I thought I would ask here as its just as good place as any.

I have a house, built in the 50s by the look of it, made of fibro. It has ceiling vents in each room including the living room and the kitchen. It is clearly made to have a wood fire for heating as there is a newer woodfire and an older chimney that has been blocked off. I have split system aircon that I prefer to use.

The question I have is are those vents still needed? In this day and age of insulation, do they serve any purpose? I have added a lot of ceiling insulation, but those vents are still clear. At least the ones that aren't blocked with 70 years of dust.

Do I need to leave them there, or can I block them off so that warm air doesn't float off into the roofspace?

I blocked mine off for a considerably warmer house in winter.

Ana old house like that isn't going to have trouble breathing. thru all the other gaps.
Ceiling vents just remove hot air, block them off.

TV programs about English houses, say block all drafts, they even pressurise the house to see how much it leaks. Not sure what happens to their CO2 output, but you won't have that problem.

Select to expand quote

FormulaNova said..
I
The question I have is are those vents still needed? In this day and age of insulation, do they serve any purpose?

I wondered about that. One day on ABC radio you'll hear one eco whiz telling you to stop all the leaks to safe energy consumption. And the next day it's ventilate, ventilate , ventilate by someone into indoor air pollution. (I worked alongside an indoor pollution specialist once, he would never buy a new car. "Get one 3 yrs old" he said, "after most of the volatiles have been boiled off").

But anyway it seems it's best to have the air in your house exchange once an hour so all the nasty vapours from all the plastic rubbish you have accumulated don't build up.

Air has a specific heat of 700 joules per kg per degree. A density of 1.2 kg per cubic metre. You live in a moderately sized house of 300 cubic metres. You set your climate control to plus 10 degrees C. So that's 360 X 10 X 700 joules every hour to reheat the exchanged air. Divide it by 3600 = 700 watts 0.7 kW.

So before you block those vents determine how much air is exchanged in an hour.

yes you need air exchange, but in Winter, not from ceiling vents. That's where your hot air is.

When I got the gas bayonets sealed up (no longer using fixed gas heaters around the house) due to them leaking, the plumber suggested that we no longer needed the vents that were in the ceiling and walls.

Perhaps they used to be a requirement when people used combustion appliances more inside their homes?

Select to expand quote

decrepit said..
yes you need air exchange, but in Winter, not from ceiling vents. That's where your hot air is.

Yeah, its a challenge. Do you get airflow or keep the energy from flowing out the vents?

I installed those vent shutter things from Bunnings for a place that had open vents up high in the walls. In summer it was great as the hot air just flows out. In winter it was terrible as the hot air you are trying to keep just wafts away. Hopefully the new vent shutters fix that.

The place clearly has a thermal layer as I found when changing light bulbs. Standing on a ladder felt like you were in a sauna. One of the best things though was having ceiling fans installed to mix up the air both in summer and winter.

I ended up blocking the vents in my original question. The thing that made it clear was that smoke from the neighbours place was actually coming into the roofspace and then through the vents into the room. Once I blocked them off it was better, although I am worried that the neighbours wood smoke gets into the house so easily.

Select to expand quote

decrepit said..
Ana old house like that isn't going to have trouble breathing. thru all the other gaps.
Ceiling vents just remove hot air, block them off.

TV programs about English houses, say block all drafts, they even pressurise the house to see how much it leaks. Not sure what happens to their CO2 output, but you won't have that problem.

One thing that is confusing me about this house is that in winter the air inside seems cleaner when you run the wood fire. When you don't it seems more smokey.

This is in Collie. so everyone else around you has a wood fire and smoke just sits in the valley. Yet if you have the woodfire going its almost like it is cleaner air. If you don't its like the smoke from outside invades the place.

I am suspecting that somehow the fire is consuming enough air and it somehow draws in a lot more that it is fresher, or the hotter air somehow keeps it out, or I am just not noticing it because of the blazing fire in the loungeroom.... anyone know??

well the fire would create a convection current, out the top and in the bottom. If the air at ground level is clearer than the air at roof height, that would explain it.

Select to expand quote

decrepit said..
well the fire would create a convection current, out the top and in the bottom. If the air at ground level is clearer than the air at roof height, that would explain it.

Maybe that's it. It seems crazy, but I am sure it's the case that it smells less smokey when the fire is going, but as you say it could be drawing in all the colder air below the smoke.

I now have a problem in that I need to talk to the neighbour and find out if they can fix their flues. Neither of them appear to be at the correct height and both seem to flood my house with smoke when the wind is blowing its regular direction. I don't think people realise that you can't just stick up a chimney anymore and that there are rules meant to avoid this sort of problem. As it is, with their 'too low' flues, the smoke rolls across their roof and into my house...

I like wood fires but I would be happier if they banned them everywhere!

Surely in Collie you burn coal not wood????

There's smoke everywhere here this morning, just a coincidence, it's the first cold night???????

Select to expand quote

decrepit said..
Surely in Collie you burn coal not wood????

There's smoke everywhere here this morning, just a coincidence, it's the first cold night???????

Surprisingly, at least to me, coal seems quite hard to come by. I guess you need different fireplaces to actually burn it. Whereas at least in Collie, you are in the middle of forests, so firewood seems plentiful. I think a true local gets a delivery of decent firewood and stacks it up, whereas I only visit now and then and buy a bag of it from the hardware.

I think some people there burn everything and the smoke coming out is pretty bad. I think if I lived there all the time I would be investing in an air purifier or something. All that smoke cannot be good for you.

Green timber straight off the tree will do that

Select to expand quote

decrepit said..
Green timber straight off the tree will do that

Yep, I think a lot of people around turn burn anything to get their fire started. To be fair, when the fire is fully ablaze I will throw in other stuff too, but only when its at the point where anything just burns up quickly.

But the fumes I get from the neighbour's wants me to go over there and try and teach them how to light a fire. They have been there for 20 years so you would think they would know... but instead you get a fumey black cold smoke.