Tar deposits in damp chimney

jezko

Would Insulating a new flue liner reduce exterme Tar deposits in a "Damp" Chimney?

Multi Fuel Stove is attached to Chimney via a Metal Pipe going about 2 Metres into Chimney on a External Wall.

Been told Need to Re line with a Flexi Metal Flue but no Mention of Insulation....

demanufactured

Bad installation you have there.
Ya cant just shove the flue pipe from the stove up the chimney.
It needs to be sealed.
You need a shorter length of flue and a reducer to connect it to the clay flue.
You probably burn damp timber or turf and have the air.control turned down when the fire is lit?

You could go the expensive route and get flexible double walled liner but it will cost a fair bit and if.your clay flue is in good condition you shouldnt need it.

jezko

Bad installation you have there.
Ya cant just shove the flue pipe from the stove up the chimney.
It needs to be sealed.

I have found this out thanks Bought the house with this installed
We discovered the tar deposits when the Chimney was swept (Inside the clay Flue) and discovered the clay flue is badly cracked and needs to be removed and replaced


and have the air.control turned down when the fire is lit?

Not quite sure what you mean here.. Once the Fire is going I close the Air intakes to the stove and allow the Fuel to Smolder...

You could go the expensive route and get flexible double walled liner but it will cost a fair bit

Any Ideas what this would cost?

Thanks

gsxr1

you need an expert to check your set up.

Your problem has the potential to be dangerous.

demanufactured

What fuel do you burn

jezko

gsxr1 wrote: »

you need an expert to check your set up.

Your problem has the potential to be dangerous.

Thanks, I Know, I have contacted a Company the specializes in Chimneys....

Just Want a idea of what could be done .. How much ...Pro ...con etc... If need to go Whole HOG and insulate a 1980's build External wall Chimney

jezko

demanufactured wrote: »

What fuel do you burn

Some coal to start off and Mix of seasoned Soft wood...(Mostly Alder...some Ash, Acer etc.... Been under cover a Year and more.

Been in the House since End August and stove lit once in a while since... Not Much Material (Mostly Soot in Stove flue...) But on top of Chimney is Very Damp Tar deposits...
Had it cleaned mainly due to terrible Down Draft ... and have been told Flue is Cracked in top and below the point where stove flue entres clay... ( Haven't lit this Fire for weeks now due to downdraft) Don't worry it won't be lit now till new/repaired Flue...

heinbloed

and have the air.control turned down when the fire is lit?

Not quite sure what you mean here.. Once the Fire is going I close the Air intakes to the stove and allow the Fuel to Smolder...

Well, that is exactly how tar is produced. Uncompletely burned gases hitting a cold surface. Condensation. Tar.

The flue gas temperature should be well above 300 degrees Celsius at the outlet of the chimney, depending on the type of solid fuel.

The way the OP is using his fire must lead to trouble, to deposits in the chimney.

B.t.w.: it doesn't matter how many bends or meters of stove pipe are installed, how long the chimney is: as long as the flue gas ( the 'smoke') is not cooled down to much condensation can't happen.
Therefore the outlet temperature of the chimney is decisive. If tar is found in the chimney or stove pipe than the fire is not maintained efficient and save.

If the OP insists on the modus operandi as used to then a flue-gas heatexchanger should be installed between combustion (stove, boiler) and flue gas pipe (stove pipe).
This "flue gas heatexchanger" (google for this term) is designed to cool down the flue gases, making maximum use of the created thermal energy. But the chimney itself must then be capeable to take condensed water.
And this heatexchanger must be inspected and cleaned on a regular base.

If the flue gas system is technically not designed to cater for low temperatures then the fire must be run hot. Not smouldering!

heinbloed

The down draft is not caused by a cracked chimney liner.
It is caused by a pressure differential.

So a new chimney liner won't help against an existing down draft.
A chimney cowl might be the first choice to try, but maybe the chimney itself is simply to short and the down draft caused by turbulences of the air.

Storing fresh logged timber for only 1 year in the Irish damp climate is not enough. 3 years is more likely to be the minimum to achieve a residual moisture of <18%.
After drying the timber outside bring it inside and store it there for another while. In a heated and ventilated environment. The place next to the stove (minimum distance!)would be perfect - if the stove's combustion is suplied with the air coming from the room itself to guarantee ventilation.

jezko

heinbloed wrote: »

The down draft is not caused by a cracked chimney liner.
It is caused by a pressure differential.

So a new chimney liner won't help against an existing down draft.
A chimney cowl might be the first choice to try, but maybe the chimney itself is simply to short and the down draft caused by turbulences of the air.

.

True, the crack is not causing the down draft I had planned to Fit a "H" cowl and extend to chimney flue another 2 foot...but before this wanted to clean the chinmey .

But I was told the state of a flue could be the cause ... if in the middle of the flue a object was partial blocking the air flow etc