Reuben's Home Inspection Blog


HRVs, Part 2 of 3: Maintenance & Operation

Last week I blogged about why houses need HRVs.  This week I'll write about maintenance and operation of HRVs, and I'll try to cover the stuff you should know if you own one.  The information in this blog is general - every manufacturer will have their own set of instructions and their own maintenance schedule.


  • Every three to six months the filters should be cleaned by vacuuming to remove as much dust as possible, then washed with warm water and mild soap.  Some filters can also be washed in the top tray of a dishwasher, but this may tarnish the aluminum finish.  The filter below should have been cleaned a long, long time ago, and this is what I find at almost every home inspection - way more than dirty furnace filters!

 Dirty HRV Filter 
  • Every three to six months  Clean the condensation tray with damp cloth.  The condensation tray is the area where water will collect in the bottom. The condensate drain should be checked, and replaced if needed.  The drain tube usually consists of clear plastic tubing with a little loop that creates a trap to prevent odors from the floor drain or wherever else from getting sucked in to the HRV.

   HRV Basics 
  • Every three to six months  Check the intake grill at the exterior of the home to make sure it's clean.  These get very dirty, as there is a fan constantly pulling air in.

Dirty HRV Intake 
  • Every six to twelve months the core should be cleaned by removing it and letting it soak in a mixture of lukewarm water and mild soap.  Rinse the core thoroughly when done.  If you own a summer core, don't get it wet, as you'll cause permanent damage to it.  Summer cores can be cleaned by vacuuming with a brush attachment.

 HRV Core 
  • Every one to three years the fans should be cleaned.  This typically requires removal of the fan assembly.  Check the owner's manual for specific instructions, or hire a professional to do this.



Operating an HRV is usually quite simple.  If the HRV has a switch located on the unit itself, it will typically have a couple of the following settings, but not all:  On, High, Low, Off, or Remote.  If your HRV has a "Remote" setting, you'll probably want to use that one. This will allow the HRV remote controller, usually mounted on the wall next to the thermostat,  to turn the HRV on and off.  This remote will also typically have a dehumidistat, which controls how much moisture is in the air.

If the bathrooms in the house have funny little wall buttons instead of bathroom exhaust fan switches, it typically means that the HRV system has had ductwork installed in the bathrooms.  This is an acceptable alternative to bathroom exhaust fans.  When the wall button is pushed, this will turn on the HRV for somewhere between 15 - 60 minutes, or will kick the HRV in to high gear for 15 - 60 minutes.

Every HRV should also have a defrost cycle, and the HRV should go in to the defrost cycle automatically when it gets too cold.  The defrost cycle is actually quite simple; the exhaust fan just runs for about five minutes, which forces a bunch of warm indoor air through the core without bringing in any cold air.

If you plan to operate your HRV during the summer, check your owner's manual to see what the manufacturer has to say about it.  If your HRV is designed to run during the summer, you'll probably need to remove the standard winter core and install a summer core.  The difference is that the summer core is designed to remove moisture from the air coming IN to the house, rather than the air leaving.  If there is no mention in your owners manual about running your HRV during the summer, you probably shouldn't.  

That's about all for maintenance - for any more specific instructions, you'll need to check your owner's manual.  Next week I'll talk about installation defects.


Reuben Saltzman, Structure Tech Home Inspections


Comment balloon 6 commentsReuben Saltzman • December 22 2009 08:07AM


Reuben, another great post----I think people forget these filters and air intakes----they need alarms on them:)

Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) over 10 years ago

Man that filter is disgusting! Great post and info.

Posted by James Quarello, Connecticut Home Inspector (JRV Home Inspection Services, LLC) over 10 years ago

Charles - no doubt!  I'm almost glad I don't have an HRV at my own house.  With all the dirty HRV filters I see, I'm pretty sure I'd forget to even clean my own.

James - yeah, these get WAY dirtier than furnace filters, especially if people run them during the summer.  When that happens, I find filters completely covered with moths or mosquitoes... and I mean completely covered.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 10 years ago

Yukky stuff and I am sure most people forget about them as they do the furnance filters.

Posted by Gene Allen, Realty Consultant for Cary Real Estate (Fathom Realty) over 10 years ago

Gene- yes, but multiplied by ten.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 10 years ago

Happy New Year!

Posted by Not a real person over 10 years ago