Hi fellow diyers,

The HRV system on my rental just blown up its 3.15A 250V fuse.

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My tenants called last week informing the HRV won't turn on.

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I thought I should diy this instead of asking servicing guys to avoid a huge cost. A year ago, I had a very bad experience with HRV company sending their people with no intent of actually fixing anything, but just selling their new systems. That instance I got it done by myself and wasn't worth time spent on those guys. Now that house is a rental.

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I visited the rental house yesterday and thought I should be able to diy it. Tried a couple of checks with an electrical tester and got to the point where a fuse was blown up. That looked a big win. Had a quick run to local Jaycar and thankfully got the matching fuse, cheap price so I bought 3 of them, just in case.

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Got back into the house attic, replaced the fuse, turned on the system, a small spark blown the new fuse immediately. I had another fuse so I tried again and made sure the fuse is in place very well, turned on the system. It worked just great. Left the place happily leaving an extra fuse to the tenant for any future use.

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40 mins later got a message from tenant. The fuse blown up again. Couldn't go back straightaway, because I live about an hour away, and won't expect the next fuse to just work without anything else fixed.

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Wondering what could be the cause. If it blown up straightaway, it possibly mean the motherboard is damaged, the first fuse in the system worked just too long for about 10+ years. The one I replaced blown up in a blink, the second replaced one worked for 40 minutes.

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Could this be a filter problem? Or motor? bearings? Any guesses? What should I try to keep it diy? Or just give up and call the servicing guys to literally recommend changing the whole system.

HRV mainboard fuse blows