We had to phone and demand that someone came out.

SteveW <steve@walker-family.me.uk> wrote:

>
> We got home from work and found that the guys tasked to turn it back on
> had already been down the road and buggered off. Every house where there
> was no-one in at the time was left isolated!
>
> We had to phone and demand that someone came out.

I would’ve just turned the gas back on myself unless they’d locked it off
somehow.

Tim

--
Please don't feed the trolls

On 09/11/2022 09:48, David wrote:
> On Wed, 09 Nov 2022 07:41:21 +0000, David wrote:
>
>> They are doing gas main replacement work in our street.
>> The information prior to this suggested that the gas people would need
>> access to check that the boiler was turned off, then access again when
>> the gas came back on to confirm everything was working.
>>
>> They just turned it off around 06:30 without any checks.
>> The CH was still running.
>> I assume that it failed safe when the gas pressure dropped!
>>
>> I've switched to frost protect for the moment.
>>
>> Will the combi boiler just kick back in when gas pressure is returned,
>> or is it better to turn the power to the boiler off then back on again
>> when gas pressure is returned?
>>
>> IIRC when it is powered on after being powered off it runs a purge cycle
>> before going on to normal operations, but I am not sure if this is just
>> water, or water and gas.
>
> Interesting to watch.
> They have broken the old iron(?) main outside each house and you can see
> them pushing the new yellow plastic pipe through from a reel using an
> attachment for a small digger.
>
> One other interesting thing.
> The yellow pipe from the mains to our meter is small - looks like a garden
> hose pipe size.
> This is much smaller than the copper from the meter to the boiler and hob.
> I assume that the mains is at higher pressure and so doesn't need a larger
> bore, which is needed on the other side of the meter to feed the boiler.

Correct. I think that when they have installed the plastic pipe, they
can increase the supply pressure to the road, allowing the same or more
gas to flow, when needed, despite the plastic pipe reducing the bore so
much, so that the supply pipe does not become a limiting factor for a
combi-boiler, cooker and a couple of fires being on at the same time.

On 09/11/2022 17:14, Tim+ wrote:
> SteveW <steve@walker-family.me.uk> wrote:
>
>>
>> We got home from work and found that the guys tasked to turn it back on
>> had already been down the road and buggered off. Every house where there
>> was no-one in at the time was left isolated!
>>
>> We had to phone and demand that someone came out.
>
> I would’ve just turned the gas back on myself unless they’d locked it off
> somehow.

They left it isolated outside somewhere. I'm sure I could have investigated.

SteveW <steve@walker-family.me.uk> wrote:
> On 09/11/2022 17:14, Tim+ wrote:
>> SteveW <steve@walker-family.me.uk> wrote:
>>
>>>
>>> We got home from work and found that the guys tasked to turn it back on
>>> had already been down the road and buggered off. Every house where there
>>> was no-one in at the time was left isolated!
>>>
>>> We had to phone and demand that someone came out.
>>
>> I would’ve just turned the gas back on myself unless they’d locked it off
>> somehow.
>
> They left it isolated outside somewhere. I'm sure I could have investigated.
>
>

Your meter cupboard is the only tap between the mains and you house
usually.

Tim

--
Please don't feed the trolls

On 09/11/2022 18:14, Tim+ wrote:
> SteveW <steve@walker-family.me.uk> wrote:
>> On 09/11/2022 17:14, Tim+ wrote:
>>> SteveW <steve@walker-family.me.uk> wrote:
>>>
>>>>
>>>> We got home from work and found that the guys tasked to turn it back on
>>>> had already been down the road and buggered off. Every house where there
>>>> was no-one in at the time was left isolated!
>>>>
>>>> We had to phone and demand that someone came out.
>>>
>>> I would’ve just turned the gas back on myself unless they’d locked it off
>>> somehow.
>>
>> They left it isolated outside somewhere. I'm sure I could have investigated.
>>
>>
>
> Your meter cupboard is the only tap between the mains and you house
> usually.

Our meter is inside the house, as is the lever valve. However, where the
pipe enters the house, it rises from the ground for a couple of feet and
then enters a fitting. The fitting is cylindrical, with a square headed,
screwed plug on the top and an outlet on the back of the cylinder, just
below the top and going through the wall. There may be an isolator in
there, similar to the type for gas fires (remove screw top and then open
or close the valve inside).

As the holes they'd dug were still open at this point, it is also
possible that they'd clamped the yellow plastic pipes closed just after
the gas main, as is done with the blue or black water pipe during repairs.

On Wed, 09 Nov 2022 14:01:57 +0000, Andy Burns wrote:

> David wrote:
>
>
>> I'll wait until everything is on again then run the gas hob for a bit
>> before I turn it back on.
>
> They'll probably visit you to turn it back on.

Yes.
Turned it back on at the outside meter.
Came in to confirm boiler turned back on.
Asked for a hot tap to be run whilst they checked the pressure at the
meter.
All good, and gone.

Cheers

Dave R

--
AMD FX-6300 in GA-990X-Gaming SLI-CF running Windows 7 Pro x64

David wrote:

> Andy Burns wrote:
>
>> They'll probably visit you to turn it back on.
>
> Yes.
> Turned it back on at the outside meter.
> Came in to confirm boiler turned back on.
> Asked for a hot tap to be run whilst they checked the pressure at the
> meter.
> All good, and gone.

Sounds like nobody does the "proper" purging procedure now, per

<http://wiki.diyfaq.org.uk/index.php/Gas_fitting_FAQ#.28iii.29_Purge_the_air_from_the_pipework>

On Thu, 10 Nov 2022 11:35:54 +0000, Andy Burns wrote:

> David wrote:
>
>> Andy Burns wrote:
>>
>>> They'll probably visit you to turn it back on.
>>
>> Yes.
>> Turned it back on at the outside meter.
>> Came in to confirm boiler turned back on.
>> Asked for a hot tap to be run whilst they checked the pressure at the
>> meter.
>> All good, and gone.
>
> Sounds like nobody does the "proper" purging procedure now, per
>
> <http://wiki.diyfaq.org.uk/index.php/
Gas_fitting_FAQ#.28iii.29_Purge_the_air_from_the_pipework>

Probably because modern boilers detect pressure loss and close gas valve?
For a short time when the gas has been turned off at the meter and the
pipework is still full of gas that might be all that is needed.

No idea what they do with old appliances.

Cheers

Dave R

--
AMD FX-6300 in GA-990X-Gaming SLI-CF running Windows 7 Pro x64