Filters And Core
This is a twenty-minute job once a year plus a five-minute job every few months, and most homeowners have never been shown either of them.
Short answer
The filters pull out of the unit and are vacuumed or washed and dried. The core slides out and is washed with warm water and mild detergent, rinsed and dried before going back. The exterior hoods are cleared and the condensate drain and trap are checked. None of it needs a technician once somebody has shown you.
The filters
Switch the unit off at the control or unplug it before opening the door.
The filters are flat panels either side of the core, and they pull straight out.
Vacuum them, or wash them in warm water if they are the washable type, and dry them fully before refitting.
Every two to three months during the heating season, which is the interval most manuals specify and almost nobody keeps.
If they are disposable rather than washable, buy a few at a time so the replacement actually happens.
And check the fit, because a filter sitting loose lets air bypass it and the core then loads up.
Why the filters matter to the core
The filters exist to keep the core clean. A neglected filter lets dust through, the core blinds up, the airflow drops and the unit stops ventilating — and cleaning a badly loaded core is much harder than vacuuming a filter. Five minutes every few months prevents the annual job becoming a replacement.
The core
Slides out of the unit, usually on rails, once the filters are out.
Wash it with warm water and a mild detergent — no solvents, no high pressure, nothing abrasive — because the core is a delicate laminated or plastic assembly.
Rinse thoroughly and let it dry completely before refitting.
Once a year, at the start of the heating season, is the usual interval.
Handle it carefully, because a damaged core is an expensive part and it is the whole point of the machine.
And check the manual, because some core types have specific instructions and a few should not be wetted at all.
The rest of the annual check
Exterior intake and exhaust hoods: clear the screens of lint, leaves and insect nests, and check for ice in winter.
The condensate drain and the trap, which if blocked back water into the cabinet.
The grilles in the house, which collect dust like any register.
The fan, listening for bearing noise.
The defrost cycle operation, which is a technician check and is worth having done once.
And the balance, which is also a technician task and which on many installations has never been set.
Common questions
How often should the HRV core be washed?
Once a year, at the start of the heating season.
Can I wash the core myself?
On most units yes, with warm water and mild detergent. Check the manual first.
Why do the filters matter so much?
They keep the core clean. A neglected filter turns an easy annual job into a hard one.