Filter ideas - basement fan

[cawright1]

Hi all.

I live in a late Victorian terraced house and have developed my basement into an office area, and I spend a lot of time down there working on various projects. OVer the past few months or so I've become a bit wheezy with my throat etc, and after a chat with the doc, it looks like my problem could lie with the extractor fan in the basement. The fan is on street level, and we live on a main road. Therefore, the stuff coming through the fan all day long is vehicle emissions, patently, not good for the old lungs. Now, I could just put something over the fan to keep the stuff out, but, then I'd have no air at all coming in, so, looking for any filter ideas if possible. Maybe there already is a solution for this as many people these days are doing up theeir basements? Any help appreciated.

 

[Moo]

We live in a terraced house on a busy main thoroughfare too, and we have a sizeable basement/cellar, but no problem at all with traffic fumes.
This is, perhaps, because we've sealed the windows shut and keep the door at the top of the cellar steps open all the time (except on the rare occasions when a small child is visiting us).

Have you considered relocating the air extractor so that it sucks in air from the house rather than the street?

 

[Flyfisher]

Or, to implement Moo's suggestion in a slightly different form, can you not just reverse the operation of the fan so that it blows your basement air into the street. Unless your basement is completely sealed (unlikely) then this should draw air into your basement from the house, which hopefully will be less polluted.

 

[MdB]

... which hopefully will be less polluted.

And warmer!

The downside with this method is it is also likely to be damper. As the basement is likely to colder than the rest of the house, this could be a recipy for condensation.

 

[cawright1]

To be honest, I rarely switch the fan on to use a 'blower'. It's use is more to allow the trickle of air in from the outside. So, some kind of filter would definitely help.

 

[chuckey]

Filters are a science, it all depends on what is effecting you. It is possible to get filters that stop micron sized particle but the downside is they are expensive, get blocked with larger particles quickly, and require a powerful fan to get any air through what so ever. So the thing to do is to experiment with various filter media until you get the desired effect.
As an initial step I would suggest a replacement filter paper for a cooker hood, tape it over the air duct and see what happens, one thing is certain the air flow will reduce. If this does the trick the job really comes down to building a picture frame to hold it with criss cross bars to stop it billowing/falling out.
Another cheapo filter media is called 1/2" 1" foam as used for upholstering furniture, its quite cheap (£2 for 3' X 2'), install in above picture frame.
Another more expensive option is one or more filters for a wet and dry vacuum cleaner(see :- http://www.screwfix.com/search.do;jsessionid=X0ZO0V5G3UPXQCSTHZOSFEY?_dyncharset=UTF-8&fh_search=filter&searchbutton.x=6&searchbutton.y=9 for a variety), these are more difficult to install but may work better.
Air can only get into your basement, if it can get out again other wise your basement will inflate and explode.
Frank

 

[Penners]

This may be a very stupid observation (others more expert than me - please feel free to comment!), but I'm not sure that a filter is going to be the answer to your problem.

Aside from diesel particulates, I understand that the majority of traffic fumes are gases - carbon dioxide, sulphur dioxide, carbon monoxide, etc. OK, catalytic converters have greatly reduced the noxious elements in recent years, but they do still exist. So, unless you install a sophisticated gas "scrubber" system, I don't think that a plain filter will have much effect on these.

If I had to deal with your problem, I think I would be trying to source the imported air from elsewhere. Either, as Moo suggests, from inside the house, or ducted from the back or from much higher up the building.

 

[Onetap]

It sounds like asthma (IANAD). Animal allergies? Any other sources of dust or fumes? Sawdust, unsealed glass/mineral fibre insulation, industrial processes, paint, solid fuel fires, candles, agricultural spraying, air freshener aerosols?

Axial flow fans (like Vent-axia extract fans, computer fans, etc) are good for high volume at low resistance, but the performance of most drops off fairly dramatically if you put some resistance (ducting, filters) into the air path. Pads of filter media are fairly rubbish, you'd need a pleated panel filter (look at a car pollen filter).

If it's an extract fan, it should be blowing air out. If it's blowing air out, pollutants won't be coming in through the fan. If there's an extract fan, where does the supply air come from?
Suggestions;

a whole house heat recovery system, with the filtered air intake at the top/back of the house. You'd need a ducted extract run back to the extract fan from the basement.

Look at air cleaner systems; search for air cleaners in the House & Home section of E-Bay. This will bring up air cleaners mostly on the US site. They just recirculate the air, hopefully taking most of the dust out. I believe the Honeywell ones are good, but I've no first hand knowledge.

Go and rip the ventilation system out of a scrapped car, complete with pollen filters and 12V fan. Use that to supply filtered air from the house. Run the extract fan as well.

Beyond that, you're looking at a mini ventilation system (like the car system, but purpose built and serious money). Google for mini AHUs.