Cellar ventilation advice.

Maclaverty

I have a converted cellar and have been using an air purifier for air movement and a dehumidifier for 4hrs a day to keep it dry. Have had a few issues with moisture and mold along the carpet line but nothing substantial over the 3 years we have lived in the house.

I am trying ways to stop using the dehumidifier as getting a tad bored of emptying it every 3 days and having to use a 20ltr bucket when going on holiday for it to drain into. There is a small window in the corner and an air brick in the other and have tried to simply leave the window open and switched off the dehumidifier for a 2 week period to see if that's enough to keep it dry but had a massive mold outbreak after the 2 weeks so window closed and dehumidifier back on.

Thinking of getting an extractor system placed in the far corner as the wall is external and backs onto a pit on the other side. 

The room is 5m by 4m so would an extractor in the far corner be powerful enough to extract the air from the entire room or would It just extract the air closest to the corner? Was looking at a continuous DMEV system to constantly extract stale air and bring in fresh air through the air brick.

But, I am wary about drilling a hole through the cellar and potentially disrupting the equilibrium of the cellar and unsure whether to just keep the dehumidifier running and deal with the upkeep.

casper_gutman

Where would the extractor be relative to the air brick? If they're in opposite corners then there should be a decent effect on the overall humidity of the air in the cellar. If they're right next to each other, this is suboptimal as the air can be sucked in through the air brick and head straight out again without much of the room seeing any effect.

Maclaverty

yes the air brick is on the opposite corner, right by the stairwell. The extractor fan will be on the far corner. Does a dehumidifier do a similar job or always better to get mechanical ventiallation? I also have a small window on the opposite side of the room and unsure whether leaving it on a latch would create air flow through the cellar or would it not be enough?

casper_gutman

There are pros and cons to both dehumidifiers and mechanical ventilation, depending on the situation. If the cellar is pretty much unheated and used mainly for storage, then relatively high-flow ventilation may be effective (and cost effective) relative to dehumidifiers which kick out a fair bit of heat (depending on the technology used) which could be unneeded and/or actively unpleasant in summer. If it's a space you're trying to heat and occupy then ventilation a high flow of outside air might be unwanted as it'll bring more cold air into the house - even if it's an extractor fan and the replacement air is drawn from the upper floors of the house, cold outside air will be coming in somewhere to replace it as your house isn't completely airtight.