Ventilation for open fire?

LindaLou72

And we're looking at an open fire, which apparently necessitates the vents no matter what. I was told that if we decided to install a solid fuel burning stove instead, anything over 5 kw would also require the vents. I didn't ask about a gas fire, since we just removed ours and don't want another. The open fire would be ideal, really. I'm thinking no one is going to haul us off to jail if we find a way to close the vents when we've not got a fire burning - that sounds like the best plan to me.

wrightk

Crinkmeister wrote: »

Doesn't the need for a vent depend on the rating of the fire? I thought there was a 7kW threshold. Maybe your fire has a higher rating than 7kW - although I'd doubt it. However, assuming your fireplace shop man is Gas Safe registered, then he should know his stuff.

Actually for solid fuel appliances the threshold is 5kw, then every kw above 5kw the size must go up by a certain amount (mm2)

guidance can be found on hetas website regarding open fire ventilation, see below;

For simple inset open fires with a throat the guidance states that the following air requirement is necessary based on the width
of the fire opening:-
350mm fire opening = 14,500 mm2/145cm2
400mm fire opening = 16,500 mm2/165cm2
450 mm fire opening = 18,500 mm2/185cm2
500 mm fire opening = 20,500 mm2/205cm2


For the larger opening your looking at a 125mm through wall vent, i wouldn't go for two smaller ones. You want the vent nice and low down (less than 45cm high) and as close to the fire as possible, this will help reduce drafts in the house


More info can be found here

http://www.hetas.co.uk/wp-content/mediauploads/Ventilators2.pdf

wrightk

LindaLou72 wrote: »

Thank you - I will have a look at that. There's a bit of a problem in that if we let the company do the fitting, they will want to install vents that don't close, and then we'll have to adapt whatever they've put in. I wish we were better at DIY - it would make things easier!

It is very simple to install a through wall vent providing you follow the guidance on hetas regarding the maximum height etc. You will need to hire a core drill for a few hours and use a core that gives you a 125mm diameter (or whatever size is needed). You then simply slide some rigid ducting (available everywhere screwfix etc) through the hole, leave around a cm each side of the wall overhanging, slot your internal and external grilles (again available everywhere for a couple of quid) into the ducting and attach the grills to the walls using four screws

wrightk

LindaLou72 wrote: »

And we're looking at an open fire, which apparently necessitates the vents no matter what. I was told that if we decided to install a solid fuel burning stove instead, anything over 5 kw would also require the vents. I didn't ask about a gas fire, since we just removed ours and don't want another. The open fire would be ideal, really. I'm thinking no one is going to haul us off to jail if we find a way to close the vents when we've not got a fire burning - that sounds like the best plan to me.

There are many products you can buy with sliding grills to close the vent. As they are made out of plastic the 'closed' position never really fully closes it so there is always some trickle ventilation but when closed it does stop the worst of the drafts

Important to remember aswell that the regs aren't just there for safety. Any fire needs oxygen for combustion and your fire will run/chimney will draw badly if there isn't enough. The heat loss from the vent will be negligible when the fire is running

DigForVictory

Our fire runs like a dream because of all the 'natural' ventilation. We do not read newspapers - it's too hard to hold them. So open fires definitely need air coming in, and how you choose to accomodate that is your call.

Have you checked the chimney will cooperate? As m'lady other found that if she burned coal, the master bedroom reeks (chimney not lined) whereas wood, peat & even dry manure (historians can be challenging guests) were fine.

Oh aye & CO alarms, whilst less than visually lovely, beat coroners verdicts every time.

A last thought - how do you propose to empty the ash etc? When & into what - we had to buy a 'traditional' rubbish bin as the council issue plastic things were clearly marked unfit for that purpose.

If you can get it all working, a real fire is great fun, but please check your chimney as in a semid? You may be gassing your neighbours...

Paradigm

An open fire consumes far more air than any closed system (woodburner/roomheater) & not just for the actual burning of the fuel, the pull of the chimney can require something like 260 cubic metres of air per hour for a large open fire.
Insufficient air will prevent the chimney doing it's job & will cause the fire to smoke into the room...
As DigForVictory has said, you must make sure your chimney/flue is suitable for the fire you have in mind.


Another point, all you need to ensure is that enough air is entering the room for the fire to operate properly... this doesn't have to come from outside!
You can install vents to the hallway or other rooms, this air will be considerably warmer than air from outside & will lessen cold drafts.

southcoastrgi

The grave yard is full of people who thought they knew better

LindaLou72

Thanks so much for all the helpful advice. I'll take my time looking through everything carefully, and will share it with my husband. You guys are stars x

Grenage

Paradigm wrote: »

enough air is entering the room for the fire to operate properly... this doesn't have to come from outside!

Sure it does; any air pulled in from other rooms is going to lead to the same problem.

Ventilation is no bad thing.

Paradigm

Grenage wrote: »

Sure it does; any air pulled in from other rooms is going to lead to the same problem.

Additional ventilation for the room to satisfy the ‘demand’ caused by the pull of the flue can usually be
provided without resulting in unpleasant cold draughts. Fitting a louvred grille or adjustable ventilator
over the door to the room will draw air from the hall which is less cold than the outside air.

http://solidfuel.co.uk/pdfs/curing_chimney_problems.pdf

Was just a (valid) suggestion.