I’m very interested in a system like drimaster to help with home humidity as mentioned by a few on here.

A quick question, its been wet and warm recently – my outdoor monitor has been showing humidity around 80-90% indoors around 60-70 (maxed at 82)

Now if I buy something like a drimaster, I believe it pushes air from the loft into the house to help push out home created moisture, but, what happens if the air outside is humid already, and more humid than the home? Does it not work in this scenario?

The humidity will change in the house dependant on the outside humidity (ours certainly does), but the humidity is still lower than it would have been previous by 15-20% for the given conditions.

The whole thing about pushing the moisture out is in the title ie positive pressure, and therefore so long as the pressure is greater inside the house, it will continue to force out. (I guess in theory)

I think what is most important is having the dry stable air in the loft. If you don’t have that the system wont work. For that you need ventilation in the loft, but not too much !

At times where the temperature is similar inside and outside then pulling more humid air inside doesn’t matter that much because it won’t condense as the normal surfaces like windows and walls aren’t any colder.

At times where outside is colder the system works by the fact that warm air can hold a lot more water; cold and damp air outside will reduce in relative humidity as it warms up inside. I can’t remember the exact numbers but it’s something like air at 7 deg C, 95% humidity will reduce to 45% humidity when warmed up to 20 deg C. Overall the inside humidity will decrease, and while the air is initially colder dry air takes a lot less energy to warm up, so it may be more efficient than just trapping the warm but damp air inside.

loft should be sufficient (just tiled no felt)

So it is relative humidity which is why outdoors looks worse (it’s colder)

Did anyone go for the heater model? My house is already big and drafty so worried about it making it too cold, thpugh take the point drier air heats easier.

looks like I’m just going to have to take a punt

yes. heater model. wired it up as standard. no idea how often it ‘heats’ but i’ve not noticed any negative impact on electricity bills.

it is noticeably cooler in the hallway where the vent vents but not in a bad way.

Heater here too but never used it…