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Hot ash setting of the carbon monoxide detector?


Simon2021

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I'm new to narrowboat life, having moved onboard in April of this year. And I've only been using my multi-fuel stove (which was installed brand new recently) for a couple of weeks. Today, I topped up the stove with coal (Supertherm smokeless coal) at around 8am and then at 10:30am the carbon monoxide alarm went off.

 

I opened all the windows and doors and kept them open for an hour. I also replaced the old detector with a new one that did not go off. After an hour, I closed the windows and for about two hours everything seemed fine and the new alarm didn't go off. Then the new alarm went off. It has a voice alarm that says "Carbon monoxide detected!". So I opened all the windows and doors again.

 

At no point did I feel ill or have a headache etc.

 

Once the windows were opened the alarm went silent.

 

I started looking for a cause. The stove was still smouldering, the door closed and vents shut. And I checked the batteries in the engine bay and the LPG gas. Then I thought to look at the ash can.

 

Our 'ash can' is actually just a metal bucket with no lid. When I poked around with the tongs I was shocked to see a great deal of red glowing embers. There was a lot of warmth coming of the can (but not too hot, the side of the can was warm but not hot).

 

The only difference between today and other days that the stove has been lit is that this morning there was a lot of ash in the stove (we burnt for the first time an ecoblaze log) which I emptied into the bucket. I see now that there must have been a lot of glowing embers I didn't see.

 

For the experienced (and not as foolish as me) it is common for ash to set of the carbon monoxide detectors?

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Yes. This is a known problem with hot ashes from the stove, which can smoulder away slowly producing CO. CO produced in the stove will go up the flue, not so if the embers are in a bucket in the cabin.  Always store your ash outside the cabin, and not in a well deck where the CO could find its way back in through the low level vents in the front doors or bulkhead.

Edited by David Mack
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1 minute ago, Simon2021 said:

 

 

For the experienced (and not as foolish as me) it is common for ash to set of the carbon monoxide detectors?

 

 

YES.

Ash should only be stored outside, and preferably bankside. Storing it in the cratch / well deck allows it to re-enter the boat, and you will 'wake up dead'.

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I set off my CO alarms once by leaving the ash bucket on the OUTSIDE stern deck step. Unbeknownst to me, despite the grey ash on the top, the ash beneath was getting very hot and glowing orange. It was enough to spew out carbon monoxide that came in through the vents in the stern doors and that set off the alarms.

 

Ash gets taken outside, well away from the doors, now. And when cooled, dumped into a larger bucket on the deck to be disposed of later. 

 

Please be mindful not to leave buckets of ash on the bank if near to the towpath. Passers-by, especially after dark or if skirting round puddles, branches or around other towpath users, might trip over it creating not just the risk of fall-injuries but potential burn injuries too. 

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As I understand it CO is the result of incomplete combustion. Combustion occurring with some, but not enough, oxygen. 

 

Consequently the mistake is having the hot ash in an open bucket. Put a closely fitting lid on and the supply of oxygen will all but stop and combustion will cease, along with the CO.

 

In theory anyway! 

 

 

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35 minutes ago, MtB said:

As I understand it CO is the result of incomplete combustion. Combustion occurring with some, but not enough, oxygen. 

 

Consequently the mistake is having the hot ash in an open bucket. Put a closely fitting lid on and the supply of oxygen will all but stop and combustion will cease, along with the CO.

 

In theory anyway! 

 

 

Well yes, but still NEVER keep ash inside the cabin. It really does kill people.

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22 minutes ago, nicknorman said:

Well yes, but still NEVER keep ash inside the cabin. It really does kill people.

 

Why would anyone keep hot (or cold) ash inside the boat? I don't really get it. 

 

Ok I see the advantage of not carrying hot ash outside in case it gets spilled or dropped and causes injury or a fire, but I've been carrying it out for 20 odd years and I'm just very careful.

 

On the other hand, in terms of spillage, emptying hot ash into a bucket inside the boat seems quite dangerous too so I don't think there is any benefit.

Edited by blackrose
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2 hours ago, nicknorman said:

Well yes, but still NEVER keep ash inside the cabin. It really does kill people.

 

Yep, i should have said so. 

 

I should also have pointed out that rather than a bucket (with lid or not), a "Tommy Tippy" ash container is the thing to use to minimise CO risk. Or one of the many clones around nowadays.

 

With these, you can put the whole ash pan inside it filled with the ash, close the lid and carry the whole lot outside. Open the lid outside and get the pan out leaving the ash inside. much cleaner than tipping ash into a bucket inside the boat. Then leave the container containing the ash outside with the lid closed to cool and dispose of later once cold. that's how I use mine anyway.

 

image.png.b5a800efd5d3342ef7ea55127eb64f4a.png

 

 

https://www.ebay.co.uk/itm/265313196429?epid=1374579566&hash=item3dc5e6198d:g:oKIAAOSwvVxhQMah

Edited by MtB
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We had the same trouble with our CO2 alarm going off till we got one of these https://www.onbuy.com/gb/valiant-fireside-tidy-ash-transporter-black-gloss-steel-storage-box-fir240~c13671~p7482999/?exta=gshp&stat=eyJpcCI6IjI5Ljk5MDAiLCJkcCI6bnVsbCwibGlkIjo3NjA3ODY1MiwicyI6bnVsbCwidCI6MTYzODc0NzYzMSwiYm1jIjoiMTAuMCJ9&lid=76078652&gclid=CjwKCAiAhreNBhAYEiwAFGGKPHvVfXCb9vQ6jdIu3DObVNqbZ-yIXeoBXxoOI-zpxj1Agmlr9UByYRoCulMQAvD_BwE

Not had any trouble since. 

I would also say to check you alarms and fire extinguishers at least once a month. With the fire extinguishers, take them off of their mounting and turn them upside down a few time to shake up the powder inside. 

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And one other thing from someone who has had a dose of CO poisoning - trust your CO alarm and don't wonder it it might be faulty if it goes off. They simply don't go off if there isn't any CO around. CO is colourless, odourless and tasteless, so you can't detect it yourself.  

 

Edited by Tom Morgan
To correct a spelling mistake.
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Our CO alarm has a digital display which is hopefully always on zero. But recently it started to show 10, 15, maybe 20 ppm for a long time after the stove had been refuelled. Not enough to activate the alarm, but not comforting! We’d had this problem before, flue partially blocked. And anyway I’d noticed it wasn’t lighting and drawing very well. But really difficult to clear out properly because it has a bend near the top.

 

So last week I finally bit the bullet and completely removed the cast iron flue. Which wasn’t particularly easy! Wedged really tightly into the roof collar with masses of glass rope, so I had to use a drill between collar and flue. It must have taken a couple of hours to get all the glass rope out.

 

As expected, the lower portion was severely congested with concrete-like stuff. Probably 1/2 the diameter was lost which (if my mental arithmetic is correct) means 3/4 of the area was lost. It required a hammer and chisel to dislodge, and when that ran out of reach, a mooring stake and mooring hammer. Fortunately just as the stake ran to the limit of its reach, the last lumps fell out. Weirdly there was a step change where it just stopped, about 1/3rd of the way up.
Several kilos of “concrete”removed. Flue replaced with lots of glass rope and Envirograf 1200 degC silicone. Hopefully we can now add fuel to the stove without gassing ourselves!

 

I don’t know if there is a way to stop that build up again, otherwise I’ll have to repeat  the process in another 10 years!

Edited by nicknorman
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19 minutes ago, nicknorman said:

Our CO alarm has a digital display which is hopefully always on zero. But recently it started to show 10, 15, maybe 20 ppm for a long time after the stove had been refuelled. Not enough to activate the alarm, but not comforting! We’d had this problem before, flue partially blocked. And anyway I’d noticed it wasn’t lighting and drawing very well. But really difficult to clear out properly because it has a bend near the top.

 

So last week I finally bit the bullet and completely removed the cast iron flue. Which wasn’t particularly easy! Wedged really tightly into the roof collar with masses of glass rope, so I had to use a drill between collar and flue. It must have taken a couple of hours to get all the glass rope out.

 

As expected, the lower portion was severely congested with concrete-like stuff. Probably 1/2 the diameter was lost which (if my mental arithmetic is correct) means 3/4 of the area was lost. It required a hammer and chisel to dislodge, and when that ran out of reach, a mooring stake and mooring hammer. Fortunately just as the stake ran to the limit of its reach, the last lumps fell out. Weirdly there was a step change where it just stopped, about 1/3rd of the way up.
Several kilos of “concrete”removed. Flue replaced with lots of glass rope and Envirograf 1200 degC silicone. Hopefully we can now add fuel to the stove without gassing ourselves!

 

I don’t know if there is a way to stop that build up again, otherwise I’ll have to repeat  the process in another 10 years!

A length of 28mm blue water pipe, flexible enough to go round bends, with lots of 4" stainless screws driven through near one end will rat out the crud. Be sure to clear the top of the back boiler on the Squirrel, the flue throat is small and it blocks easily. And it will set solid again if it builds up there.

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42 minutes ago, Tom Morgan said:

And one other thing from someone who has had a dose of CO poisoning - trust your CO alarm and don't wonder it it might be faulty if it goes off. They simply don't go off if there isn't any CO around. CO is colourless, odourless and tasteless, so you can't detect it yourself.  

 

 

Also remember (fortunately) that it is NOT ONLY CO that sets off the CO alarm.

 

Middle of the night CO alarm goes off, hunt around the boat, nothing on, no fire, no gas burners - nothing.

Open windows and wave a towel about until the alarm stops so decide it must just be an alarm fault.

 

About an hour later (fast asleep) and the alarm goes off again. repeat waving the towel about until it stops.

Decide to have a look in the engine room, remove the steps that give entry under the floor and crawl into the walkway.

Eyes start to burn, throat gets sore (no smells - just 'taste')

Track the source down to one of the (six) 230Ah batteries (big thing weighs 55kgs) that is looking like a rugby ball with the ends distended. The battery is BOILING hot and I cannot even touch that terminals.

Got the spanners and disconnected the battery from the bank.

 

Heat unbearable, fumes choking.

 

Switched on the Engine room blowers, opened all doors and windows and waved the towel about again.

 

Eventually got back to bed for a couple of hours sleep.

All the following day the battery was too hot to handle and I was a bit concerned about it surviving being dragged and lifted out of the engine room.

Eventually it cooled down enough to get it out.

 

I reckon we were only 'seconds' away from a catastrophic battery explosion and saved only by the CO alarm sensing the fumes generated by the battery having an internal short.

Edited by Alan de Enfield
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13 minutes ago, Tracy D'arth said:

A length of 28mm blue water pipe, flexible enough to go round bends, with lots of 4" stainless screws driven through near one end will rat out the crud. Be sure to clear the top of the back boiler on the Squirrel, the flue throat is small and it blocks easily. And it will set solid again if it builds up there.


That sounds like a great idea, thanks.

 

We don’t have a back boiler on our Squirrel but of course the throat plate needs regular cleaning anyway.

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We had a straight flue and regularly would clean it using a bi-metal holesaw on the end of a length of pipe, effective in removing hard deposit build up, especially just above the stove collar. Also I used to give the thick walled flue a good hammering  just before we lit the stove in the autumn (by then a coat of rust had loosened any scale) a fair amount of hard scale fell down. 

FWIW we kept ash in a Tippyash next to the stove and never had any detectable CO. 

Edited by nb Innisfree
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1 hour ago, nicknorman said:


That sounds like a great idea, thanks.

 

We don’t have a back boiler on our Squirrel but of course the throat plate needs regular cleaning anyway.

 

I eventually stopped putting it back in my Squirrel after cleaning the crud off it each time the stove performance degraded.

 

No discernible change in stove performance, heat output, fuel consumption or anything else (apart from no more accumulation of crud on the throat plate that wasn't there). 

 

 

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1 hour ago, nicknorman said:


That sounds like a great idea, thanks.

 

We don’t have a back boiler on our Squirrel but of course the throat plate needs regular cleaning anyway.

 

Our flue at home gets a good raking out annually with a tool our sweep uses that looks like a flower with metal petals that spin on a rapidly rotating shaft.

 

It sounds brutal but works.

 

But its done annually, surely boaters should be doing the same or similar with their's.

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