Carbon Monoxide Alarm Question

sho_me_da_money

Wife was cooking today and it was a pretty smokey kitchen.

After turning off the gas appliance, we were in the living room when for the first time ever the Carbon Monoxide alarm went off.

I brought the alarm into the main living area and it went off after say 5 mins.

Took it back into the kitchen and it went off again.

Called the emergency line and opened up all the windows until they sent out a technician.

When the guy came, he had a tool and said the Gas Cooker is emitting 4PPM but may likely have been higher earlier. He turned off the gas supply to the house.

Called a gas safety registered person out who charged £90.00 and could not replicate the issue or readings on the boiler or the gas cooker. On his detector, he held the needle close to the hob and the CO rating went to 50+ but he said this was normal. He then hovered this at a height above the hob and it dropped down under 5.

In the end he left the gas on and said open the windows when cooking.

The CO detector was one supplied by British Gas. It was not faulty and was valid til 2027.

How do I avoid such false alarms in the future that just cost me nearly 100 quid which i cannot afford?

Could it have been the smokey kitchen at the time?

DullGreyGuy

sho_me_da_money said:

When the guy came, he had a tool and said the Gas Cooker is emitting 4PPM but may likely have been higher earlier. He turned off the gas supply to the house.

Called a gas safety registered person out who charged £90.00 and could not replicate the issue or readings on the boiler or the gas cooker. On his detector, he held the needle close to the hob and the CO rating went to 50+ but he said this was normal. He then hovered this at a height above the hob and it dropped down under 5.

So the two people agree, one registered less than 5ppm and the other registered 4ppm which is less than 5. 

What colour is the flame on a long cook? Should be blue, if you are seeing yellow/orange then it's lacking oxygen when burning and that produces CO. Similarly look at the bottom of pans after cooking, if they have black/brown marks then it's again likely soot which shouldn't exist on a clean burning supply. 

How long was the gas safe person running the burner? Was it with the same pan on top of it or naked flame? 

Both readings are low but ultimately could build up without ventilation. Ultimately not a bad suggestion of opening a window when doing anything more than a quick cook. 

FreeBear

sho_me_da_money said: The CO detector was one supplied by British Gas. It was not faulty and was valid til 2027.

Might pay to get a replacement CO alarm now - They have a limited life span, and can be purchased fairly cheaply (under £20 for a basic model).

sho_me_da_money

Thanks for both responses. To answer the questions:

- Flame was blue and not lofty
- Second engineer who came out and charged me left the burners on without any pan so naked flame. It could be the pan to be honest as we were making chapattis and using like a flat tawa that we bought from Amazon a few weeks back. No idea.

The second engineer held the meter steadily from a distance above each cooker hob and although the meter went to around 4, it wasn't stable. It started retracing down to 1-2.

Im just a bit gutted I had to pay 100 quid to learn that i should open windows.

sho_me_da_money

Im convinced it may be this pan. No alarm gone off in the past 2 weeks when cooking with this but given that it has clear rings under the pan and the 'black' paint is gone, could it be this?

BarelySentientAI

There was never black paint on the bottom of that pan to begin with.

MattMattMattUK

In theory a large wide pan can inhibit complete combustion and cause CO to be produced because the wider the pan the lower the airflow. In general this would not cause any health issues but if done over an extended period of time it could cause it to reach the warning threshold of the alarm which is quite a bit lower lower than the level that presents any health/safety issues. Do you have an externally venting extractor fan? If so they are always advisable to use when using any hob, but especially a gas hob. 

DullGreyGuy

sho_me_da_money said:

Im convinced it may be this pan. No alarm gone off in the past 2 weeks when cooking with this but given that it has clear rings under the pan and the 'black' paint is gone, could it be this?

That is how it will have been manufactured. 

If you put a very wide pan on a small ring it naturally reduces the amount of air that can get to the flame which increases the chances of the gas being converted to CO rather than CO2. We have a 32" flat disc of cast iron which is a traditional cooking surface for some unleavened bread and the old gas hob was not happy if you tried to use it on one of the smaller burners. 

In most cases these will still be relatively low levels but always best to have an open window or use an externally venting extractor fan to prevent buildup over time. We switched from gas to induction and now much better for using a plancha type surface. 

sho_me_da_money

BarelySentientAI said:

There was never black paint on the bottom of that pan to begin with.

Sorry not following. What is the black on the underside that is eroding and showing the silver 

BarelySentientAI

sho_me_da_money said:

BarelySentientAI said:

There was never black paint on the bottom of that pan to begin with.

Sorry not following. What is the black on the underside that is eroding and showing the silver 

The "clear rings under the pan and the black has gone" were never black.  Those rings were always silver ('clear').

I see a few scratches to the black elsewhere on the bottom, but that isn't erosion and has nothing to do with heat.

Or are you talking about something else entirely?

edit:  I now think I've interpreted the photograph completely wrong and this post is incorrect.

mmmmikey

It looks to me like a wide outer ring of paint on the curved section of the pan between the machined base and the rim has burnt off (between the 7 o'clock and midnight positions on the photo).

It is quite possible (I think?) that the smoke from the burning paint would have smothered the burning gas to some extent, starving it of oxygen and leading to a build up of carbon monoxide. I'm only speculating here but it seems like a reasonable explanation?