Charnwood Downdraft fix with external air vent.

[Ratman]

I don’t think the top of stack is  1m above my ridge but I have only eye balled it..  I will have a look at regs but I really trust his install.  I watched him measure the co alarm position with pin point accuracy. 

Regs state 600mm above ridge

[Commando]

I have a grenadier stove heater which I had to use regularly in our last house. Great bit of kit

[openspaceman]

8 minutes ago, Gtflash said:

@openspaceman

 

I feel a direct vent might give the stove it’s own balanced system and help it.  Is there any disadvantage to direct air supply??  I’ve Googled loads and not really found any. 

In your instance I don't think so. Nearly all natural gas heaters are room-sealed with a balance flue and concentric air intake.

 

The big benefit is if the door seal is good and the stove is shut down there is no chance of CO getting into the room.

 

I don't recommend keeping the stove in as I think it important to maintain a flame to ensure clean burning.

 

[topchippyles]

10 minutes ago, Ratman said:

Regs state 600mm above ridge

That is the minimum height though surly.Fitted mine 10 years ago 

[Ratman]

That is the minimum height though surly.Fitted mine 10 years ago 

Yeah regs state minimum 600m above ridge, wont stop ya having it above/more than 600mm though.

[openspaceman]

17 minutes ago, Ratman said:

Regs state 600mm above ridge

Only if it is within 2300mm of ridge, if it is further it has to be no lower than the ridge but it must be 1000mm above the roof surface.

[topchippyles]

I have always worked to a metre which it was when i fitted mine 

[topchippyles]

2 minutes ago, openspaceman said:

Only if it is within 2300mm of ridge, if it is further it has to be no lower than the ridge but it must be 1000mm above the roof surface.

I had a metre in the back of my mind and the higher the better.

[Dan Maynard]

@openspaceman
 
I feel a direct vent might give the stove it’s own balanced system and help it.  Is there any disadvantage to direct air supply??  I’ve Googled loads and not really found any. 
 
fires lit last 2 days now.  Winds changed to NE and I’ve ditched newspaper and using 4 natural wax dipped fire lighters.  The wife stands by window and opens it if the fire lighters don’t roar straight away.  To be honest though there’s been no visible draft down chimney 

Surely if your wife opening the window makes any difference then that's a sure sign that ventilation is the problem? You need that external vent by the fire to equalise the air pressure in the room with outside, which is what is present at the top of the chimney.

I would have thought height of flue could be a problem but that would vary depending on if it's windy and which direction the wind is from.

[openspaceman]

40 minutes ago, Dan Maynard said:

Surely if your wife opening the window makes any difference then that's a sure sign that ventilation is the problem? You need that external vent by the fire to equalise the air pressure in the room with outside, which is what is present at the top of the chimney.

I would have thought height of flue could be a problem but that would vary depending on if it's windy and which direction the wind is from.

It's difficult to decide what's happening but it does seem that there is a circulation occurring that is causing  cold air to come down the flue until enough heat is warming the chimney so that it creates its own draught. The opening window business suggests there is a slight depression in the room normally so there must be something, like a heated bathroom upstairs with an extraction fan or just a warm room with a window open, causing this.

 

The same thing might  happen as the fire dies down and combustion products are sucked into the room.