Heat, Mould & Condensation

rogerblack

Herongull wrote: »

You can get cheaper quieter de-humidifiers eg peltier types rather than compressor types.

They take water out at a slower rate than the compressor types, but claim to still be suitable for small rooms.

These are however considerably less efficient than a compressor type.

The above takes 70W, and produces 600ml of water a day.

Air at 20C and 80% humidity has about 17g of water/m^3.
At 50%, 11g.
So, it can dry about 100m^3 of air to 50% from 80%.
This seems like a large volume - however a 4*4*2.5m room has 40m^3.
So, if this room has more than two air changes a day (very, very well sealed, too good for building regs), it won't cope.

A conventional compressor dehumidifier will use about the same power, and extract around 10* the amount of water.
(or conversely, need run for 30 mins a few times a day on a timer)

The costs can rapidly add up - the above unit will use 70 quidish a year of electricity if you use it all the time.

oldskoo1

trinity_p wrote: »

Hi everyone, its been a little while but I thought I would update in case anyone else stumbles across this post in the future. We purchased the dehumidifier as advised and wow what a difference! We have it turned on most days (but not night), we keep it upstairs on the landing and monitor the humidity level with the digital reader we purchased from ebay, it usually says around 52-54% which seems to be an acceptable level to allow us to be MOULD FREE! We have gone from cleaning my sons ceiling/wall weekly to never having to clean it all all! We have had to clean mould from our room twice since our purchase but thats only been a tiny spot in the corner and we do dry all our washing in their so we did expect it.
Cannot rate the dehumidfiers enough, they have changed the way we live, its so nice to know my son is in bed breathing mould spore free air!

A big thanks to all who had input and helped us deal with this issue!
Trinity

I'm glad it has helped!

I am curious what type of wall construction your house has? Does it have a cavity and is this filled with some type of material?

You sound like you have a lot of moisture, drying clothes in doors, open plan living, cooking shower etc doesnt help with no extractors or poor ventilation but this sounds worse.

I'm no expert but aside from having a roof leak or having a new patio covering up brick ventilation, i'm wondering if the house either has no cavity, exposed to the rain or has a cavity but it is filled and the cavity is transferring damp to the inner walls. Possibly no air ventilation in the roof space neither.

The house with the least condensation i have lived in is our current house which gets hardly any no matter what we do. Sometimes a tiny tiny patch of droplets in the bottom corner of the window in just 1 room that i have noticed. This house has a cavity but it isn't filled.

Previous house had a filled cavity and regardless of ventilation every morning the windows were dripping and had to be wiped cleaned. Trickle vents or opening the window did nothing. Surely if there is excess moisture in the air and inner leaf this takes more energy to warm up? Curious.

Filligreefairy

I appreciate you've settled the issues now, but thought I'd add my input for anyone reading this going forward - we have a massive mould issue in our bedroom, were the window/wall combination does not seal well and have been using Homebase Mould Cleaner every 6 months to kill it off. It's not the most ecologically friendly - you shouldn't wash it down the drain - but it keeps the mould at bay for the full 6 months, and is easy to apply.

We also recently invested in a dehumidifier - Argos value 10 litres/24 hours - which has made a world of difference.

rabialiones

we suffer from mould in bedroom in house we recently moved into. there is no evidence of previous such problem as walls were very cttlean when we moved in.
had loft insulated and wooden gutters replaced with twinplas guttering.
could either of these be the cause of the mould

rogerblack

rabialiones wrote: »

we suffer from mould in bedroom in house we recently moved into. there is no evidence of previous such problem as walls were very cttlean when we moved in.
had loft insulated and wooden gutters replaced with twinplas guttering.
could either of these be the cause of the mould

Loft insulation which obstructs vents for the walls can cause this, yes, as can gutter installation that blocks vents, or is leaking into the house.

rabialiones

think it may be the loft insulation as the gutters just replaced the wooden ones.
how do i go about checking the loft vents, or should i contact the installers

rogerblack

rabialiones wrote: »

think it may be the loft insulation as the gutters just replaced the wooden ones.
how do i go about checking the loft vents, or should i contact the installers

You can get up into the attic, and look at where the roof meets the walls.
There will be a gap to provide ventilation going from the wall into the roofspace.
If this is completely covered, damp can result.
You can of course call the installers, but they are likely to deny it's them.
Of course, while you're up there, you can also see if you've got leaks in the roof.

rabialiones

will have to get into roof space somehow and check it, never been in there before, hope i dont slip into bedroom below

Fire_Fox

rabialiones wrote: »

think it may be the loft insulation as the gutters just replaced the wooden ones.
how do i go about checking the loft vents, or should i contact the installers

Are you ventilating the bedrooms and bathroom properly by opening the windows daily year round? Don't underestimate how much water is released simply by breathing overnight and by showering, if that is not let out of the house it will settle and cause mould. I get horrific condensation in winter when there are two sleeping in my bedroom, some condensation with one person, little when I ventilate daily.

Andy_WSM

Not heating your sons room will be adding to the problem here too. You need to keep his room at the same temperature as the other rooms upstairs. Reason - the warm damp air from the rest of the house will rush into the colder space and the humidity, already talked about, will condense on the colder surfaces in his room.

Some really good advice in this thread.