Air Vent for our Log Burner

[Phill123]

We have recently purchased a Log Burner for our Cottage - Clearview 500 with Low Top canopy.

Over the last couple of days we have been in contact with various HEATAS registered installers in the area, mainly to get the relevant certificate for insurance purposes. AND never realised what a difficult task this could! (Mainly caused by regulations that have been implemented in 2010).

What we have found is that each installer has their own views and what complies and does'nt! However as seen from the subject of this post, the main issue is the room in which the Log Burner is located requires an Air Vent!

Anything over 5KW requires an Air Vent and as ours is an 8KW this is a must. The issue is whereby all 4 walls in this room have stone walls that are 2 FT thick, and we have been advised that the vent cannot be located on the door.

Can anybody suggest a way around this, or maybe have had experience dealing with a similar issue.

Are there vents suitable for stonen walls this thick. In addition to this the cottage is grade II listed therefore cannot see the local CO agreeing to haveing an ugly air Vent on the side/front of the cottage!!!!

 

[Keith Bowman]

Presumably you don't have a suspended floor? (If you did you could simply open up a vent near the hearth.)

 

[Phill123]

Unfortunately floor is solid.

 

[88v8]

Unfortunately you're a bit sunk.
The vent only needs to be very small - a 5" hole with a core drill, and a cast-iron vent on the outside which the CO would regard as de minimis.
Then a brass vent on the inside, which some people might later replace with a hit & miss vent that would get closed in winter to keep the draught out, although of course I couldn't comment on that.
In terms of safety, if you have proper Period doors & windows, in practice ample air will come in for safe combustion. OTOH, if past owners have fitted inappropriate modern windows and doors and sealed up the house in a typically unhealthy modern fashion, a vent might be advisable.

More difficult in my experience is getting the chimney suitably lined, and capped with a terminal that effectively keeps the winter rain out.

Ivor

 

[Flyfisher]

I don't believe that a 2-foot thick stone wall should be problematic for a functionally suitable air vent, though it may certainly make the installation a bigger job.

I'd be surprised if a CO would object to a 5-inch opening in an external wall, especially if you have a wide choice of location and a 'period looking' outer vent cover, which are readily available (if a little pricey).

Regarding draughts, if you can locate the vent close to the stove then that should help matters. It may even be possible to locate it behind the stove, depending on the chimney/hearth arrangement, which would make it very unintrusive from the inside at least.

As for drilling the hole itself, I don't know what type of stone you're dealing with but there are specialist companies out there for this sort of thing. In particular, I've read of non-hammer-drill techniques that promise 'vibration-free' drilling, which might be helpful if, like us, some of your walls contain loose render/mortar/brickwork and a relatively small hammer-drilled hole can end up rather larger than anticipated!

Having said that, I've not yet used such services so can't vouch for their effectiveness but I thought it was worth a mention.

 

[agbagb]

Core drilling is good option but rubble infill can be a pain,hiring drill and a bit shouldn't be dear.

My Hetas chap mentioned the new regs say the vent has to be certain height from the floor now.

Is there a chance you can run duct down the chimney?

 

[eezageeza]

From memory, the actual vent size required is tiny - the trickle vents in our modern spec windows proved to be more than adequate to meet the regs when we installed our log burner (although this was earlier than 2010).

It may be worth checking exactly how many sq mm's you need from the regs, and seeing if you could more easily put something in a window frame.

 

[Penners]

Bite the bullet, buy yourself a core drill (2ft 1in long!) and drill a vent. It's a hell of a fag, but worth it in the long run: no awkward questions if/when you come to sell the house, and improved safety for yourself in the meantime.

 

[88v8]

From memory, the actual vent size required is tiny - the trickle vents in our modern spec windows proved to be more than adequate to meet the regs when we installed our log burner (although this was earlier than 2010).

It may be worth checking exactly how many sq mm's you need from the regs, and seeing if you could more easily put something in a window frame.

I think its 1 sq in per kw above 5kw. The Clearview 500 is 8kw, so that would be 3 sq in.
Unfortunately, the vent can't be in a window or door.

When you drill through the wall, it's b... hard work and you need a big drill, forget your usual B&D. Drill a hole that's the dia of a piece of plastic drainage pipe, and as soon as the hole is drilled insert the pipe to prevent the rubble core falling in, and mortar the pipe into each end of the wall.
Be careful to avoid overbreak as the drill comes out, best to put the pilot right through and drill the last inch or so in from the other side or it will look a mess, and may be harder to fit your chosen grille.

Ivor

 

[Zebra]

Mine is in the door and the Building Control Officer didn't have a problem with it.

 

[88v8]

Mine is in the door and the Building Control Officer didn't have a problem with it.

HETAS installers are self-policing, so BC wouldn't normally get involved in a simple installation.... Depends how jobsworth one's chosen installer is. Some of them take a real delight in banging on about The Regulations, and of course charging for the consequences.
If one could point out that the period windows & doors are 'draughty' and can't be changed, one might be more likely to get away with a door vent. Always assuming of course that the room has an external door.
Another factor of course is that if one will be sitting between the vent and the stove, one will be sitting in a mini-gale.

When we had our 5kw stove installed, even though no vent was required under the Regs at the time, I had two vents core-drilled through the back of the fireplace to ensure there was a good air supply without creating draughts. I was also slightly concerned that in the adjacent room, linked by an unclosable doorway, there is an 8kw stove from long ago with no vent, plus the kitchen linked by another unclosable doorway where there will be an aggressive extractor fan. All this pointed to a possible shortage of combustion air, with the stoves and the fan pulling against each other.
Our rubble wall is about 2 foot thick, and the guy doing the drilling really struggled. He's a beefy chap in his 30s, but he mentioned he's damaged his shoulder, and after watching him, I can understand why :shock: See below the drill he used.
I put hit & miss covers over the holes, so we can close off the vents when we want, and tbh I can't detect any difference in the stoves' burning with them open or closed, but the house is pretty 'draughty' and will remain so.

Ivor

Incidentally, see in the pic, the area of grey pointing low to the right - normally hidden by ye olde storage heater - the whole house was repointed in cement in 1972, and that's how it was when bought by PO in 1993. He carefully painted the pointing with masonry paint, a good aesthetic solution if not so good for breathability.

 

[Zebra]

At least it's nice to see you made him a cup of tea.

 

[Flyfisher]

Has anyone been given a sensible reason why a vent cannot be installed in a door or window, or is it just an arbitrary interpretation of the regulations?

 

[DJH]

Well I can't speak for modern day regulations FF but back in my day it was considered that a vent to outside was a more permanent way of getting ventilation or combustion air, to an appliance although, along with all vents, people will still cover/block/impede them in some way or another. Vents in doors which didn't lead directly to outside but to another room required that room to have a vent to outside or the room that it connected to needed one so that sort of increases the chances of one or more of those vents being blocked or not replaced when new doors were fitted for example.

Vents direct to outside are good...

No doubt the chap in the picture has just taken off his hard hat and ear defenders to have his cuppa... :shock:

Doug

 

[johnobirches]

Hi, I'm facing the same problem. Our burner is a Carraig Mor 20Kw from Boru Stoves in Ireland.

It requires a 8250 mm squared vent (on the 550mm2 for every kw over 5kw calc) which is nearly 4 inch square.

The stove is going in a double sided fireplace opening through an internal wall.

Rather than have a 4 inch square hole blasting cold air across the room I'd prefer to duct it to the stove through the side of the fireplace opening, but...

I have just read this on the Woodburner Warehouse website - "Air vents should not be installed into a fireplace recess except on the basis of specialist help. "

This is an extract from the Document J of the Building Regs on Stove installations.

Has anyone any experience of what this specialist help might consist of and what could be the problem of ducting the vent direct to the place where it is needed?

Thanks
John

 

[88v8]

- "Air vents should not be installed into a fireplace recess except on the basis of specialist help. "
Has anyone any experience of what this specialist help might consist of and what could be the problem of ducting the vent direct to the place where it is needed?

A registered HETAS installer.

I imagine he (or she) would be checking that the vent draws from outside not inside, and that the area from which it draws is free of fumes such as the output from a boiler or another stove.
On a suspended floor, ducting is (relatively) painless, and it may be that the existing underfloor air bricks already constitute an adequate vent if an opening is made into the fireplace.

Some stoves have provision for ducting the external air direct into the stove. That would be the ideal solution.

Ivor

 

[tobydog]

We have a rather old, chunky and inefficient wood burner in the lounge. It has solid doors and we keep them open so we can see the fire. It tends to burn more like an open fire than a roaring modern efficient burner. Also, with the doors closed, I'm forever having to get up and see if it's need filling.

We don't have any airvents in walls as such but we have our fair share of gaps around doors. The windows are actually quite tight. I can't imagine it draws a huge amount of air in and up the flue but I reckon these modern burner do. When these burners are rated, do the calculations ever take into account how much cold air the burner draws in either through the vent or other gaps?

It certainly makes sense to try and have the vent as close to the burner as possible so cold air get's sucked into the burner but if we rely on gaps all over the house, doesn't that somewhat counteract the effect of the burner in the first place? In our house it is snuggly in the lounge close to the burner but we need to play with the rad stats and move the thermostat to keep the rest of the house warm.

Just a thought.

 

[johnobirches]

Thanks Ivor - good point about possible fumes etc. near the intake.
Like the original poster we have a solid floor.
John

 

[Phill123]

Thanks for all the advice. Log Burner is now fitted and I have taken the plunge to Hire Drill + Diamond Core Bit.

Installer advised a min 2.5" bore hole with a decorative vent . Also air flow must not be less than 1650mm2 (I'm assuming he will check this!)

 

[Onetap]

The requirements for ventilation for solid fuel appliances are in the Building Regulations, Approved Document J, available on-line.

http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADJ_2010.pdf

It's quite straightforward and rooted in common sense. You can have the air vent in an adjacent room, a hall, for example.