Humidity in house

Author
Discussion

rufusgti

Original Poster:

2,528 posts

191 months

Tuesday 1st December 2015
quotequote all
I purchased a humidity gauge a week or so ago as I'm always getting condensation on the Windows inside. I'm getting readings of between 55-70% depending on the temperature, cooking, baths/showers etc etc. This seemed a bit high from reading around online so plugged in a dehumidifier. It's been running for about 24 hours and collected about 2 litres of water so it's doing its job. I set it to 55% to help keep it a bit lower. Today however I'm still getting readings of 60-63%.

I''m wondering what is actually a likely figure to be reaching on a wet day in December in Wales. I was shocked to find that the forecast for today was 80% and tomorrow 90%. Now I'm wondering if I'm being a bit optimistic at reaching 55% in a 1940's 3 bed semi at this time of year.

Any views or advice welcome.

It's fixable...

468 posts

204 months

Tuesday 1st December 2015
quotequote all
The first question you should be asking yourself is whether you have a problem with the humidity as it is?

Any mould, damp patches and other stuff like that?

If no and you just have squeegee of your windows and dry the cills then you haven't actually really got a problem.

If yes then the first thing you need to do is assess how your house is breathing - is there to little or too much ventilation. Are you drawing in damp air or are your habits in the house generating the problem. Just blocking everything up and turning the heating up doesn't solve the problem.

rufusgti

Original Poster:

2,528 posts

191 months

Tuesday 1st December 2015
quotequote all
I don't think I have a problem as such. There's no mould growth except on the windows if I don't wipe them down once a week. But I was led to believe 60+ is on the high side. We have a good quality powerful bathroom fan and we open the windows in the mornings. Keep the place warm and have a log burner. But 4 people, cooking, washing, laundry creates moisture. Just wondering if it's worth keeping the dehumidifier pumping away trying to reach 60% when it's 80% outside.

V8RX7

26,766 posts

262 months

Tuesday 1st December 2015
quotequote all
Humidity meters are very crude IME.

I have an Ebac I leave on Auto which removes around 5l every few days at the minute.

I'm a great fan of having no drafts and then I open windows on nice days.

The theory is that the dry air takes less heat to warm so it shouldn't cost anything to run.


moles

1,794 posts

243 months

Tuesday 1st December 2015
quotequote all
Trouble with dehumidifier is unless the house is airtight then on a wet day every time you open a door you let a massive amount of damp air in that the unit then spends the rest of the day removing. I have started to turn mine off on damp days as it pulls out 5-8 litres a day but all I'm doing is drying the outside air. On a normal dry day the humidity in our 300 year old house is 55-65% on a damp day this shoots up to 70-80%.

Simpo Two

85,149 posts

264 months

Tuesday 1st December 2015
quotequote all
Open a window smile

sparkythecat

7,898 posts

254 months

Tuesday 1st December 2015
quotequote all
OP, you may find the recommendations here help.
http://www.telegraph.co.uk/finance/property/advice...

Ug_lee

2,223 posts

210 months

Wednesday 2nd December 2015
quotequote all
Steady constant heat seems to have worked for me. House is near 200 years old and dehumidifier was initially pulling 10-15l a day and humidity of 70% and above.

I know I'll never get the house as warm as modern houses but have it set st a constant 18.5deg. After 3 months of constant emptying of the dehumidifier it eventually tapered off until it's hardly on at all.

Now between 55-60% everything seems fine now.

TA14

12,722 posts

257 months

Wednesday 2nd December 2015
quotequote all
It's fixable... said:
the first thing you need to do is assess how your house is breathing - is there to little or too much ventilation. Are you drawing in damp air or are your habits in the house generating the problem. Just blocking everything up and turning the heating up doesn't solve the problem.
The heat/ventilation amounts and balance are key. A typical well maintained 1940s semi with good loft insulation and double glazing should not have a problem with condensation.

Sheepshanks

32,531 posts

118 months

Wednesday 2nd December 2015
quotequote all
rufusgti said:
Just wondering if it's worth keeping the dehumidifier pumping away trying to reach 60% when it's 80% outside.
Key thing - the number you're seeing is RELATIVE humidity.

Ignoring everything else, if you bring that 80% RH / 10C air into the house and warm it up to 20C its RH will drop to 40%.

CaptainSensib1e

1,432 posts

220 months

Wednesday 2nd December 2015
quotequote all
I don't know if this is relevant or not, but its been very wet recently, so surely there must just be a lot of general moisture in the air (both inside and out).

Unless you have an obvious damp problem, I can't imagine its anything to worry about.