I thought I mostly knew about dehumidifiers, but it seems every day is, as they say, a school day.
Admittedly the realisation that these things have a COP and put out more heat than they consume in electrical power produced a forehead slap and an “of course they do” moment - they are, essentially, the reverse of the process by which evaporative coolers cool after all and give you back the latent heat of vaporisation of any water that they collect.
I quite like Alec’s videos, almost always interesting and he has a very easy style which hides a lot of information.
As noted towards the end of the video refrigerant dehumidifiers do not work well at an ambient of 13°C or lower as the evaporator tends to freeze up. Dessicant dehumidifiers are much better and will work down to, or even below, freezing - though you have to remember that air around those temps can’t hold much water vapour anyway.
They don’t use a refrigerant cycle though so are much less efficient.
We use a refrigerent dehum in our bathroom which doubles as a clothes drying room rather than a tumble dryer. The additional heat output from the unit helps release water vapour from the clothes so it can be collected in the unit. Its a smaller room so we can raise the ambient in most cases. Over in France, downstairs windows are still single glazed so with a form of heat on and cold outside temps, water vapour condenses on the glass, we remove that with a window vac quick and effective.
Picked up one of these a few weeks back on Amazon… this one to be precise. It has a tube to allow it to evacuate water down a drain but also has a 3L reservoir that needs to be emptied manually. The layout of our house means we have to use the reservoir… It fills up daily which was absolutely eye opening for me
Thats 1 solution the extract fan in the shower room was a regarded British make and the humidity sensor was quite enclosed and at the end of a cul de sac so to speak and humid air would simply pass by rather than reach the sensor so never really worked that well. I cut out lots of unecessary plastic to allow the extract fan to draw air across the sensor which improved things but still not as I wanted as you cannot set start and stop humidity. I purchased a humidity switch from AliExpress and now it works perfectly, on at 73%Rh off at 60. The humidity sensor has a 1m cable so can be placed in a good spot for sensing.
To my slight chagrin I own five dehumidifiers - two dessicant units and three refrigerant ones (the ProBreeze 12l/day which is pretty much the same as in the video).
Still trying to get on top of mould problems chez nous which started during Covid when we could only get over about twice a year for 2020 and 2021 (and that took some effort), it wasn’t just lack of “airing” the property though - looking at rainfall records the last 4 years have been much wetter than the previous 5 (we’ve had the house 10 years now) and there have been additional “water related” problems such as the cellar flooding.
Slowly winning on that one but leaving a dehumidifier running, for all the expense, has been more reliable than leaving the VMCs running.
One thing about desiccant dryers is that they will get the air really dry - down to 5% or less in a semi-closed environment. I use dehumidifiers for certain processes, and the bigger jobs also draw upward of a continuous 3kw, which in turn requires industrial plugs and sockets.
The other day I picked up a passive dehumidifier, might be a piece of junk but will give it a try. Fortunately we do not suffer like we used to but its still a little more humid when we arrive after its been closed for a while so just a little experiment.
Is that a dot and dab plaster board wall in the picture?
But, as far as I know it’s plaque doublage, though it probably is dabbed between the polystyrene and the wall behind.
The windows recesses (and door, which you can see the other side of the radiator in the first shot) are most prone to condensation because they are relatively cold.
Thats normal for reveals to be the cold spots, even in new builds the problem exists if humidity gets high. A few Asians on one development like the heat and used to high humidity I had to explain that in the UK’s cooler climate they would get mold unless they left the heat recovery ventilation unit.
the extract fan in the shower room was a regarded British make and the humidity sensor was quite enclosed and at the end of a cul de sac so to speak and humid air would simply pass by rather than reach the sensor so never really worked that well. I cut out lots of unecessary plastic to allow the extract fan to draw air across the sensor which improved things but still not as I wanted as you cannot set start and stop humidity. I purchased a humidity switch from AliExpress and now it works perfectly, on at 73%Rh off at 60. The humidity sensor has a 1m cable so can be placed in a good spot for sensing.
