So this is a student house about 20 years old, loft is well insulated but the room is on the north side of the house. LL is fed up of complaints about mould and redecorating..... I appreciate that for the majority of residents this would not happen, they are probably drying clothes and not running the heating but I have to sort. Fortunately the builders left two vented roof tiles which never appear to have been connected to the two upstairs bathrooms, these only have axial fans which will not shift air over the distances required. One bathroom works well as the fan has no ducting at all and just discharges into the loft! the other has ducting to a side wall but ageing is not working efficiently. So the plan is to put in three mixed flow fans, the 2 bathrooms will be connected to existing wiring and the via the roof vents. The problem comes for the north facing bedroom and how to control the fan. Timer, humidistat, constant low speed or PIR? These can shift a lot of air so I don’t want to remove all the heat from the room and humidistats is tempting but they are not particularly accurate (?) and I don’t want to leave things that can be fiddled with! I had considered a centrifugal fan with humidistat but it’s about a 5 metre run with a vertical lift and I don’t think it wI’ll be powerful enough. Your thoughts please!
You may find a better solution is a mult-room extraction system like the ones here: https://www.fastlec.co.uk/ventilation-extractor-fans-monsoon-domestic-fans-multi-room-extractor-fans The issue with an individual fan per room is the actual switching on/off of the fan. Students hate spending money on anything other than booze. They will look for ways of avoiding having the fan switch on at all. The multi-room solution sits out of reach of the meddling student fingers and runs all the time on a trickle basis, automatically adjusting if the humidistat senses it needs to.
Thanks Unphased and apologies for the slow thank you! Bit of a domestic crisis withe the MIL!! Wow these are expensive I have decided to go for a simple timer and switch it on maybe 4-6 times a day for short periods.