Intermittent CO issue

[mikehiow]

Hi, I am neither a plumber or a gas engineer, but hope to call on your collective experiences in the hope someone may have experienced this issue or have any ideas as to the cause.

Sunday night my Carbon Monoxide alarm went off, I quickly shut the boiler and gas off and opened all the windows. The firm that installed the boiler came out Tuesday morning and could not find any fault nor any sign of a carbon monoxide leak.

To rule out the alarm being faulty, I purchased a new alarm, this time a different model with a digital display and functionality to display peak levels.

The morning after "installing" the new monitor, I noticed the peak was at 35ppm but dismissed it as being a quick snap or a mis-read as the alarm did not go off.

Moving forward to today, I popped out for a few hours, the house was empty and upon my return the alarm is going off. My neighbour informs me that it was going off for a good hour.

Again, I turn the boiler, shut of the gas supply at the meter and call the gas engineer again. The CO meter is reading 96ppm, with a peak of 100 (I assume it tops out at 100, as it seems too round to be an actual reading), I reset it just in case (After opening all of the windows) and place it back inside, it's now reading 46ppm and falling as air circulates through the house.

A short time later, the engineer turns up, checks the ratio in the flue and tells me its a rather healthy 6.5. He stays for a further hour to check around various other places with the boiler running and comes up empty, with a maximum reading of 2ppm above the boiler and 3ppm below the worksurface under the boiler, oddly. Further investigation revealed nothing.

The only other source of gas or in fact any fossil fuel burning in the house is the gas hobs, which had not been used any time near either "event". Next door have since armed themselves with a couple of CO alarms, too. No one smokes inside the house - I am a smoker, but was out both times.

The boiler is a Worcester Greenstar 15 Ri, which I believe is a condensing unit (it has a water outlet) and was fitted roughly two years ago.

FWIW, all windows were shut at the time.

Any help or suggestions would be greatly appreciated, I do not intend on attempting a repair myself obviously, but if I could replicate the issue then I'd be one step closer to getting it fixed.

Thanks in advance,
Mike.

 

[GQuigley67]

is it an open flued boiler ? it could be a ventilation problem, is the vent blocked ?

 

[mikehiow]

I believe it's what you call a balanced flue? ie. the outlet runs inside the inlet.

 

[Billy Bob Bob]

Worcester Greenstar 15 Ri, y7ou probably did not see this bit gq,lol i do that alot,so we know its a condensing room sealed boiler,6.5% co2 on the fga reding is well in but do you have a horizontal or vertical flue mike?

 

[mfgs]

A 15Ri is roomsealed. If he was getting any rise in CO level around the boiler whilst operational, compared to a reading from the room when the appliance is off then the gas supply should be capped to the boiler until the problem has been rectified. 100ppm of CO is deadly.


DO NOT USE THE BOILER UNTIL CHECKED OUT PROPERLY.

 

[Billy Bob Bob]

yes its both never seen one fitted like that thats not to mi,s surely

 

[mfgs]

Ive never seen a plume kit used like that before, looking at the picture it looks as if there will be some joints on that plume kit, perhaps they have become dislodged?

 

[Billy Bob Bob]

Ive never seen a plume kit used like that before, looking at the picture it looks as if there will be some joints on that plume kit, perhaps they have become dislodged?

me neither it looks highly suspicious and contravenes the regs as the flues enclosed in the roof space and the air intakes to close to the fascia

 

[GQuigley67]

must be something to do with the flue, can you get access to it ?

lol didnt realise that part, its a long OP

 

[mfgs]

me neither it looks highly suspicious and contravenes the regs as the flues enclosed in the roof space and the air intakes to close to the fascia

Yeah, very odd. I dont know why anyone would think that it was acceptable to do that.

 

[Billy Bob Bob]

to the op useing it strait away call in another gas safe registered engineer the flue set up you have there looks far from right and is probably slowly killing you and your family

 

[mikehiow]

Boiler has been shut off, I will get another gas engineer round to check it out. It is very worrying, as we have a 6 month old daughter, although I had already sent her and the OH to her Mum's just to be safe.

Thank you for your help, I'll be sure to update here with any progress.

 

[capitanpugwash]

Mike

Is the flue area where it disappears into the soffit accessible from inside to inspect the flue or is it inaccessible as it looks? Was the vertical section of the flue there before- has it been joined on to with the new boiler, or was it all new at the same time?

 

[mikehiow]

It is not accessible from inside, I suspect the soffit will have to come out to have a look.

The boiler was installed before I moved in, however looking at the installation I'd say it was all new. In fact, if I remember rightly, I've got a feeling I was told there was a very old cylinder burner here before the boiler was installed.

I suspect they went up and hit a beam directly above where it comes out of the wall, hence what I assume is the S bend inside the soffit and the upper outlet not lining up with the pipe coming out of the wall.

 

[capitanpugwash]

Would there be any problem with putting a new straight flue through the wall and effectively capping off the existing flue which looks like it has too many bends and connections in it? If it is leaking through any of these then you may be best off simplifying it so it is inspectable for the length of the flue. I would also want first to open up the soffit to try and find the leak. If you find a suspect connection then that could be your answer. Well done for recognising the danger, turning off the boiler and sending away your family. This situation could have ended up in tragedy...