Home > Uncategorized > Clean HRV (air exchanger) filters

Clean HRV (air exchanger) filters

If you have a modern home, you likely have a Heat Recovery Ventilator installed (located in your furnace room).  These are commonly referred to as “air-exchangers”.  When I open these units during my inspections I usually discover that the reusable filters inside have never been cleaned.  Fall is a great time for this chore, so if you have an HRV, put this on your weekend To-Do-List.

VENMAR HRV

First you need to determine whether you are actually running your HRV.  If not, I encourage you to do so.

typical control for HRV

Why do I need to operate my HRV?

Life inside today’s tight homes generates both moisture and pollutants.  The moisture comes from cooking, washing, showers and breathing.  At excessive levels, moisture condenses on windows and also potentially inside your wall structure.  Areas of excessive moisture are breeding grounds for mold, mildew, fungi, dust mites and bacteria.

Combustion appliances also have the potential to allow gases – including carbon monoxide and other pollutants – to escape into the air.  Some common sources include gas ranges and water heaters.

How does an HRV work?

A Heat Recovery Ventilator is a complete whole house ventilation system that incorporates a supply motor and an exhaust motor in one unit.  It is designed to bring a continuous supply of fresh air into the home while exhausting an equal amount of “contaminated air”.  HRVs have a heat recovery core (most are made from polypropylene – while some are made from aluminum).  The core transfers heat from the exhaust air stream to the incoming air stream so you save on energy costs.

air flow inside an actual VENMAR unit

Most units have three reusable filters inside that need to be periodically cleaned.  The instructions below are general guidelines for the most commonly installed systems I find.

How to clean the filters

The block / core filter should be cleaned once per year and the two pre-filters should be cleaned three times per year.

First: Remove the pre-filters and use a dry-vac to clean any loose debris. Then, rinse the filters in a utility sink.

Next, Remove the Solo Core filter. The core filter slides out just like the pre-filters. To clean, fill a utility sink with warm soapy water and soak the filter for at least one hour. After soaking, the filter should be thoroughly rinsed and allowed to dry.

While you’re at it, the condensate tray (located inside the unit & below the filters) should also be cleaned. Use a damp cloth to clean.

The condensate drain hoses can also become dirty / moldy over time, so these should be cleaned, or replaced as needed.

The air intake screen should also be cleaned (I promise this is the last step). This will be located at the house exterior. I usually find that the screen inside this vent opening has become partially clogged with dirt / debris.

screen is commonly clogged with dirt / debris

I found a very good YouTube video that explains this cleaning process in a more detailed, visual way (remember, I said good, not enjoyable).  The video also shows how to remove the interior fan / motor, which does allow for a more thorough cleaning.  Here is the link if you are interested: http://www.youtube.com/watch?v=UUSluMNSjC4

Operating controls for your HRV is a subject for another blog.  For a detailed explanation of user controls for VENMAR units, click here

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Categories: Uncategorized
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