Condensation

[joinerman]

Not car related

We have an open fire in our house which i built into the house 25 years ago, we have never ever suffered with condensation.
Last week we had a log burner put in, now even when it's not lit we are suffering bad condensation, we do have vents on most of the windows, are we alone or do any of you also suffer or have a cure

 

[Shayne]

I have heard of this before but i think Alzheimer is kicking in . Assuming they put a pipe from the burner up the chimney and sealed around it then maybe a vent alongside the pipe will let the stack breath .

 

[frank rabbets]

Other things being equal. Coal or coke burns at a much higher temperature than wood. As hotter air rises quicker than cooler air the coal/coke will cause a faster air speed up the chimney and change the air in the house quicker getting rid of the moist air. Also if your room temperature is cooler with the wood you are more prone to condensation as cooler air cannot hold as much water as hotter air. Ventilation is very important so that moist air cannot build up in the house. Ideally you need high room temperatures and ventilation, something which the environmentalists don't want to talk about because obviously you get heat loss.

 

[moggy1968]

yes Frank, I find this whole concept of modern houses being a sealed box a bit odd. To my mind a house has to be able to breathe. both for health reasons (having fresh air to breath rather than stale stationary air) and for reasons of condensation etc where a good airflow is essential. I understand the ideas about heat loss but in terms of air quality and actual livability, I don't really get it!

 

[Paddler Ed]

In my parents last house (built in 1985/6) when they had a fireplace fitted they had a hole cut in the concrete floor so that there was a bit more air flowing into the house.

Their current house on the other hand is a slightly drafty 1800's one, so has the natural breathing that prevents excessive condensation...

What the solution is? Not sure...

 

[clivehorridge]

I shared a house that had a wood burning stove, but of course that was sealed with a glass door, so water vapor from the fire went straight up the flue.

An open wood fire would release the moisture from the wood, into the room to some extent, as it burned and released that vapor, so I can understand the problem.

I can only suggest more ventilation for the room, so that the condensation is dispersed more rapidly. That may even need a window to be opened, somewhat defeating the object of having a fire at all.

In the old days, folks were not so bothered by condensation, they learned to live with it. These days, for obvious reasons, we've been accustomed to a dry, moisture free environment in our houses, which may not be so healthy as we've been led to believe.

Again, other than as above, what to do about it is something to ponder. De-humidifiers are expensive, both to buy and to run, but they are an option.

 

[Shayne]

Had to dig deep to remember but yes put a vent leading into the stack i've done it before twice . Thinking about it an open fire draws air from the room pulling fresh air through the vents in your windows . Plants are also good to absorb moisture .

 

[Tractionman]

Only if you don`t water them (lol)

 

[Towpack]

Plants lose water to the atmosphere by transpiration, drawn up from the root system and will add to the humidity/condensation. De humidifiers will certainly cure the problem but at a running cost. More ventilation will also work but the trick is getting enough airflow without having a gale blowing through the room and taking all the heat with it!

 

[joinerman]

Thanks for all the replies, we do have a vent directly under the fire, you can see this in the back of the floor in the picture, it disappears under the floor & up into a boxed out skirting right through to the outside wall with a 9x6 vent through the wall, it's worked fine with an open fire for the last 25 years

 

[frank rabbets]

Looks like you need to draw air through the room instead then? Do you think room temperature is cooler with the wood? If so that's the answer.

 

[silvercruiser]

. Pants are also good to absorb moisture .

Especially if you have been near the Guinness

 

[MuckyPup]

The problem is the difference in airflow.
The open fire drew air from the vent AND the room for combustion but it also dragged excess air along with it and sent it up the chimney, The wood burner is drawing fresh air from the vent for combustion but isn't drawing that extra air along with it.
hence the effeciency figure jumping from 20% to 70%
You've also severely reduced the air exchange going on in the room which is why mechanical heat recovery ventilation is becoming more common.

 

[frank rabbets]

Yes the air vent will have a certain resistance to air flow. The quicker the draw up the chimney the less the vent will cope thus drawing air through the room and removing damp air. I think there will be a quicker air flow up the chimney with coal/coke, that's why this problem has suddenly occurred.

 

[Shayne]

Cheap experiment , block half the vent and see if there is a difference . In fact block the whole vent if the burner works fine without it you don't need it and there's plenty of drafty leaks in the house to feed it .

http://www.doityourself.com/stry/5-indoor-plants-that-will-absorb-the-humidity-in-your-house