The filters on the PAUL Novus 450 MVHR system were last changed on 1st January (see previous post here). I’d been keeping an eye on them and knew they were going to be ready for a change. I’d already got some spare filters from when I ordered the previous batch.

MVHR Filters after 4 months (01 Jan – 01 May 2017)

It looks like 4 months is about the right interval to change the filters. The more they get blocked the harder the fans have to work to maintain the airflow and the MVHR unit is already costing about £10 a month to run. (I have it on a separate sub-meter which is consistently reporting electricity usage of 65 kWh per month, which I reckon works out at an average of about 80 W.)