Humidity in the House....Talk to me!

danlightbulb said:
Yeah to this day the first thing my mom does every day is all windows in house wide open. Doesn't matter how cold it is outside. Open for a good hour then closed up and house reheated.
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Once a week I will do this - open all windows for about 30 mins or so and allow an exchange of air. Daily, I will open thw windows of any bedrooms that were used that night, as well as the bathroom, to let any humidity out asd its amazing how much moisture the human body can release while sleeping in a sealed room for 7-8 hours.

Although I doubt its accuracy, my Nest thermostats are reading 62% for the living room and 65% for the main bedroom humidity right now so not too bad.
 
dlockers said:
I feel like this is a bit con from big-dehumidifier. I don't remember my parents fretting about this nonsense nor having a billion relatively-expensive sensors dotted around :cry:
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Certainly when I was a youngster we had metal frame single pane windows, drafts all over the place, no central heating and a fire in the lounge, things have certainly moved on.

The problem with modern living is homes are too warm and have no ventilation, plus squeezing more people into smaller and smaller spaces.
 
Here's an example of what's wrong with my house, measurements taken just now.

There's only me in the house and Im not doing anything aside from sitting at my laptop. Windows and doors are all shut (but there are a lot of airbricks in my house so should be plenty of ventilation).

Inside temperature a steady 19.7 C, humidity 69%.

Outside 13.3 C, humidity 74%.

According to this calculator, 13.3 C and 74%, heated to 19.7 C, should give a RH of 49.6%. So I am 20% higher than what should be the case.

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That is a hell of a difference. Where is the moisture coming from? Its been fairly dry for a week now outside, I don't believe its coming from the air outside. Its something else.
 
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danlightbulb said:
Here's an example of what's wrong with my house, measurements taken just now.

There's only me in the house and Im not doing anything aside from sitting at my laptop. Windows and doors are all shut (but there are a lot of airbricks in my house so should be plenty of ventilation).

Inside temperature a steady 19.7 C, humidity 69%.

Outside 13.3 C, humidity 74%.

According to this calculator, 13.3 C and 74%, heated to 19.7 C, should give a RH of 49.6%. So I am 20% higher than what should be the case.

image.png




That is a hell of a difference. Where is the moisture coming from? Its been fairly dry for a week now outside, I don't believe its coming from the air outside. Its something else.
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There may be airbricks, but there's also been very little wind so how much air transfer has there been realistically over the past few days?
The humidity comes from you - you breathe out water vapour, you perspire a little... cup of tea perhaps? (as well as any retained moisture from any porous surfaces inside).
 
Sinbad2000 said:
There may be airbricks, but there's also been very little wind so how much air transfer has there been realistically over the past few days?
The humidity comes from you - you breathe out water vapour, you perspire a little... cup of tea perhaps? (as well as any retained moisture from any porous surfaces inside).
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The dehumidifier has also been on overnight (off since this morning). Its also been on the past few days. Any retained moisture should be being pulled out of the fabric of the house by the prolonged use of the dehumidifier, but its not touching it as you can see from these figures.
 
I would also cross check with a known-good calibrated hygrometer. They can be notoriously inaccurate. When I kept cigar humidors, it wasn't uncommon for good hygrometers to drift out by as much as 20% in a short time.

Even if it is accurate outside, it does not mean it is accurate in the ranges that exist in your house.
 
danlightbulb said:
Ok Ive ordered 3x Govee bluetooth units from Amazon. I'll see how closely they match the simple display I currently have, then I'll put one outside and two in the house and start tracking properly.
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I’m interested to see your results. I love experiments like this. Must be getting old :D
 
I have 3 hygrometers at upstairs, they are all within a couple of percent of each other, and then there is the one built into the dehumidifier. That makes 4.

I also have a 5th one which is not open in a box (just a sensor, need app), and a 6th one which is part of my security camera.

I think I have enough to get a good average lol
 
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Raymond Lin said:
I have 3 hygrometers at upstairs, they are all within a couple of percent of each other, and then there is the one built into the dehumidifier. That makes 4.

I also have a 5th one which is not open in a box (just a sensor, need app), and a 6th one which is part of my security camera.

I think I have enough to get a good average lol
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Precision isn't accuracy though. You are better off buying a decent one and then doing a two point salt calibration using something like sodium chloride to get a reading at ~75% and magnesium chloride to get a reading at ~33% to see if your kit is accurate.
 
if its mainly for the guitars then I would put it in the room where the guitars are and close the door. If you want the house then leave the doors open and leave it on the landing and let it run in the background. Personally I would only run it at night to save money. Remember after a shower, close the bathroom door and leave extractor fan running for at least 10mins.
 
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We have a couple of dehumidifiers that do the job. No more condensation.

dlockers said:
I feel like this is a bit con from big-dehumidifier. I don't remember my parents fretting about this nonsense nor having a billion relatively-expensive sensors dotted around :cry:
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Our house growing up was incredibly drafty, you could hear the wind blowing through it, especially with all the chimneys. New houses are sealed tight.
 
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My three Govee humidity sensors arrived yesterday. Seem decent, all three are close to each other on the readings and fairly close to my older cheapo unit.

I put one outside, now reading 9 degrees and 94%, and I put one downstairs and one in the bedroom. Both of those are reading low 70's humidity at 17 degrees.
 
Now that the loft is sealed with the exception of the pathetic soffit vents the roofers put in when I had them replace the facias etc, the humidity in the loft is quite alarming:

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I presume that now the average overnight temperatures are dropping near or to the dew point, I'm expecting moisture to start building up in the loft:

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Looks like I have no other option but to get a (different) roofer in to install some roof vents to improve the airflow in the loft.
 
Mysterae_ said:
:confused:
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You said “get a roofer to ventilate it” in the hope it will help.

He is saying “look outside, it can’t get more ventilated and it’ll still have moss and mould when wet”

My theory is that the warm air from your home is getting through the ceiling in your house to the roof and it’s trapped there. Ventilation will help, both in summer and winter, but I would look into whether you are getting condensation in the roof. If it’s dry on the walls and beams then it will be fine. If it’s wet then it’s time to do something.
 
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