CO detector for boiler required / recommended?

[Caecilius]

I've been told by the "heating engineer" who serviced my boiler that a carbon monoxide alarm is "required" - it's a non condensing ideal standard system boiler with a balanced flue.

I've never had this recommendation for a room-sealed appliance before, so I asked why and was told that:

"it's an old boiler with a fan assisted flue, which means it works under pressure. If it is ever under positive pressure and the seal was to break on the boiler, it would release harmful products of combustion into the house which could kill you".

Is this really true, or am I being spun a line? The flue gas readings were fine, and the flame appears blue through the inspection window.

My thought is that roomsealed appliances are fairly safe, and it would require several faults to occur (seal fails, positive pressure, bad mixture setting).

Does anyone have any thoughts on this? I thought CO detectors were mainly required for solid fuel and open gas fires.

[Theo]

Spend a tenner and get a CO detector? Irrespective of the letter of the law it seems a cheap safety measure where a combustion appliance is present.

Theo

[Max Demian]

I was told that every room with a gas appliance needs a CO detector; perhaps this only applies to rented property in the way that the landlord has to have gas appliances checked once a year.

[Owain Lastname]

Required by law in Scotland from 2022 in all homes.

Owain

[ARW]

I have not got time to double check but ISTR gas cookers were excuded.

It will be under Part P of the building regs.

However this applies only to landlords or retrosectively if a house owner has work done. I am not sure if having a boiler swapped would require you to have one fitted.

[Steve Walker]

While it is a good idea, making building regulations retrospective and forcing people to make changes to meet them is not. How long before homeowners are told, regardless of cost and their circumstances at the time, to make other changes - insulation, double glazing, heat pumps. etc.?

Anyway, in most houses, normal (non-sealed, non-interlinked) alarms are good enough to wake the occupiers.

As for having a detector in "the most used room" - yes, great for smokers, but of little benefit for anyone else.

[Brian Gaff (Sofa]

Personally if I had any gas or oil burning device, I'd fit one. I often wonder where would be the best place though. does co2 go up or down? Brian

[Brian Gaff (Sofa]

Many of the more expensive ones can do other gasses as well, I understand. Not sure how these work. CO and Co2 are pretty easy, but if they are meant for combustible gas leaks, then how do they work? Brian

[John Walliker]

The cheap ones have a small bead of porous catalyst on a support consisting of two parallel fine resistance wires with the bead straddling them. A current is passed through one of the wires to heat it up. The catalyst then facilitates oxidation of the fuel gas, causing the bead to get hotter which is detected by a change in the resistance of the other wire. To save power, the device is only turned on for a few seconds every few minutes. The sensor is enclosed inside a wire mesh capsule to contain any flame or explosion that might be triggered by its operation.

John

[Martin Brown]

It is a very good idea to have one. The flame will still be a good blue and burning quite happily long after it has killed you by carbon monoxide poisoning. Humans and CO are a very bad combination you should have a CO detector if you have any sort of combustion based heating.

They are inexpensive and a useful protection against an avoidable risk.

Anything involving combustion that might one day spring a leak. It doesn't take much of a leak of CO into your home to be deadly. I have seen an oil boiler fail this way and leak exhaust gasses hot enough to char wood - fortunately it self limited by melting its mains cable.

Various countries with dodgier safety standards kill a few British holiday makers every year (or did when overseas travel was allowed) through failure to have CO monitors and poorly serviced gas heaters.

[Max Demian]

"If you have a carbon-fuelled appliance ? like a boiler, fire, heater or flue ? in any room, you must also have a carbon monoxide detector in that room, but this does not need to be linked to the fire alarms."

So it's not just gas appliances. Presumable it would include candles used during a power cut, or to make the room smelly.

The Scots do like their regulations. This is what comes of allowing people to govern themselves.

"We'll have rules ... Lots of rules! Then when anyone breaks 'em - ..."

We know what happens in the end (Lord of the Flies).

[Owain Lastname]

Not just abroad.

The owners of a holiday cottage where a teenager died from carbon monoxide poisoning in 2015 have been fined.

Thomas Hill, 18, was found unconscious behind a bathroom door at Glenmark Cottage, near Tarfside, in Angus, where faulty gas heaters were found. Burghill Farms and Piers Le Cheminant, who ran the cottage, admitted exposing holidaymakers to the risk of death. Burghill Farms was fined £120,000 and Le Cheminant, 76, was fined £2,000 at Dundee Sheriff Court.

A subsequent investigation revealed that there had been cracks in the heater and it was found to be producing carbon monoxide greatly in excess of safe levels. Burghill Farms and Le Cheminant both admitted that between March 2008 and October 2015 they failed to ensure gas cabinet heaters were maintained in a safe condition to prevent the risk of injury to holiday residents. They admitted the heaters were being used in rooms which were too small and not ventilated enough.

Mr Callaghan said the heater "should never have been in the bathroom." He said: "A competent gas engineer would have identified the risk. Neither Burghill Farms nor Mr Le Cheminant had a pro-active system of maintenance.

Owain

[Steve Walker]

What risk with a fan flued, room-sealed boiler though? Due to the exhaust fan keeping the whole enclosure under slightly negative pressure, any casing leak can only be INWARD, not out into the room. That the fan is doing its job is confirmed by pressure switches, that will not allow the burner to be supplied with gas, unless the fan is functioning.

Even a leak in the exhaust itself is no problem, as it is run co-axially in the centre of the air inlet, so any escaping fumes will simply be sucked back though the burner section and out of the exhaust again.

Older boilers can be open to the room; sealed but un-fanned; or with an inlet fan, so the casing pressure can be positive - but they all fell out of favour decades ago.

[Fredxx]

<snip>

Smokers inhale a significant amount of CO.

On the matter of a blue flame, can you cite any source for this claim. The conventional view is that a blue flame, ie no yellow, creates a zero or an minimal amount of CO.

On that I do agree.

[Tim+]

Pretty sure my present and my last boilers have had their fans on the inlet, not the exhaust and hence are at positive pressure.

Tim

[David]

<snip>

Consensus so far seems to be that it is not required but is generally advised.

I don't recall this being a big issue around 10 years ago, though.

Cheers

Dave R

[Robin]

I find such arguments more persuasive if supported by /quantified/ costs and benefits - even if those involve sometimes heroic estimates. Regulations from a Whitehall department would routinely have them in the impact assessment (as e.g. with the requirement for landlords to fit alarms). The Scots didn't publish them when they requires CO plus interlinked smoke/heat alarms and couldn't answer questions about them later. But I suppose we can at least give them credit for remembering DIY: they assumed people can DIY the fitting of 3 smoke + 1 heat /interlinked/ alarms + 1 CO alarm for £220. Seemed to me a tight budget. And to beg the question "what about the people who can't DIY?"

[Fredxx]

Prior to condensing boilers that was the norm.

The most recent boilers I have seen have a fan just prior to the burner; where the gas enters and is mixed between the fan and burner. A modulating boiler will change fan speed in sympathy with gas rate. The casing is in negative pressure.

Having the case under negative pressure is certainly the safer option.

[Fredxx]

There seems an anti-gas sentiment surrounding gas and over-reaching concern over gas safety.

People ought to be more concerned over crossing the road if safety is their foremost concern.

[Tim+]

Both these boilers were/are condensing.

Now I?m confused. You said they were on the exhaust. ?Prior to the burner? and ?exhaust fan? would seem to be mutually exclusive.

Hm, with a fan prior to the burner I?m not sure where your negative pressures are coming from.

Tim