Smoking fireplace

[wessex101]

Another thing to take into consideration is air vents to supply fresh air for combustion. If these are inadequate or blocked it can stop the fire drawing properly and can cause smoke/fumes to get sucked back into the room.

Also potentially lethal.

I would have thought that if it was a cold flue issue it would be difficult to light in the first place but from description it seems to start playing up once the fire has started to get established.

 

[superstardeejay]

That sounds like the cheapest thing to start off with. Dad is dreading having to take the stove out as being inset, it's sealed against the sandstone surround with high temperature silicone (which has already started to fail).

What's the procedure for fitting one? Do they slide up easily? I see they do flue-top cowls, various adapters for the stove etc. Do they have to be 'plumbed in' at both ends like a water pipe for example? What are the common sizes? Will we get one to slide up the existing clay liner? Do we need it inspected or is it a DIY job?

 

[superstardeejay]

Another thing to take into consideration is air vents to supply fresh air for combustion. If these are inadequate or blocked it can stop the fire drawing properly and can cause smoke/fumes to get sucked back into the room.

Also potentially lethal.

I would have thought that if it was a cold flue issue it would be difficult to light in the first place but from description it seems to start playing up once the fire has started to get established.

The builders incorporated an airvent when the room was built with a fireplace. The stove installers fitted a CO monitor when they fitted the stove.

 

[maltaron]

I feel that there is a lot of clutching at straws here, the fireplace never worked properly from new so there must be an inherent problem with design.

 

[stuart45]

What's the procedure for fitting one? Do they slide up easily? I see they do flue-top cowls, various adapters for the stove etc. Do they have to be 'plumbed in' at both ends like a water pipe for example? What are the common sizes? Will we get one to slide up the existing clay liner? Do we need it inspected or is it a DIY job?

You put them in from the top. Both ends needs to be fitted properly. They will go inside the clay liner. It does needs to be inspected unless done by HETAS.

 

[Norcon]

Inset stoves are less efficient than free standing stoves.
No air movement around the stove means the heat is trapped and travels up the chimney quicker and out through masonry to the outside.

Any stove installer using silicone to make seals should be viewed with utmost suspicion!
So what else have they done wrong? I wonder!
Maybe they have lashed it round the flue somewhere and its melted blocking the flue!

When the stove heats up to its full potential the silicone will disintegrate and possibly start a fire and belch dangerous fumes into the property!

 

[theprinceofdarkness]

Until the flue is hot, there will no great suction to get the smoke out of the stove. But THERE IS NO FORCE FROM THE FIRE TO CAUSE THE SMOKE TO GO INTO THE ROOM. The chimney is in a corner between two roofs, so I reckon that when there is no wind or wind blowing directly towards it, it will work (eventually), if the wind is blowing over an adjacent roof ridge, the wind will be turbulent and will have a downwards component to it. Think of it rolling over the roof. So I would make a flag or windsock and try lighting the fire when the wind speed is zero or its blowing in the correct direction. Prepare the fire well with enough fuel so it will burn for at least 1/2 Hr before it need to be topped up. See what happens.
Think of the flue as a column of air, when its hot, its lighter the the air in sky so your hot air floats upwards, dragging in cold air to be heated by the fire. So flue obstructions only hold back the maximum speed of this hot column unless they are total.
Frank

 

[88v8]

Sounds as if the flue is blocked. Your description of the way the smoke backs up suggests more than just lack of draw.

Maybe a muck-up when it was built, or perhaps disgruntled builders deliberately blocked it, who knows, stuff happens.
Or something as simple as a bird's nest.

If you have a cat ladder, get up top, remove that useless cap (this is good for solid fuel by the way)
http://www.ebay.co.uk/itm/Brewer-UF...ngs_Walls_Roofing_ET&var=&hash=item338e45ff52

and see if you can lower something down the flue on a rope. If you remove the baffle plate from the stove, the rope+weight should go all the way down into the stove.

You can also get camera surveys of flues, if you find a blockage.

Ivor

 

[superstardeejay]

Dad built most of that house so he won't have blocked anything!
Is there anything inherently wrong with an electric chimney pot fan? Won't that effectively overcome any lack of draw, whether caused by the roof level or cold chimney?

The inset stove is a high-efficiency one with a heat exchanger (like a balanced flue gas fire) and the heat comes out of a sort of vent above the fire area.

It's a Woodwarm Fireview 4kW like this:

Untitled

• superstardeejay
• 19 May 2014
• 1

 

[88v8]

Dad built most of that house so he won't have blocked anything!

That's good.

One of the chimneys in our previous house had draw problems when cold. This was exacerbated by the fact that there were three other open chimneys in the house, all of which drew better, so in effect they were pulling air down the weak chimney, even though there were open air vents in the room.
As a result, that fire could be pretty hard to light, and sometimes when it wasn't lit we'd get sooty smells due to the air coming down it.

However, from the way you describe how the smoke backs up, I would still check that the flue isn't blocked before you consider other measures.

Ivor

 

[superstardeejay]

definitely not blocked. The fire installer swept it before fitting the stove..although the original fire could only have been lit 10 times since new, so didn't need it. If there had been any blockage they'd have found it when they shoved their brushes up! It's also a straight flue from top to bottom so in theory once the fireback came out they'd be able to see daylight.

 

[stuart45]

If you do end up fitting a liner the appliance should burn more efficiently. A friend of mine who fits stoves and fires for a living said that the only problem is when people use wet wood on a slow burn, which he has seen block up the liner in less than a year.

 

[88v8]

Hmmm. Are there other open chimneys in the house?

Ivor

 

[Nige F]

Is there anything inherently wrong with an electric chimney pot fan? Won't that effectively overcome any lack of draw, ]

Nothing wrong at all - worth getting a quote for one

 

[superstardeejay]

Dad has had a quote from the installer of the stove to remove the fire, fit a liner and replace...they've quoted a grand.

The local plumbers merchants have quoted about £15 a metre (the chimney is 8m tall) plus around 20-30 quid for fittings.

How do we terminate the liner at the stove end? The stove is open at the back where it slides into the old fire hole and is sealed to the fire surround.