Chimney problem

[Karl]

The other day I swept the chimney as I’ve done several times over the years but I’ve also changed the coal and now I’ve got tar running down the side of the roof and even coming down the chimney into the boat. I can see it running down the outside of the chimney in the boat and when it lands on the top of the stove it stinks and has even taken the paint off the top of the stove. I have gone back to the old coal and even though the tar is still coming through it is less. If I burn logs it stops but is more exepensive as I buy kiln dried logs. Why has this started doing this ? Is it just because I changed coal and has more tar in it ? Does it just need burning off in the chimney ?

[tree monkey]

5 minutes ago, Karl said:

The other day I swept the chimney as I’ve done several times over the years but I’ve also changed the coal and now I’ve got tar running down the side of the roof and even coming down the chimney into the boat. I can see it running down the outside of the chimney in the boat and when it lands on the top of the stove it stinks and has even taken the paint off the top of the stove. I have gone back to the old coal and even though the tar is still coming through it is less. If I burn logs it stops but is more exepensive as I buy kiln dried logs. Why has this started doing this ? Is it just because I changed coal and has more tar in it ? Does it just need burning off in the chimney ?

The new coal make be making the issue worse but it isn't the actual issue...

 

The tar dripping down the flue is almost certainly due to a leak in the sealant between the flue and the collar and needs redoing, worst case it may be a hole/corrosion in the flue at the top, allowing tar to drip back into the boat.

 

The tar outside might be more related to the new coal but it's almost inevitable whatever coal is used, best way to mitigate this is a good quality tight fitting double skin chimney 

[Jen-in-Wellies]

Most likely down to the flue to collar sealing going as @tree monkey says. Another possibility is that the flue has actually rusted through within the collar. They have a finite life and coal fumes are very corrosive. The coal type is not the cause.

Jen

[Sea Dog]

When you say "coal", we are talking smokeless solid fuel, right? Cos if you're burning house coal that would be a problem.

[Stilllearning]

On 03/12/2020 at 08:34, Karl said:

The other day I swept the chimney as I’ve done several times over the years but I’ve also changed the coal and now I’ve got tar running down the side of the roof and even coming down the chimney into the boat. I can see it running down the outside of the chimney in the boat and when it lands on the top of the stove it stinks and has even taken the paint off the top of the stove. I have gone back to the old coal and even though the tar is still coming through it is less. If I burn logs it stops but is more exepensive as I buy kiln dried logs. Why has this started doing this ? Is it just because I changed coal and has more tar in it ? Does it just need burning off in the chimney ?

Whatever you do to fix the tar problem, do make sure to remove the tar from the external paintwork as soon as you see it, ideally before it dries. It does stain very efficiently, which I hope you haven’t found out to your cost.