How to address my humidity issues

WIAWSNB

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. 

 

WIAWSNB

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?

Yes, no, maybe.

Is this a dedicated room for the air dryer? Does it have windows? How many?

If so, open the windows as far as you can, 'shut that door', and air-dry away. 

Don't let this extra moisture get into the rest of the house, but ventilate it away oot t'windows instead. 

To add to what I said before, I currently have two unheated bedrooms which are bone dry. The windows in each are set to 'vent'. If I fling open the windows fully, then I'd not only freeze in there, but could possibly be flushed out a window by a particularly strong gust. 

But...my parting memory would be a proud one of a bone-dry room. A sacrifice worth making.

Aloysius1972

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.

ComicGeek

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.

ComicGeek

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. 

We use a heated airer frequently, but we have one with a cover. This significantly reduces the amount moisture released into the air and reduces drying time. We put ours in the kitchen which is well ventilated anyway - I open a window slightly if I put it in any other room, and that's sufficient with the airer cover on.

shiraz99

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.

I think you're slightly confusing the term single skin walls to solid brick walls which I guess is what you probably mean, but yes, the majority of houses of that age and older will still be solid brick construction as cavity wall built homes were still in their infancy.

ComicGeek

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?

No, it can't be controlled by one in isolation.

You need to heat up the room air so that it can absorb more moisture - you then need to extract that moist, warm air to outside (or strip out the moisture with a dehumidifier) and replace with dryer, cooler air. Then you heat up this air so that it can absorb more moisture, and repeat. If you have a regular source of moisture into a room then you will be repeating this constantly - if it's a one-off event (like a shower or airer) then this is only needed until the moisture is dealt with.

The relationship between air and surface temperature will determine the amount of ventilation needed to control surface condensation. Swimming pools have the air temperature very similar to the pool water temperature to combat condensation, as an extreme example.

Aloysius1972

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?

This also leaves me to think my big single glazed bay windows downstairs are a blessing in disguise. They can get half a litre or more condensation on each of them on a winter morning which I vacuum off with my Karcher to no ill effect really. I assume if I had double glazed those windows that same moisture would like get attracted to the next coldest surfaces which are mouldy walls - much worse.

Aloysius1972

ComicGeek 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?

No, it can't be controlled by one in isolation.

You need to heat up the room air so that it can absorb more moisture - you then need to extract that moist, warm air to outside (or strip out the moisture with a dehumidifier) and replace with dryer, cooler air. Then you heat up this air so that it can absorb more moisture, and repeat. If you have a regular source of moisture into a room then you will be repeating this constantly - if it's a one-off event (like a shower or airer) then this is only needed until the moisture is dealt with.

The relationship between air and surface temperature will determine the amount of ventilation needed to control surface condensation. Swimming pools have the air temperature very similar to the pool water temperature to combat condensation, as an extreme example.

Thank you. Is the principle of the set up I have been quoted for - a PIV pushing (mostly) dryer cooler air in from the loft accompanied by an extraction unit in the ground floor kitchen diner - consistent with this principle and would enhance the air replacement ‘cycle’? Similar to creating a through draft by opening windows in each end of the house. Alongside some background heating to mitigate the residual risk of cold spots in the house.

Aloysius1972

shiraz99 said:

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.

I think you're slightly confusing the term single skin walls to solid brick walls which I guess is what you probably mean, but yes, the majority of houses of that age and older will still be solid brick construction as cavity wall built homes were still in their infancy.

Apologies, I was. I meant solid brick walls.