Pulling fresh air to stove from Sollum?

[Niall]

TLDR: We have 7kW unvented log stove in a old house, but it draws air from the drafts. As I fit underfloor insulation and draft proof going forward is an air inlet from the sollum viable?

We've got a new 7kw fire in the living room and it doesn't not have the ‘required’ inwards air vent as the walls are thick sandstone, the exposed floor boards ‘vent’ hard and the house in general is ‘breezy’.

However going forwards were insulating under the floors joists and improving/removing some drafty doors, so the house will be more airtight.

Could I sink the air inlet down into the sollum?

Logic being drawing air out of there in winter is good as it keeps things circulating and helps keep the space dry. Plus prevents me creating a direct channel/cold bridge to the proper outside world. It's also where the air is defacto coming from now…

 

[Flyfisher]

We've done exactly that. A 7kW multifuel stove in the drawing room and the HETAS fitter said it would need an air vent with an area of X (I forget the number) to meet the regs. There was no way I was going to put a hole in the wall so, since the floor is suspended, I asked if two small vents each side of the fireplace would be acceptable and he said it would - and I have the certificate to prove it!

The floor is not insulated so it was only necessary to cut a hole in the boards. If insulated then it would require some sort of pipe (soil pipe perhaps?) or 'boxing' that extends through the insulation. Obviously it's important that the airbricks are not blocked and there is adequate ventilation under the floor. Bear in mind that as the stove draws in cold air, it will cause a draft so try to locate the vents as close to the stove as possible.

Having said all that, our house is also generally 'breezy' so I was never concerned about there being sufficient airflow for the stove and the vents are not actually necessary except for HETAS certification. I know this because the vents are covered with rugs and the stove still burns very well and the CO alarm has never gone off in the past 10 years or so

 

[Niall]

Cool that reassuring. Our model is 18m old an can have a vent connected to the rear of the stove. Fitter and me agreed it was worthless with 40 ‘vents’ running the full width of the timber floor, but post insulation it will be a different story.

Piped connection would kill the drafts but there will be a some cold bridging. My logic is its better to have that with the solum than the outside world.

 

[fernicarry]

The old solid fuel fire grate in our living room. a Baxi Burnall, took its air from under the floor. The vent pipe into the solum might have been asbestos. I think you'd want a metal duct rather than plastic and you might need quite a bit of clearance behind the stove so that the ducting can turn around to mate with the air inlet. Given that the hearth itself is the mother of all cold bridges I wouldn't worry too much about the addition of an external air intake. The stove we put into the fireplace has an external air intake straight into the back. Wall is only about 6" deep at that point so coring it didn't seem to be too much drama. The old asbestos pipe was repurposed to route the boiler pipework out under the floor. With the stove door closed you don't feel any drafts due to the air intake.

 

[a twig]

The old solid fuel fire grate in our living room. a Baxi Burnall, took its air from under the floor. The vent pipe into the solum might have been asbestos. I think you'd want a metal duct rather than plastic and you might need quite a bit of clearance behind the stove so that the ducting can turn around to mate with the air inlet. Given that the hearth itself is the mother of all cold bridges I wouldn't worry too much about the addition of an external air intake. The stove we put into the fireplace has an external air intake straight into the back. Wall is only about 6" deep at that point so coring it didn't seem to be too much drama. The old asbestos pipe was repurposed to route the boiler pipework out under the floor. With the stove door closed you don't feel any drafts due to the air intake.

I don’t think the OP has an existing pipe into the solum and is instead proposing to run one