The Blog this week is about:
Myths and mis-information regarding Condensation & Moulds
There are Company websites proclaiming they are ‘experts in condensation and mould issues’. They state things like: ‘Get the professionals in’, ‘The condensation experts’. But should you believe them?
How do you know if they are just a website that states ‘pseudo facts’ that are nothing more than just myths? Even Local Councils and Housing Associations get taken in.
Look at some of their facts and compare with actual proven science:
Opening windows
‘Open the window and let all the steam out’ – It helps very slightly however doesn’t do much at all to reduce the condensation around the home. As mentioned in a previous blog dry air is molecules of nitrogen (78%), oxygen (21%) and trace gases (1%) with space in between them.
Humid air is dry air with water molecules (vapour) in the spaces.
Water can be solid as ice, liquid as water or gas as vapour. The molecules are exactly the same with a ratio of 1 hydrogen atom to 2 oxygen atoms (H2O).
Water can vaporise at temperatures well below boiling point (100°C). The evidence is water evaporates from the oceans and seas etc. Leave a glass of water and eventually the water will evaporate. (If you want to find out more it will be in Construction Science Explained – www.buildabooks.co.uk out next year).
The atoms of a water molecule remain the same whether it is water, ice or vapour. As vapour they can float in the spaces between the other gases in the air. That process is termed humidity.
A common ‘myth-statement’ ‘Steam is water vapour’ . Not true. Steam is water. It is water vapour that has condensed in the air therefore it is actually condensation and visible. Gases including water vapour are not visible.
Molecules are more than one atom. It can be the same type or different types termed compounds. Either way although they do not have a weight as such (Atoms have an atomic weight that is a comparison with a carbon atom). Atoms do have a mass though. That mass can be attracted by a greater mass. The greater the mass the stronger the attraction. (Similar to weight).
The planet Earth is made up of an enormous number of atoms. The combined attraction (pulling force) we call ‘gravity’. It’s a bit like a very large magnet will attract a smaller item such as a nail. The nail if magnetised will attract a smaller pin, and so it goes on down the sizes.
Gravity however is a strong attractive force that can go through most things and still attract. It can go through the tallest buildings and still have an effect on an aircraft flying at 35,000 feet in the air. So logically it also has an attractive force on every atom be it in a solid (the aircraft), a liquid (rain comes downwards) and the gases.
If it didn’t have any effect on the gases they would all have gone off into outer space. Irrefutable evidence: the higher the altitude the less molecules. We state that the air is ‘thinner’. What it actually means there are less molecules, less nitrogen, less oxygen etc. and a lot more space.
So what has all this proved?
Air can be dry – no water vapour in it. Very rare though, most air has some water vapour in it even in the hottest deserts.
Atoms have a mass. The more mass in the same volume means there is more atoms for gravity to act on. We term that ‘weight’. If you could take say a gold bar that has a weight on Earth of 6kg then send it to the Moon it would then only weigh about 1kg. The gold bar hasn’t changed, it still has exactly the same number of atoms in it. The only difference is the attraction force ‘gravity’. The Moon is that much smaller so less atoms to to do the attraction.
If air is heated the molecules will become more energised. They will move more quickly and collide with each other. The collisions tend to end up as the molecules bouncing off and going in a different direction to their next collision. All the time that is happening gravity is trying to pull them down to the lowest point and slows them down The result is less collisions = less heat generated = the air cools down.
If a
cubic metre of air is considered there will be a given number of air molecules
in it at a specific temperature. If the molecules are given more heat (energy) they
become more energised and travel faster and further. There will be fewer
molecules in the cubic metre as the temperature rises. Fewer molecules means
the pull of gravity has less effect. The cooler air will push the warmer less dense air upwards. Warm air rises and that is the reason why.
Evidence: the attractive force of gravity can be compared to magnetic attractive force. The closer together metal particles are the easier the magnet can attract them (ignore friction).
Warm air is less dense than cooler air as there are fewer molecules for gravity to act on. Warm air therefore is displaced by cooler air that has more molecules in the given volume. The end result is warmer air will be pushed upwards by the cooler air trying to get as low as possible.
That was considering dry air only; Nitrogen, oxygen and trace gases argon and carbon dioxide. Now add water vapour.
Water vapour (H2O) has mass so will be attracted by gravity. The more vapour that can fill the gaps in the dry air the denser the molecules. The more effect by gravitational pull and the air is effectively ‘heavier’. At the same temperature the humid air is going to sink. As is sinks it displaces (pushes) the drier air out of the way. If there are walls then the only place the lighter drier air can go is upwards.
It is said it ‘rises’ but it is actually it is being pushed upwards by the more dense air. (Nothing can go upwards without energy being used, not even atoms).
So dry air is less dense than humid air at the same temperature. The warmer the air the fewer number of molecules therefore they get pushed upwards (rise).
The air in the shower will be saturated with water vapour. At its maximum temperature the humid air will be pushed upwards by the cooler air. If an extractor in the ceiling or high up the wall is close to the shower outlet it will pull the humid air out of the room.
The hot water will be flowing over the person and surfaces of the materials around the shower (walls, shower curtains, panels etc.). Those surfaces will be cooler than the hot water but as there is so much water any condensation will blend in with the water.
The surfaces will warm up via heat transfer from the hot water. They will also cool the water down in the process. (example; water at 40°C and surface at 20°C will become about 30°C)
The air around the shower area will be cooler still and condensing the vapour into steam. The visible condensation in the air, steam will further condense on cooler non-porous surfaces to form globules of water. The molecules of the surface material attract the water until there are too many water molecules to support and the globule is pulled downward. Commonly known as ‘streaming’.
The bathroom / en-suite door if closed is keeping much of the humid air in that room. The extractor is pulling the humid air out at a design speed (we will come back to that in a moment). Air, humid or dry cannot be pulled out of a room unless other air is going in to replace it. (otherwise you would end up with a vacuum).
The gap under the door
If the gap under the door is at least 10mm (3/8”) it will let enough air in to the bathroom / en-suite to replace the humid air being pulled out.
For those who are interested: If the door is 762mm wide (2’-6”) then the gap area will be 7.62x10-3m. A pipe 100mm diameter will have a cross sectional area of 7.85x10-3m which is slightly more meaning there will be a greater negative pressure but not enough to worry about.
The gap is normally at the lowest level in the room where the air is at its coolest and most dense. It cannot escape under the door as there is a negative pressure (suction) as the extractor is pulling the air out of the room.
Why do I need to know all that?
Simply having an efficient extractor running before the shower goes on (or running a hot bath) will start the negative pressure so any humid air will be going out of the extractor outlet as opposed to building up in the room.
Opening a window – Hmmm. Based on the science it isn’t going to do much. The main objective is to pull the humid part of the air out of the building and opening a window will not do that.
Having an extractor going with the window open isn’t much good either. It is likely this time of year that the air outside will be much cooler than inside your home so all the extractor will be doing is cooling the room down so it condenses the vapour quicker.
The window is unlikely to be at floor level so all that cooler humid air will still be there. Open the door and it can then roll out into the rest of your home.
Bottom line: Efficient extractor operating before the humidity rises in the room. Door shut and the drier warm air from the rest of your home is used to replace the humid air being extracted. Extractor continues to operate for about 30mins after the shower has stopped. (Door still closed or just very slightly open). That will remove the humid air that is formed by water evaporation. By wiping up as much as possible any water or condensation left on the hard surfaces around the shower it will reduce further humidity.
As an experiment use a container to catch all the water you ring out of the cloth used to dry the surfaces. That would have all had to evaporate into the air. Leaving the extractor on for 30 mins will help to remove the rest of the water you haven’t mopped up.
Extractor efficiency.
The manufacturers provide figures showing how many cubic metres of air an extractor fan is capable of pulling down a tube per second, per minute, or per hour. Some extractor fans have an adjustable amperage meaning the amount of energy used to turn the blades of the fan. More revolutions normally equals more of an air flow.
Air in a room will fill the whole volume and all volumes of containers in it such as drawers, cupboards, wardrobes and that includes the waste tubes in the shower tray, bath, basin and inside the pan and water closet of the WC.
Air naturally contains pollutants including mould spores as mentioned in a previous blog.
Mould requires moisture to enable it to absorb food. No moisture = no absorbed food = no growth. Mould can grow down inside the plug hole tube and into the water trap. A slime builds up and the mould feeds off of that. The tell-tale sign that mould and slime are growing is commonly the smell. Bleach will kill the mould and to a point dislodge the slime from the pipe.
Ideally pour the equivalent of a tea cup full down the plug hole and leave it overnight. Then put the plug in and fill the basin with water (hot or cold it doesn't really matter - however hot tends to work better. When the basin is full pull the plug out and let the water flush the waste pipe through.
It is surprising the amount of slime and hair that will be flushed out. A bath trap can produce about a cup full yet still allow water to go through albeit slowly.
Water is not pure H2O. If it were then you wouldn’t want to drink it as it would taste horrid. Tap water contains minerals that are dissolved in water. Calcium for example naturally occurs in water. It is an essential mineral for our bones and all other creatures that have bones or shells. Chalk is basically Calcium (Calcium Carbonate) formed from the bones of billions of creatures over thousands or millions of years.
Another mineral naturally occurring in water is Magnesium.
Magnesium calcite is derived from chalk (the skeletons of those billions of sea creatures). When rain water (which is slightly acidic) goes into the ground it dissolves minute parts of the chalk. A bit like putting sugar in a hot cup of tea. The sugar dissolves and it all becomes liquid.
Potassium is also a naturally occurring mineral in the ground and dissolves in water.
How do the liquefied minerals help mould to grow?
Compare minerals in water with sugar in a cup of tea. Leave a cup of tea and eventually the water content will evaporate into the air (that‘s if no-one drinks it first). The sugar in the tea cannot evaporate and the molecules join together to form crystals. The crystals are very hard and tend to be brittle. They will bond to most hard surfaces producing a coating of sugar crystals.
Now compare that to the water from the tap. Water that contains a large quantity of minerals in solution (dissolved) is termed ‘hard water’. The minerals are in solution, i.e. in liquid form. The molecules are attracted to other molecules causing bonds.
Calcium is a naturally occurring element, a metal by definition. It can exist in water as solution, i.e. liquid, or as a solid commonly termed limescale. When water passes over other materials some of the molecules of calcium bond to them causing a coating. The higher the temperature of the water or the material the water is touching boosts the bond. The result is the calcium solidifies and coats the material. The most common form is calcite (calcium carbonate). It is a form of limestone giving the term limescale. Basically it is a stone-like coating that slowly attracts more calcium out of solution.
In something like a washing machine or dishwasher where the cold water is heated via a metal heating element the formation of calcite in hard water will occur. (That will be the subject of a future blog – Is it cost effective to stop calcite forming in hard water areas?)
Calcite will also form when the water molecules evaporate. If you live in a hard water area your kettle heating element probably ‘scales up’ – has a crust of calcite coating it. There is also probably calcite around the outlet of the taps and plughole material. If there has been a leaking or dripping tap there will be a deposit of calcite where the water has been.
Calcite will bond to the glazing on the WC chinaware. In the water trap the calcite will bond to the sides, under the rim of the pan and in the water closet box. The surface of the calcite will be rough and porous. What else is in the water? Without putting you off drinking water sufficient to say there are lots of things. Some are in solution and others still as very small solids termed 'as in suspension'.
Some of those ‘solids’ stop off at the calcite and some of those are made up of carbon – and mould thrives on carbon. A different strain of mould but still blackish in colour is able to absorb the carbon and set up home. The occasional flush just brings more food so the mould is quite happy. The flush isn’t enough to wash the mould off.
A few bacteria in with the mould and you now get manufacturers advertising their products ‘Get rid of 99.9% of all known germs’. But there isn’t such a thing as a germ. The word originated in the Victorian period to baffle the uneducated.
Originally the word was derived from ‘germinate’. Plants seeds germinate so the clever Victorians who were dab hand at explaining things like poo etc. told people that bacteria in particular grew (from what I don’t know) so they called the process ‘germs’. Bacteria multiply from a living cell, not a seed so no germination. They replicate forming groups of cells termed a colony.
Moulds grow from spores and not seeds so they can’t be classed as germinating either.
Bleach certainly does kill most things depending how strong the solution is and how long the contact is. There are various types of bleach. Bleach used to strip the colour from hair contains oxygen in the form of hydrogen peroxide.
There is chlorine bleach that contains sodium hypochlorite and sodium hydroxide. That’s the bleach used to clean the loo.
Will bleach dissolve calcite though? No is the easy answer. It will burn the cells of the mould and kill them on contact. It will take the colour out of the calcite if there is any (very light grey if it is thick enough) but there isn’t enough acid to dissolve the calcite.
One of the tests geologist use to distinguish limestone from sandstone is to drip very diluted hydrochloric acid on it. (About 10% dilute). Limestone will fizz violently and gas off as carbon dioxide.
It is not recommended that that strength is poured down the loo though. There are products that contain hydrochloric acid that will dissolve calcite. When hydrogen chloride is mixed with water it forms hydrochloric acid. Other solutions are added that bond with the hard surfaces so that the hydrochloric acid remains in contact with the calcite as opposed to just running off.
If the calcite is removed the china surface will not allow other minerals (plus other organisms that are naturally in water) to stick. No food for the mould to feed off = no mould. The problem is that even using the ‘duck’ shaped bottle it is impossible to squirt the limescale remover into the box section ducting that is behind the loo pan rim so it continues to lurk there.
Don’t be tempted to put it in the water closet box either as it will rot the neoprene gaskets and ‘o’rings and they will leak.
Conclusions:
1. Opening a window doesn't actually reduce much condensation.
2. Moulds multiply by replication and need moisture. They do not have multi-cellularseedsrequiring germination.
3. There is no such thing as a germ. It belongs in a pot with hobgoblins, the bogeyman, fairies and so on.
4. Bleach will not remove calcite (limescale). Hydrochloric acid dilute is required. [Vinegar will dissolve calcite but take much longer to do so].
5. Humidity is the amount of water vapour in the air. Condensation is the result of water vapour condensing.
6. Humid air is more dense and will readily fall to the lowest point displacing drier air upwards.
7. To reduce condensation water vapour in the air needs to be removed.
The next blog continues with the myths propagated by so called experts. We will be looking at some of their claims.