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

danlightbulb · Monday at 14:34

Richie said:
Quickie (and possibly theoretical) - If RH reaches 100%, does that mean that the air cannot hold any more moisture and will start dumping it out as water if it gets any higher?

yes correct and that is exactly what condensation is - moisture coming out of the air near a cold surface because the air has more moisture in it than it can hold at its new suddenly lower temperature.

Richie said:
What paragraph are you referring to?

Ha - yes your first one was completely correct.

dlockers · Monday at 14:38

Richie said:
Quickie (and possibly theoretical) - If RH reaches 100%, does that mean that the air cannot hold any more moisture and will start dumping it out as water if it gets any higher?

You're asking if you can create a microclimate/rain cloud in your house? I am also interested in this :cool:

Mason- · Monday at 14:49

dlockers said:
You're asking if you can create a microclimate/rain cloud in your house? I am also interested in this

You effectively do at your cold spots i.e. the windows. You have warm air at e.g. 60-70% RH, rapidly cooling at a window (and the RH therefore increasing) causing condensation.

Sinbad2000 · Monday at 14:53

Richie said:
Quickie (and possibly theoretical) - If RH reaches 100%, does that mean that the air cannot hold any more moisture and will start dumping it out as water if it gets any higher?

You can experience this if you ever do a chamber dive.

When they start releasing the pressure you get the entire inside of the chamber turning into a cloud (both because decreasing pressure and decreasing temperature increase RH)

dlockers · Monday at 14:59

dlockers said:
Seems some are mindlessly chasing numbers reported on their thermostats than any actual benefit.

This is my current situation -

(the (S) sensors are the Hue motion detectors, miles off accuracy).

Looks like the house is "fine" at ~65% but the attic still high. I think I have a hole in the roof from the old F&E tank --- I might stick a dehumidifier up there. It'll all get fixed when we extend/get the loft converted.

^

So as per latest discussion; I don't actually have an issue then? I'm at the top end of recommended but within the tolerance of the sensors probably fine?

Richie · Monday at 16:18

I would say so.

danlightbulb · Monday at 16:18

dlockers said:
You're asking if you can create a microclimate/rain cloud in your house? I am also interested in this

Take a hot shower with no windows open and extractor off. You'll be inside a cloud of near 100% humidity water vapour.

danlightbulb · Monday at 16:21

dlockers said:
^

So as per latest discussion; I don't actually have an issue then? I'm at the top end of recommended but within the tolerance of the sensors probably fine?

Yeah you're lower than me. Solid wall older house will always be worse than new cavity wall house (assuming new house is ventilated).

Any mould spots in corners or behind furniture, especially on external walls?

dlockers · Monday at 18:06

danlightbulb said:
Yeah you're lower than me. Solid wall older house will always be worse than new cavity wall house (assuming new house is ventilated).

Any mould spots in corners or behind furniture, especially on external walls?

Tiny bit on skirting board by the french doors - nothing anywhere else as far as I can tell.

danlightbulb · Monday at 18:16

dlockers said:
Tiny bit on skirting board by the french doors - nothing anywhere else as far as I can tell.

For me, similar, odd spot of mould in the colder areas near doors but nothing major.

And we get condensation on the windows when its cold out.

Its a big improvement on when we moved in, there was a very musty smell to the downstairs. If I go away for a few days and the rooms are closed up, then this comes back in my living room but its better than it was when I moved in.

Just have to keep an eye on it until I can get under the floors properly and see whether I have any water pooling.

jpaul · Monday at 22:00

I'd maybe be checking calibration on some of these humidity measures ..... (earlier post somewhere) had done that on one I picked up for parents ... you put them in a sealed bag with a brine solution.

dlockers · Tuesday at 15:27

jpaul said:
I'd maybe be checking calibration on some of these humidity measures ..... (earlier post somewhere) had done that on one I picked up for parents ... you put them in a sealed bag with a brine solution.

Only practical thing to do is check them against each other tbh

Mysterae_ · Tuesday at 23:23

danlightbulb said:
yes correct and that is exactly what condensation is - moisture coming out of the air near a cold surface because the air has more moisture in it than it can hold at its new suddenly lower temperature.

What the hell is going on in my loft then?!

I've not been up there to check on the upstairs swimming pool that is the loft going by the 99% humidity....

Not long back from work, I'll put my trunks on tomorrow and check it.

danlightbulb · Tuesday at 23:28

Mysterae_ said:
What the hell is going on in my loft then?!

I've not been up there to check on the upstairs swimming pool that is the loft going by the 99% humidity....

Not long back from work, I'll put my trunks on tomorrow and check it.

Nothing is wrong there. The temperature dropped to near zero, so the moisture carrying capacity of the air fell too which is why the relative humidity rose. There won't be much absolute moisture in the air at such low temperatures and it won't be condensing onto colder objects either.

Mysterae_ · Tuesday at 23:38

danlightbulb said:
Nothing is wrong there. The temperature dropped to near zero, so the moisture carrying capacity of the air fell too which is why the relative humidity rose. There won't be much absolute moisture in the air at such low temperatures and it won't be condensing onto colder objects either.

Thanks for the reassurance. There's nothing up there at the moment bar a few tools as I'm not quite finished flooring it. I'm half expecting the new loft flooring to be soaking up any moisture like a sponge.

I placed the humidity sensors at either end of the loft near the apex of the roof, so that may be the worst (or best) place for them to be, dunno. If only the sensors were rated for outdoor use, that would have a useful comparison.

Grim5 · Tuesday at 23:45

danlightbulb said:
Nothing is wrong there. The temperature dropped to near zero, so the moisture carrying capacity of the air fell too which is why the relative humidity rose. There won't be much absolute moisture in the air at such low temperatures and it won't be condensing onto colder objects either.

I was gonna say I thought temp dropping = less moisture in the air, and higher temp = higher moisture carrying potential. If he goes into his loft I wouldn't expect he can feel moisture on his skin

Kol · 2024-11-21T10:50:36+0000

Ever since watching Charlie DIYte and his journey into the humidity rabbit hole I became obsessive about it. In my old Victorian terrace winter was a challenge but our Meaco’s did great.

In our current place, I’ve almost the opposite issue during the cold weather, it’s between 41-45% relative humidity. The dehumidifier clicks on to measure and then clicks straight back off as it’s not needed.