# Forum Home Renovation Heating & Cooling  Return air filters: a stark example and a timely warning.

## sundancewfs

Here is the filter pad out of our ducted gas heating system (Brivis Buffalo 85) 
It was installed new, six months ago. 
This gives a good example why a filter pad on the return air vent is a good idea. All this stuff would be blown through the ducts and into the house.
It also shows why maintenance of any filters is very important too. If left, this could create problems for the heating unit by restricting air flow.

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## Moondog55

You collected that in SUMMER?? makes me think you need to rethink you service intervals downward to bi-monthly.
Do you have spares so you can just swap over while that filter is being cleaned and sanitised??
Also is it a single stage filter or is it better ( as in HEPA )

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## sundancewfs

Yep, we use the fan on the Brivis as a re-circulating fan at the moment. It could be argued that we are very messy people and don't clean our house and that is why there is some much dust........Sadly, that is not the case. Although this is no "show" home the house is swept and vacuumed 3-4 times a week and the living area, every day. We don't have any pets either. The reality is, even though we try to take our shoes off at the door, without finished paving outside it can get quite dusty or muddy.
This filter pad is basically a thin piece of polyester batting that was fitted to the back of the return air grill by Paltech. I haven't been able to find an Australian supplier of "proper" return air filters. I even rang 3M yesterday to see if they bring their range in to the country..... but no. So it was off to Amazon.com: Online Shopping for Electronics, Apparel, Computers, Books, DVDs & more to check out price and availability. We ordered two packs of Amazon.com: 3M Filtrete 2200 MPR, 6-Pack, Elite Allergen Reduction Filter, 16 x 20 x 1: Home Improvement filters They are good down to .3 of a micron. Yes Amazon will ship these out of the USA to Australia, and the shipping cost was $24.00 I will have to make a custom filter housing and make a custom grill to suit, but for me, that's easy enough to do. I will still use the poly batting as a pre-filter. And yes Moondog55, I think I'll revise the service schedule on this  :Biggrin:

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## Moondog55

I know EXACTLY what you mean,I am not a fastidious cleaner except in the food prep areas but living in a building site makes for a lot of dust and dirt.
I'll keep that product in mind for when Cecile gets her way and the heater goes in.
BTW - how much does the air circulation help in summer? and is your unit ducted floor or ceiling??

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## sundancewfs

The air circulation works very well in summer. On those days when you just want to keep the house closed up so the heat doesnt get in. it moves air around, through the whole house. although this isn't air-conditioning, it is air movement, and not just localised to a fan. I would have to say, that the fact that it is going through a return air filter is a plus. As I mentioned, all that dust was in the house as airborne particles. Now all nicely collected on the filter.
We will be upgrading our gas central heating (floor duct type) with a high efficiency unit, but will also have the HRV system running too. Our air quality will be a lot better once finished.

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## sundancewfs

An update on the 3M Filtrete 2200 filters..... They arrived from Amazon, I installed on behind the existing poly batting filter and within a week my sneezing and sinus issues had resolved. ( I have chronic sinus problems, with or without a cold) I was talking to a friend of mine about it and they mentioned their sons asthma had been really bad lately, I gave them one of the filters to try and they were very suprized when, within a week, he was sleeping through the night and not waking up wheezing and coughing. Anecdotal evidence, yes, but a good result I think.

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## Moondog55

Thanx very much for the update sundance; makes me rethink the size of the first box for our air transfer system.
How do you clean the 3M filter?? 
How much was shipping? as the cost .benefit ratio appears huge?

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## sundancewfs

Moondog55 Have a look at the link to Amazon on an earlier post  :Arrow Up: 
There are many different sized filters available ( and filtration levels) I chose these ones because they were closest to the return air filter size I currently have and the highest filtration level 3M make. The shipping for 2x6 packs was $24.00US and it took about 2 weeks. Oh and they are designed to be disposable. That's one of the reasons I'm still using the existing batting filter pad as a pre-filter so as to extend their live a bit.

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## Moondog55

So what do you reckon will be their working life?
Saves me looking at 3Ms website.
 would agree that using a prefilter is smart and it is what we would do, even to using 2 prefilter layer of different screen sizes
Price isn't exorbitant neither is postage

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## sundancewfs

They reccommend 3months. The cost of a 6 pack is $120US plus the shipping

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## Moondog55

So what do you reckon will be their working life?
Saves me looking at 3Ms website.
 would agree that using a pre-filter is smart and it is what we would do, even to using 2 pre-filter layer of different screen sizes
Price isn't exorbitant neither is postage

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## ozheat

Just watch out that you aren't putting too much of a restriction on the airflow or your heater will trip out with overheating problems.
Return air grill sizes are enlarged 20-30% when a filter is used.
Regular polyester filter media is available at most heating or airconditioning suppliers.
I have a couple of 5-10 micron filter material 100m rolls in the garage if you are intrested in a lot cheaper alternative to the 3m stuff.
Also those 3m filters are designed to be used with an elecrostatic filer unit, which is esentially a negative ion generator with a charged mesh grille in front of the filter.

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## sundancewfs

Any time someone can point us towards local suppliers of products that are of equivalent rating and quality is welcomed. I used 3M filters in my central heating in Chicago, it did not have an electrostatic filter unit. The media of the filter is electrostatically charged, much the same as a swiffer or glitz dusting cloth. One of the points made by the reviewers of the 3M Filtrete 2200 on Amazon was that it was much more effective than filters which filter out only larger particles. There is a LOT of difference between 5 micron and .3 micron.

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## Moondog55

> Just watch out that you aren't putting too much of a restriction on the airflow or your heater will trip out with overheating problems.
> Return air grill sizes are enlarged 20-30% when a filter is used.
> Regular polyester filter media is available at most heating or airconditioning suppliers.
> I have a couple of 5-10 micron filter material 100m rolls in the garage if you are intrested in a lot cheaper alternative to the 3m stuff.
> Also those 3m filters are designed to be used with an elecrostatic filer unit, which is esentially a negative ion generator with a charged mesh grille in front of the filter.

  That is a point I will keep in mind when I build the box for the first take off point, but I'd be happy to buy a few meters of the poly from you for the prefilter, I find polyester much more robust than the foam usually sold as filter media

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## ozheat

Moondog55,
PM me your address and I'll send you a couple of meters or what ever will fit in an A4 enevelope in the post.
The filter material isn't polyester or foam but is a unwoven cloth type material, its main use is in office climate control systems.

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## Moondog55

Many thanx PM sent
Probably the polypropylene fabric also use as geocloth and a a base for waterproofing bathrooms, cool stuff

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## sundancewfs

I thought seeing as this thread has got new life, it was time to clean the filter again....
I posted the original pics on the 9th of May 2011 and today is 5th of July 2011, so close enough to 2 months.   
On the the 30th of May (not April) I put in the 3M Filtrete 2200 filter ( I wrote the wrong month on the "install date" sticker) the filter was placed in the air return box over the intake hole. As you can see from the pic, the hole is smaller than the filter. This has lead to the area covering the hole filtering the dust and leaving a clean area where the filter was not subjected to the air stream. This is a good example of how much dust gets through the standard filter, which is still used in its original position as a pre-filter for the 3M filter.

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