How to address my humidity issues

ComicGeek

Aloysius1972 said:

ComicGeek said:

WIAWSNB said:

Aloysius1972 said:

I see the heat vs ventilation debate still rages! In the end condensation control is surely a balance of temperature (air and surface) control, humidity extraction, ventilation and circulation? Can it really be controlled by one of those in isolation?

Yes. But. 

To only ventilate is a practical option if you don't mind freezing your whatsits off. Which is what I'm suggesting but only for rooms that aren't being used. 

It is nuts to heat a room that no-one actually uses - like two of our bedrooms as our sprogs do their own, far more interesting things away from home. These two rooms have not had heating on for over a year now, and only will again when one or t'other crawl back home. Meanwhile, they are both window-cracked-open, and doors shut. This is a 1930's house, so not particularly well insulated, but has few other issues - no water penetration and stuff.

One bedroom has a wall lined with geetars, and they are all fine too. I think. 

 

You are not understanding the basics of thermodynamics. You cannot only ventilate when the internal humidity levels are too high AND the humidity of the external air is also high - there literally is nowhere for the moisture to go in that scenario.

You might get away with it when you also ventilate during the summer and winter months, as across the year the moisture content can be managed in rooms with little use. But this doesn't work in spring/autumn when internal humidity is already high. The ONLY way to provide equilibrium is to heat and ventilate - once the balance is restored, then the heat can be turned off.
There is currently a major source of moisture in the room - that needs to be dealt with before anything else.

An even bigger issue given I am in muggy Manchester. My app frequently suggests that opening the windows will not lower humidity. Although it says the opposite today as it is dry and chilly, so they are wide open and humidity up there is down to 65 at 18 degrees which is similar to the rest of the house.

I don’t have a sense of what the cause for humidity in those rooms is. Actually, I think it is continuous, roughly, across the whole house as even though the downstairs rooms are 5-10% lower humidity they are also kept about 3-5 degrees warmer. So this would suggest that the issue is the attic rooms are closer to the dew point and also that things like sloping ceilings are likely to be the coldest surfaces in the house. So those rooms act like a big dehumidifier in the house, proving a focal point for the moisture created elsewhere to migrate to and condense out. Does that sound wrong?

But if you heated up the attic rooms by 3-5 degrees, then the relative humidity would drop by 5-10%. That is just the relationship between the air temperature and the capacity of the air to hold moisture at that temperature. That doesn't suggest a significant moisture source in the attic rooms, just an acknowledgement that those rooms are cooler than downstairs, and that there's a similar level of moisture throughout the house. The issue is that the surfaces are cold, not that the rooms have high moisture levels.

65% RH at 18 degrees sounds great. But if you aren't heating the attic rooms at all, then the coldest surfaces aren't going to get warmed up at all - as we move into winter, those surfaces will only get colder and increase the risk of surface condensation. Manchester has a very interesting local climate due to its position, so you definitely have higher external air humidity in winter there.

You either need to heat those rooms OR strongly ventilate when it's cold outside. Personally I prefer the heating option as I don't like cold rooms affecting the rest of the house and I don't believe there is much difference in running costs in reality. Turning radiators on in the rooms also warms up the surfaces via radiant heating effect, so works to prevent condensation as well raising the air temperature.

But you also still need (in the short term) to deal with moisture from the recent plastering. It can take up to 12 months for water used in construction to fully come out, although the vast proportion is in the first few weeks. Again I would prefer to run the heating on low to help with this, rather than just ventilating.

WIAWSNB

Aloysius1972 said:

WIAWSNB said:

Aloysius1972 said:

I see the heat vs ventilation debate still rages! In the end condensation control is surely a balance of temperature (air and surface) control, humidity extraction, ventilation and circulation? Can it really be controlled by one of those in isolation?

Yes. But. 

To only ventilate is a practical option if you don't mind freezing your whatsits off. Which is what I'm suggesting but only for rooms that aren't being used. 

It is nuts to heat a room that no-one actually uses - like two of our bedrooms as our sprogs do their own, far more interesting things away from home. These two rooms have not had heating on for over a year now, and only will again when one or t'other crawl back home. Meanwhile, they are both window-cracked-open, and doors shut. This is a 1930's house, so not particularly well insulated, but has few other issues - no water penetration and stuff.

One bedroom has a wall lined with geetars, and they are all fine too. I think. 

 

Does your 30s house have single skin walls, poor insulation etc. I think my 1890s house has very cold surfaces, particularly in the attic space mean that reduced temperature via excess ventilation can bring those down to the dew point quite easily.

Nope, I 'fess. It's double skin with cavity whatsits.
However, without the windows on vent, the panes run with condie - and these are new windows. Windows cracked open, bone dry, even with shivering son overnight.

WIAWSNB

ComicGeek said:

WIAWSNB said:

Aloysius1972 said:

I see the heat vs ventilation debate still rages! In the end condensation control is surely a balance of temperature (air and surface) control, humidity extraction, ventilation and circulation? Can it really be controlled by one of those in isolation?

Yes. But. 

To only ventilate is a practical option if you don't mind freezing your whatsits off. Which is what I'm suggesting but only for rooms that aren't being used. 

It is nuts to heat a room that no-one actually uses - like two of our bedrooms as our sprogs do their own, far more interesting things away from home. These two rooms have not had heating on for over a year now, and only will again when one or t'other crawl back home. Meanwhile, they are both window-cracked-open, and doors shut. This is a 1930's house, so not particularly well insulated, but has few other issues - no water penetration and stuff.

One bedroom has a wall lined with geetars, and they are all fine too. I think. 

 

You are not understanding the basics of thermodynamics. You cannot only ventilate when the internal humidity levels are too high AND the humidity of the external air is also high - there literally is nowhere for the moisture to go in that scenario.

You might get away with it when you also ventilate during the summer and winter months, as across the year the moisture content can be managed in rooms with little use. But this doesn't work in spring/autumn when internal humidity is already high. The ONLY way to provide equilibrium is to heat and ventilate - once the balance is restored, then the heat can be turned off.

There is currently a major source of moisture in the room - that needs to be dealt with before anything else.

I don't even pretend to understand the lot.
All I know is, leave a draught from t'outdoors, and you won't have condie forming. It really is that simple.
Whether it's your garage or porch or bedroom or whatevs, leave a good opening to the outside, and you'll be damp-free.
Assuming there isn't actual ingress from a roof or through the wall.

ian1246

Aloysius1972 said:

Looking at my moisture creation, I am realising that the main culprit is probably my partner’s addiction to our heated airer, drying about 4 or 5 loads of washing per week in a largely unventilated room. That seems to create more moisture than our cooking and bathing combined. 

So I am wondering if I should get a tumble dryer instead. The price of the heat pump models seems to have dropped since I last looked 2/3 years ago and would probably pay for itself vs our heated airer across no more than 4 years based on a saving of about 40-50p per load. That is leaving out of the equation the extra cost from addressing condensation consequences or having to heat more due to opening the window in that room to exit the moisture created.

is that logic sound?

Just get a dehumidifier for around £90.00 Far more economic to run than a tumble drier, doesn't kill your clothes and will dry your clothes in around 24hours.

Aloysius1972

I think the heat pump ones cost around 40p per load and £300 up front so will probably work out cheaper than the dehumidifier after about 2 or 3 years given we do about 5 washes per week.

RedFraggle

We've not used our heated airer since buying a dehumidifier. We bought a meaco and it dries 2 loads overnight in a heartbeat in a single bedroom. 

WIAWSNB

RedFraggle said:

We've not used our heated airer since buying a dehumidifier. We bought a meaco and it dries 2 loads overnight in a heartbeat in a single bedroom. 

What actually dries the clothes, tho'? What room is it in?

ian1246

WIAWSNB said:

RedFraggle said:

We've not used our heated airer since buying a dehumidifier. We bought a meaco and it dries 2 loads overnight in a heartbeat in a single bedroom. 

What actually dries the clothes, tho'? What room is it in?

Much like Red Draggle, I brought a meaco one. I have 2 unheated airers set up in my spare bedroom (3metres by 2.2metres) & i set the dehumidifier to run overnight - the clothes / towels will be dried out within 12-14hours.

It dries the air by sucking moisture out if it. We're talking potentially litres of water needing emptying within a 12hour window - that then means the moisture in the clothes evaporates into the air quicker, due to the air being so dry, drying the clothes. Plus whilst the dehumidifier is working in high humidity, it chucks out a lot of heat - warming the bedroom up significantly, further speeding up how quickly clothes dry.

Energy use is something like a couple of hundred watts an hour, but it has humidity controls so it either switches off (once humidity drops to desired level) or goes onto a reduced power setting as it approaches desired amount, so its energy use is significantly cheaper than tumble driers - particularly since you can dry multiple loads at once (limited by how much space you have for airers in your room!).

My only regret is opting for a 12litre capacity one - should have gone for 20 litre one.

Plus in your situation when your not drying clothes with it, you can use it to start hoovering up excess moisture in your problem rooms!!!

WIAWSNB

ian1246 said:

WIAWSNB said:

RedFraggle said:

We've not used our heated airer since buying a dehumidifier. We bought a meaco and it dries 2 loads overnight in a heartbeat in a single bedroom. 

What actually dries the clothes, tho'? What room is it in?

Much like Red Draggle, I brought a meaco one. I have 2 unheated airers set up in my spare bedroom (3metres by 2.2metres) & i set the dehumidifier to run overnight - the clothes / towels will be dried out within 12-14hours.

It dries the air by sucking moisture out if it. We're talking potentially litres of water needing emptying within a 12hour window - that then means the moisture in the clothes evaporates into the air quicker, due to the air being so dry, drying the clothes. Plus whilst the dehumidifier is working in high humidity, it chucks out a lot of heat - warming the bedroom up significantly, further speeding up how quickly clothes dry.

Energy use is something like a couple of hundred watts an hour, but it has humidity controls so it either switches off (once humidity drops to desired level) or goes onto a reduced power setting as it approaches desired amount, so its energy use is significantly cheaper than tumble driers - particularly since you can dry multiple loads at once (limited by how much space you have for airers in your room!).

My only regret is opting for a 12litre capacity one - should have gone for 20 litre one.

Plus in your situation when your not drying clothes with it, you can use it to start hoovering up excess moisture in your problem rooms!!!

Blimey, that's impressive, and sounds an ideal drying solution.
As you say, all the leccy used by the dehumidifier will ultimately be turned into heat (a tiny fraction into noise), so not wasted.
I'm astonished at how well that works. I'm guessing the clothes will need a final drying on a radiator? 
Sounds good! And no condie in the room? Are the windows fully shut? Any droplets on them?

Emmia

WIAWSNB said:

ian1246 said:

WIAWSNB said:

RedFraggle said:

We've not used our heated airer since buying a dehumidifier. We bought a meaco and it dries 2 loads overnight in a heartbeat in a single bedroom. 

What actually dries the clothes, tho'? What room is it in?

Much like Red Draggle, I brought a meaco one. I have 2 unheated airers set up in my spare bedroom (3metres by 2.2metres) & i set the dehumidifier to run overnight - the clothes / towels will be dried out within 12-14hours.

It dries the air by sucking moisture out if it. We're talking potentially litres of water needing emptying within a 12hour window - that then means the moisture in the clothes evaporates into the air quicker, due to the air being so dry, drying the clothes. Plus whilst the dehumidifier is working in high humidity, it chucks out a lot of heat - warming the bedroom up significantly, further speeding up how quickly clothes dry.

Energy use is something like a couple of hundred watts an hour, but it has humidity controls so it either switches off (once humidity drops to desired level) or goes onto a reduced power setting as it approaches desired amount, so its energy use is significantly cheaper than tumble driers - particularly since you can dry multiple loads at once (limited by how much space you have for airers in your room!).

My only regret is opting for a 12litre capacity one - should have gone for 20 litre one.

Plus in your situation when your not drying clothes with it, you can use it to start hoovering up excess moisture in your problem rooms!!!

Blimey, that's impressive, and sounds an ideal drying solution.
As you say, all the leccy used by the dehumidifier will ultimately be turned into heat (a tiny fraction into noise), so not wasted.
I'm astonished at how well that works. I'm guessing the clothes will need a final drying on a radiator? 
Sounds good! And no condie in the room? Are the windows fully shut? Any droplets on them?

We have a Meaco dehumidifier too, and it dries the clothes. No finishing off on a radiator needed. 

We use ours in a windowless bathroom which has a humidistat fan and the door shut. The room gets fairly cosy  when the dehumidifier is in there working away. 

We also have a washer /dryer and use that for socks and pants. The dehumidifier is great for larger items and knitwear, anything in fact that can't be tumble dried.