Carbon Monoxide

[HymerVan]

Further to recent threads about Carbon Monoxide and Alarms I have been thinking about the location of the alarm and possible sources of CO.

My van has diesel heating and a compressor fridge. Obviously gas is burned on our hob (we chose to have no oven).

I would not expect the fridge to generate Carbon Monoxide but is there any possibility that the heating could. There is a small exhaust pipe with its own silencer below the van.

 

In edit I haven't put this question very well. I appreciate that the exhaust emissions from the heater will contain Carbon Monoxide and that in theory at least these could find their way into the van.

Perhaps this suggests that the CO alarm should be at a lower level.

[Derek Uzzell]

Your diesel-fuelled heater's exhaust should have been positioned so that the chances of exhaust gasses entering the vehicle are nil. If you can (realistically) envisage those gasses getting in, the exhaust should be repositioned.

 

Where's the heater located on a Fifer? Though, wherever it is - inside or outside the vehicle - I'd still put the CO alarm midway between floor and ceiling.

[HymerVan]

Thanks Derek

The heater is partially within and partially underneath the vehicle located in the seat locker about half way along the rear (non cab area) The exhaust pipe (which looks like braided stainless steel hose) dangles underneath on the offside with the pipe terminating just beyond the edge of the vehicle i.e. it just clears the vehicle. Consequently the risk of gases building up underneath and seeping into a stationary vehicle seems slight. The alarm is at about 4ft height (pretty close to half way and about 18 inches above where your head would be if you were sleeping.

[terryW]

Better positioned than the Globecar Trendscout we had. The exhaust outlet fro the Combi boiler was directly below the one window we liked to keep open for air.

 

Trendscout owners please take note if you haven't already seen the danger. :-(

 

Sorry for the deviation on your thread.

[Brian Kirby]

That seems to go against Truma's installation guidance which, I seem to remember, said that if the flue was below a window a cut-off switch should be installed on the window, to switch off the heater when the window was open.

 

To the OP, I would just say carbon monoxide (CO) is a product of poor combustion, usually caused by insufficient oxygen.

 

Heaters almost invariably have fan fed balanced flues with two fans running in tandem so that both combustion air supply, and exhaust, are force-vented. If the fan fails, the heater will not run. For those heaters that need servicing, and I believe the diesel ones do, soot deposits inside the combustion chamber can also result in significant CO emissions. For these, servicing at the recommended intervals is essential to maintaining safe operation. Besides all of which, the flue gases will be smelly, so difficult to ignore.

 

A compressor fridge involves no combustion, so cannot generate CO.

 

Your hob would only generate CO if used without ventilation, which is why vans have permanent ventilation provision, often via un-sealed rooflights. If in doubt, open a window when using the hob etc.

 

To be honest, if your van has the requisite permanent ventilation, which I'm sure it will have, the risk of CO poisoning is so low I think the alarm is completely redundant. It is not there as a result of a risk assessment, it is there to comply with a non-mandatory construction standard that did not foresee an arrangement such as you have. But, make of that what you will! :-)

[WildBill]

Carbon Monoxide is produced by poor combustion in any fossil fuel burning appliance. Poor combustion may occur in an appliance if it is badly fitted, poorly maintained, has blocked flues, or insuffcient ventilation. It is odourless and slightly lighter than air.

Most heating appliances in motorhomes are room sealed and if regular servicing and safety checks of the appliance are carried out, the risks of CO entering the motorhome from that appliance are minimal. However, there always remains a risk.

I am a Gas Safe registered installer and know the signs of CO. I make sure that my appliances are in good condition. I also have a CO alarm fitted.

The cost of a CO alarm is minimal compared to the cost a life, so I can not see why anyone would think that they do not need one. B-)

[747]

With regard to boilers with balanced flues (like my Alde 3000), there is a potential hazard with these flues.

 

My boiler developed a fault on the ignition circuit and I ordered the parts. To fit them, it meant removing the flue which is a plastic outer and Aluminium inner. When I loosened the Jubilee clips, both ends of the Alu (which exhausts the hot product of combustion) was damaged at both ends and not sealing properly. This Alde boiler is fitted in an internal cupboard at floor level. If the outer hose was not airtight then CO could have entered the van. It also meant that my boiler was not operating efficiently and this is what produces CO.

 

If you have the Alde boiler, this is worth checking. I believe the problem arose because Burstner shoe-horned the boiler into a small space resulting in the flue being bent through 180 degrees with too tight a bend.

[colin]

To answer the OP, the height of your CO alarm is IMO just fine, whilst CO might enter at a lower level it will most likely rise to upper level in van, it is very unlikely that CO will gradually fill up from lower level to lethal levels without first setting off alarm.

[HymerVan]

Thanks for these helpful contributions. I feel more comfortable now.

In my part life part of my training included a degree course in forensic medicine so I am well aware of the dangers even in small concentrations of "the silent killer"